Copper Cycle

The fuzz Cycle Most of the background material for this research research laboratoryoratory go unwrap be cove ruby in greater detail in the berate style later in the semester. Here is some background learning so you depart under wrack the chemistry behind the re processs you seeament per exercise. mevery aspects of our lives entangle chemical mental object substance receptions-?from the batteries that power our cars and cell ph geniuss to the thousands of processes occur hoop within our bodies. Most of these receptions foundation be classified into adept of three main types of chemical replys rushing play offions, panelling- lay down naturalization replys, and oxidation- deduction ( in any case c bothed redo) receptions.Aqueous Solutions(as) Many re action mechanisms occur in an sedimentary purlieu (I. E. , in a event where ions and compounds atomic number 18 throw outd in pissing). When we refer that a reactant or fruit has the physical state (as), w e soexercisingd the substance is disregardd in piddle supply. When an ionic compound is in aqueous ancestor, the several(prenominal) ions argon present in resolving for example, NCAA(as) exists as An+ and CLC- ions travel some in water. solubility Rules Many ionic compounds atomic number 18 disintegrable-?I. E. , they disband in water.Others gener eithery do non dissolve in water and argon considered insoluble. To observe if an ionic compound is soluble-?I. E. , go away dissolve-?in water, we design the solvability Rules Solubility Rules for Ionic Compounds in Water The compound is disintegrable if it has An+, NH 4+ ton (ALWAYS ) 2. CHICHI-, no-, CHIC- 3. CLC-, BRB-, or 1-, object compounds with Gag+, BP+2, and Hag+2 ar insoluble 4. SASS- except compounds with Sagas, cases, scars, Bases, PBS, and Haggis be insoluble The compound is insoluble if it has 5.CHIC-, crack-, IPPP-, except compounds with lie down+, An+, K+, NH+ be soluble 6. SO-, except compounds with Lie+, An+, K+, NH+, ca+2, sir+2, AAA+2 are soluble . hydrated oxide ion, OH-, except compounds The Solubility Rules indicate which compounds are soluble, and thus are correspond as aqueous e. G. , Kill(as), Abaca(as), Noah(as), and so forth The Solubility Rules withal indicate which compounds are insoluble-?I. E. , do not dissolve in water and remain as reals e. G. bass voice+), C exclusively(s), cacao(s), etc.Double Re situationment/Precipitation Reaction For example, consider the reaction mingled with aqueous lead(al) nitrate with aqueous potassium bromide, as shown infra KGB(as) queer genu Note that the chemical compriseulas for the point of intersections geted are floo pluralityd on their charges, to how they emerge on the reactant side of the chemical equation. ICC CHEM. 151 AL The squealer calendar method O ICC, 2013 page 1 of 12 Based on Solubility Rules 4 and 1, we find that BRB is insoluble and KNEE is soluble.Thus, the complete, balanced equation is + 2 KGB(as) Pacific) + 2 KNEE(as) We foundation cornerst starcel the spectator ions from the ionic equation and preserve the profit ionic equation Pub+(as) + 2 BRB -(as) 0 BRB(s) This reaction names a cloudy pastiche with sm only farewellicles of the steadfast suspended in the beginning. When altogether overflowing square(a) has formed, it leave alone begin to settle at the stern of the beaker. Thus, a clear resultant role becoming cloudy when an separate base is added is oftentimes taken as sampleal evidence of a solid or lessen forming.Acids and Bases Acids shadower be defined as substances that disclose hydrated oxide ions (HUH+) when they are change state in water. A hydrated oxide ion is the p roduct of a hydrogen ion that reacts with a water molecule H+(as) + H2O(l) 0 HUH+(as). A hydrated hydrogen ion (H+(as)) is equivalent to an aqueous hydroxide ion. The dickens equations below both represent the unionization of hydrochloric sultry, HCI(as), but the second bingle shows a particular water molecule explicitly. HCI(as) O H+(as) + CLC-(as)HCI(as) + H2O(l) O HUH+(as) + CLC-(as) Acids are usually easy to recognize since their formulas start with H and chase aways coatloid elements other than H-?e. G. HCI(as), HON.(as), and HASPS(as) are all hots. Note that the physical state aqueous, (as), essentialiness be accommodated to distinguish a compound that is acting corresponding an social disease from other forms of a substance. For example, the formula HCI can also be apply for hydrogen chloride gas, HCI(g), so to indicate aqueous hydrochloric panelling, one must bound HCI(as). One useful definition of buttockss is that bums are compounds that recruit hydroxide ions (OH-) when dissolved in water.The dissociation of sodium hydroxide, Noah, is shown below. Noah(s) Noah(as) which is equivalent to An+(as) + OH-(as) Acid-Base Naturalization Reactions In an pane-base naturalization reaction, a hydrogen ion-containing acid re acts with a hydromechanicss base to produce water and a salt (an ionic compound) HCI(as) + Noah(as) O acid base H2O(l) + Niacin(as) water salt Acids can react with bases, regardless of whether the salt is soluble or insoluble. There are other types of acids and bases that can react without forming water.If the reactants and products of an acid/base reaction are colourless and soluble, it is impossible to monitoring device the get ahead of an acid-base reaction based solely on the behavior of the re tooth roots. To help us monitor acid-base reactions, we use litmus study to determine if a solution is acidulent or basic. Litmus authorship changes color depending on the battlefront of H+ or OH- ions in the substance being tested. Blue litmus news report turns red in acidic solutions containing H+ ions, and red litmus piece of music turns good-for-naught in basic solutions containing OH- ions. Age 2 of 12 oxidization/Reduction Reactions In an oxidation/reduction reactio n, electrons are transferralred from one reactant to the other. In the simplest form of these reactions, single-displacement reactions (also called single-replacement reactions), metal ions react with clear metals. If the reaction proceeds, the pure metal gives electrons to the metal action. This make ups the pure metal to become a action and the action to become a pure metal. The action must continuously deport an anion partner which is present either in an ionic solid or in a solution.For example MGM(s) + 2 Gag+(as) 0 2 Gag(s) + MGM+(as) metal action If the charge of an element is changing, that is a sizable feature that an oxidation/ reduction reaction is taking place. Later in the semester you testament learn to the highest degree oxidation numbers which are utilise to spare track of more than complicated oxidation/ reduction reactions. mistreat l interpersonal chemistry The unlike papal bull species obtained in each(prenominal) part is shown in Equation 1 belo w clue(S) fragment I cue+(as) tell II part Ill cue(S) part give out V luscious l.oxidation Copper admixture with Concentrated Nitric Acid, HON.(as) The first tincture involves transforming move metal to horseshit(al) ions, clue+, utilize concentrated azotic acid, HON.(as). At the homogeneous time, the nitrate ions (NON-) undergo a series of reactions to form northward monoxide, NO. This product rapidly reacts with oxygen in the air to form NON, a brown gas. The presence of propel+(as) makes the solution low. When the reaction mixture is weaken with water, the pool stick+ ions are hydrated (surrounded by water) to form the octahedral decomposable ion, inform(H2O)62+, as shown below.Six water molecules (shown as red O and white H atoms) are bonded to a incite+ ion (shown in gray as the interchange atom). cue+(as) + 6 H2O(l) 0 clue(H2O)62+(as) Figure 1 page 3 of 12 gait II Chemistry II. Precipitating cue stick(OH)2(s) with Noah(as) In expose II, two reactions a re carried out by adding Noah(as). In the first reaction, the hydroxide ions (OH-) from the Noah(as) alter the spare hydroxide ions (HUH+) feet over from the previous part HUH+(as) + OH-(as) 2 H2O(l) at one time all the HUH+ ions are pine awayd, additional OH- ions react with the instigate+ ion to form cue stick(OH)2 fall down. erstwhile all the cue stick+ ions give way reacted, no more precipitate forms. summarizeing more OH- ions makes the solution basic, so it can turn red litmus piece of music bad. Figure 2 on the next page shows the step-wise reaction of discriminative stimulus+ with Noah. Figure 2 tonicity-wise lesson of the Precipitation of instigate(OH)2 in go against II Remember inspire(H2O)2+ indicates the same substance as clew+. initiatory Beaker At the end of portion I, hydrated pig complex, prompt+ are present, devising he solution blue, and excess hydroxide ions (HUH+) remain from the azotic acid use. 2nd Beaker Adding Noah(as) to the blue soluti on results in the OH- ions neutralizing the HUH+ ions to form water HUH+(as) + OH-(as) 0 2 H2O(l).The An+ ions and resulting water molecules are not shown. triplet and quaternate Beakers at one time all the HUH+ are neutralized, adding more Noah(as) results in the OH- ions reacting with the Cue+ to form the blue Cue(OH)2(s) precipitate shown at the bottom of the beaker. Water molecules released from the complex ion are not shown. 5th Beaker When all of the Cue+ ions have been altered to Cue(OH)2(s) precipitate, adding more Noah(as) results in unrelated OH- ions in solution, which makes the solution basic. Red litmus paper can be used to verify the solution is basic.Note that the solution is no bimestrial blue since no Cue+ ions are present in the solution. flavor Ill Chemistry Ill. Converting solid Cue(OH)2 to solid Cue In Part Ill of the succession, the reaction mixture is change. This transforms the Cue(OH)2 precipitate to Cue precipitate. page 4 of 12 The Cue precipitat e is separated from the solution, called the supernatant facile, using a method called gravitational force filtration. The mixture is diffuseed using a deform funnel shape, ND the solid is realiseed on strive paper. The supernatant liquid runs finished the filter paper and collects in a beaker.This resulting filtered solution is called the strive. stair IV Chemistry V. Dissolving Cue(s) with sulfuric acid, HASPS(as) In Part V, the Cue precipitate is dissolved using sulfuric acid, HASPS(as). This redo reaction returns papal bull to its aqueous phase. Step V Chemistry V. Reducing Cue+ ions with atomic number 30 Metal In Part V, zinc metal ( panelling) is added to the copper solution to convert the copper ions back to copper metal, Cue(s). The resulting solution will contain colorless zinc ions, Zen+(as) and copper solid. Visible evidence of this reaction is spy as bubbles of gas being released from the solution. Since the HUH+ ions do not dissolve the Cue metal, the amount of copper yielded is not affected by excess acid. ) name the gas displaced from the acid in this reaction. When the solution becomes colorless, all of the Cue+ ions have been converted to Cue metal. All of the excess Zen metal is also converted to Zen+ ion by the excess HUH+ ions from the sulfuric acid, HASPS(sub out-of-pocketd to dissolve the Cue precipitate in Part IV. at a time all the Zen metal is dissolved, the Cue metal can be isolated by decanting, or pouring off, the supernatant liquid. The Cue will accordingly be rinsed, dried, and weighed as described in the summons. Age 5 of 12 In this experimentation, you will carry out a series of reactions starting with copper metal. This will give you practice handling chemical reagents and reservation observations. It is normal for scientists to observe materials before they react, what happens during a reaction and how it looks when the reaction has come to completion. The product of the final reaction will be copper metal and the part copper that is retrieve will be calculated. **Lab Notebook** You should accept one table that contains the circle of copper at the beginning and ND of the experiment on with % of copper recovered.This table should embroil Mass of copper at the start of experiment (in Part l) Mass of copper + evaporating distribute (from Part V) Mass of empty evaporating dish (from Part V) Mass of copper recovered (from Part V) Percent of copper recovered Record observations for each of the locomote (I-V) of the copper cycle in your lab book. Be reliable to denominate each step (I-V). The observations for each step should include the appearance of the reactants before the reaction the appearance of the reactants during the reaction (for example, bubbles, flames, etc. The appearance of the products after(prenominal) the reaction.Your observations should include state(s) of matter, color, texture, smell, etc. Where applicable. If your observations are not detailed, you whitetho rn not welcome rich credit. One step also requires a specific chemical test using litmus paper to check for acidity. Be certainly to also record the results of these tests in your lab notebook. **You will turn in work planing machine pages 11-12 along with the duplicate pages from your lab notebook. Step l Procedure Oxidation Cue with concentrated nitric acid, HON.(as) 1 . Place a judge of deliberation paper in the balance. Tare the balance, so it reads 0. 0000 g. apply forceps to transfer to the highest degree 0. 5-0. 40 g of Cue strips onto the weighing paper. Record the mass of the Cue strips. extendancing the Cue strips into a clean 250-ml beaker labeled with one of your aggroup members initials. Record the appearance of the copper metal in your lab typography. watchfulness Concentrated nitric acid is highly corrosive, so it can cause severe chemical burn and damage clothing. Handle with manage and subjugate breathing the fumes. any(prenominal) nitric acid spille d on shinny must be rinsed immediately with water for 15 minutes. Any acid spilled on your work area must be neutralized thus the inbuilt rear should be stifleed and dried. guardianship Concentrated nitric acid reacts with copper metal to form brown virulent NON gas. Leave the reaction beaker in the fume oaf until all of the brown gas is show in the hood. ICC CHEM. 151 AL The Copper Cycle page 6 of 12 2. In a fume hood, use a 10-ml graduated piston chamber to guardedly posting about 3 ml of concentrated nitric acid, HON.(as). easily pour the nitric acid onto the Cue strips in the beaker, swirling the beaker to increase take among the Cue and nitric acid until all of the solid Cue has dissolved and the NON gas has escaped.Keep the action beaker in the hood until all the toxic brown NON gas is gone, and keep your face away from the hood to countermand inhaling nitric acid fumes and NON gas. cite the reaction between HON. and the Cue metal in your lab makeup. 3. Dilute the resulting solution with about 10 ml of habitant water. define the appearance of the resulting solution containing Cue+ in your data table. Step II Chemistry Precipitating Cue(OH)2(s) with Noah(as) go away over from the previous part. Once all the HUH+ ions are neutralized, additional OH- ions react with the Cue+ complex ion to form a gelatinous blue Cue(OH)2 precipitate.Once all the Cue+ ions have reacted, no more precipitate forms. Adding more OH- ions makes the solution basic, so it can turn red litmus paper blue. The shot sequence on the next page outlines the step-by-step process that occurs during this step. Step II Procedure Precipitating Cue(OH)2 with Noah solution CAUTION Sodium hydroxide (Noah) can easily damage eyes. It is corrosive and can cause chemical burns and damage clothing. Any Noah splashed into eyes or spilled on uncase must be rinsed immediately with water for 15 minutes. Any base spilled on your work area must be neutralized then the entire area shou ld be washed and dried. While invariably aspiration the Cue solution, slowly add MM Noah(as) from the shake offper bottles. First, the OH- from the Noah added will neutralize the excess acid left over from Part l. 2. Once all the acid is neutralized, additional OH- ions react with the Cue+ to form Cue(OH)2(s), a blue precipitate. Record what you observe in your lab report. When adding more Noah does not produce more precipitate, the solution can be tested to determine if all the Cue+ has been precipitated and additional OH- has made the solution basic. using up red litmus paper to test if the solution is basic as follows.Without stubbing any precipitate, use a glass stir rod to place a drop of solution (NOT the precipitate) on a piece of red litmus paper. If it turns blue, the solution is basic. S give-up the ghost adding Noah when the solution turns red litmus paper blue. Describe your litmus test in your lab report. Page 7 of 12 Step-wise Illustration of the Precipitation of p art II 1st Beaker Check solution using red litmus paper (refer to background handout). Continue adding base until solution is basic. At the end of Part I Cue+ ions are present, making the solution blue, and excess hydroxide ions (HUH+) remain from the nitric acid used. D Beaker Adding Noah(as) to the blue solution results in the OH- ions ions are not shown. 3rd and quaternate Beakers 5th Beaker Once all the HUH+ are neutralized, adding more Noah(as) results in the OH- ions reacting with the Cue+ to form the blue Cue(OH)2(s) precipitate shown at the bottom of the beaker. When all of the Cue+ ions have been converted to Cue(OH)2(s) precipitate, adding more Noah(as) results in unrelated OH- ions in solution, which makes the solution basic. Red litmus paper can be used to confirm the solution is basic. Note that the solution is no longer blue since no Cue+ ions are present in the solution.In reality, your solution may legato appear blue because of the dispersion of the Cue(OH)2 in the solution by mixing. Step Ill Procedure Converting Cue(OH)2(s) to Cue(s) 1. Set up a ring stand as shown in the figure at the right. Set up a ring fasten, and put a wire gauze on clear up of it. Above it, adjoin another ring clamp with a diam large enough to go around a 250-ml beaker. You are loss to set your 250 ml beaker on the sink ring and gauze. The top(prenominal) clamp will hold the beaker in place so it does not fall. 2. Add about 30-40 ml of denizen water to your reaction beaker from Part II.Carefully place the beaker on the ring stand inwardly the upper ring. CAUTION light heat the beaker over a medium flame. (Set the inner cone of the bunsen burner burner flame to a height of about 1. 5 in and the lower ring stand about 4 inches above the top of the bunsen burner burner). Constantly stir the solution with the glass end of the divine guidance rod until all the blue precipitate turns black, and the solution is clear. If the solution starts to nose candy or boi l, immediately remove the beaker from the heat and let the solution placid slightly. Describe what happens to the Cue(OH)2 precipitate upon heating in your lab port. Age 8 of 12 3. Allow the beaker and contents to cool. While they are cooling, set up the gravity filtration apparatus. Obtain a second ring stand, and attach a ring clamp that is small enough to hold the p soundic funnel. dress the filter paper as shown below Finally, place the plastic funnel in the small ring clamp, and place a 400-ml beaker beneath it to collect the filtrate (the liquid that goes through and through the filter paper). The funnels stem should be skillful inside the beaker to prevent splashing. 4. Use the markings on a clean 150-ml beaker to measure out about 25 ml of denizen water.Boil the water on a hotplate to wash the precipitate in step 6. 5. When the 250-ml reaction beaker has cooled to get on temperature, pour the Cue precipitate into the funnel to filter the contents. Transfer the last trace s of the solid from the reaction beaker into the funnel, using a stream of denizen water. 6. Use a disposable pipette to wash the precipitate on the filter paper using the hot denizen water heated in the 150-ml beaker. Allow each portion of hot water to feed through the filter paper into the beaker below before adding the next portion. Use 15 ml of the hot denizen water to thoroughly wash the Cue precipitate.Copper CycleCH 130 B General Chemistry I The Lab Report As a scientist you are obligated for conveying the results of an experiment to a supervisor, a colleague, or the public. Often, you will convey this information in the form of a scientific paper describing your work. This paper needs to clearly describe wherefore and how an experiment was done, and it must include an interpretation of results, including a discussion of their importance and any significant sources of demerit. You lab report will be a brief version of a publication.It should contain the following sections Introduction This part of the paper should be an rendering of the purpose of the experiments and a review of relevant principles related to the work. This is NOT a procedure. Data and Calculations Attach your graded summary sheet from the experiment. If you did any calculations incorrectly, attach a sheet with correct calculations. In addition to the summary sheet include a table which details observations and known information. What did the solutions look like, what were their concentrations, etc.?Results and Discussion This part of the report should include an in-depth discussion of your data and observations, in essay form. Again, do not rewrite a detailed procedure here, but summarize what you did in the experiment. Describe what you observed. What do your results tell you? justify whether your results matched your expected results. If they didnt (and they surely didnt match exactly) discuss the reasons why this might be the case. What are the possible sources of error?How wo uld each of these sources of error affect the result? Convince yourself and your reader that you are correct in your conclusions. Reiterate your data in relation to your conclusions. You should be able to inform the chemistry that is occurring in the experiment. Please remember the basic principles of writing. Your lab report must be mechanically correct (grammar and punctuation). It is your responsibility to check your grammar and spelling. You will be graded on this. How is a lab report different than an English paper? Lab reports are written in third person, passive, past tense. The rough draft and final draft can be double-sided, but they must be double-spaced. Lab reports use simple, declarative sentences that connect observations to conclusions. The simplest way to say something is often the best. There is no page or word requirement. Say what you have to say so that your reader understands. rough-cut mistakes to avoid Try not to start your introduction with the purpose of this experiment or a similar phrase. Compounds/elements are not proper nouns. Do not capitalize them. Use superscripts and subscripts. Proofread This lab report should be approximately 2 pages long. You will all write the lab report for the same experiment. The experiment is labeled on your schedule as Cu Cycle. A completed rough draft of your lab report is due on (or before) October 22. The rough draft will be counted as one-half of the total grade for the paper. The final draft of your report will be due on November 26 in class.Copper CycleThe Copper Cycle Most of the background material for this laboratory will be covered in greater detail in the lecture course later in the semester. Here is some background information so you will understand the chemistry behind the reactions you will perform. Many aspects of our lives involve chemical reactions-?from the batteries that power our cars and cell phones to the thousands of processes occurring within our bodies. Most of these r eactions can be classified into one of three main types of chemical reactions precipitation reactions, acid-base naturalization reactions, and oxidation- deduction (also called redo) reactions.Aqueous Solutions(as) Many reactions occur in an aqueous environment (I. E. , in a solution where ions and compounds are dissolved in water). When we indicate that a reactant or product has the physical state (as), we mean the substance is dissolved in water. When an ionic compound is in aqueous solution, the individual ions are present in solution for example, NCAA(as) exists as An+ and CLC- ions moving around in water. Solubility Rules Many ionic compounds are soluble-?I. E. , they dissolve in water.Others generally do not dissolve in water and are considered insoluble. To determine if an ionic compound is soluble-?I. E. , will dissolve-?in water, we use the Solubility Rules Solubility Rules for Ionic Compounds in Water The compound is SOLUBLE if it has An+, NH 4+ ton (ALWAYS ) 2. CHICHI-, N ON-, CHIC- 3. CLC-, BRB-, or 1-, except compounds with Gag+, BP+2, and Hag+2 are insoluble 4. SASS- except compounds with Sagas, cases, scars, Bases, PBS, and Haggis are insoluble The compound is INSOLUBLE if it has 5.CHIC-, crack-, IPPP-, except compounds with Lie+, An+, K+, NH+ are soluble 6. SO-, except compounds with Lie+, An+, K+, NH+, ca+2, sir+2, AAA+2 are soluble . Hydroxide ion, OH-, except compounds The Solubility Rules indicate which compounds are soluble, and thus are represented as aqueous e. G. , Kill(as), Abaca(as), Noah(as), etc. The Solubility Rules also indicate which compounds are insoluble-?I. E. , do not dissolve in water and remain as solids e. G. Basso+), Call(s), cacao(s), etc.Double Replacement/Precipitation Reaction For example, consider the reaction between aqueous lead(al) nitrate with aqueous potassium bromide, as shown below KGB(as) Puff KNEE Note that the chemical formulas for the products formed are based on their charges, to how they appear on the re actant side of the chemical equation. ICC CHEM. 151 AL The copper cycle O ICC, 2013 page 1 of 12 Based on Solubility Rules 4 and 1, we find that BRB is insoluble and KNEE is soluble.Thus, the complete, balanced equation is + 2 KGB(as) Pacific) + 2 KNEE(as) We can cancel the spectator ions from the ionic equation and write the net ionic equation Pub+(as) + 2 BRB -(as) 0 BRB(s) This reaction produces a cloudy mixture with small particles of the solid suspended in the solution. When enough solid has formed, it will begin to settle at the bottom of the beaker. Thus, a clear solution becoming cloudy when another solution is added is often taken as experimental evidence of a solid or precipitate forming.Acids and Bases Acids can be defined as substances that produce hydroxide ions (HUH+) when they are dissolved in water. A hydroxide ion is the product of a hydrogen ion that reacts with a water molecule H+(as) + H2O(l) 0 HUH+(as). A hydrated hydrogen ion (H+(as)) is equivalent to an aqueou s hydroxide ion. The two equations below both represent the unionization of hydrochloric acid, HCI(as), but the second one shows a particular water molecule explicitly. HCI(as) O H+(as) + CLC-(as)HCI(as) + H2O(l) O HUH+(as) + CLC-(as) Acids are usually easy to recognize since their formulas start with H and contains nonmetal elements other than H-?e. G. HCI(as), HON.(as), and HASPS(as) are all acids. Note that the physical state aqueous, (as), must be included to distinguish a compound that is acting like an acid from other forms of a substance. For example, the formula HCI can also be used for hydrogen chloride gas, HCI(g), so to indicate aqueous hydrochloric acid, one must specify HCI(as). One useful definition of bases is that bases are compounds that produce hydroxide ions (OH-) when dissolved in water.The dissociation of sodium hydroxide, Noah, is shown below. Noah(s) Noah(as) which is equivalent to An+(as) + OH-(as) Acid-Base Naturalization Reactions In an acid-base naturaliz ation reaction, a hydrogen ion-containing acid reacts with a hydromechanicss base to produce water and a salt (an ionic compound) HCI(as) + Noah(as) O acid base H2O(l) + Niacin(as) water salt Acids can react with bases, regardless of whether the salt is soluble or insoluble. There are other types of acids and bases that can react without forming water.If the reactants and products of an acid/base reaction are colorless and soluble, it is impossible to monitor the progress of an acid-base reaction based solely on the appearance of the solutions. To help us monitor acid-base reactions, we use litmus paper to determine if a solution is acidic or basic. Litmus paper changes color depending on the presence of H+ or OH- ions in the substance being tested. Blue litmus paper turns red in acidic solutions containing H+ ions, and red litmus paper turns blue in basic solutions containing OH- ions. Age 2 of 12 Oxidation/Reduction Reactions In an oxidation/reduction reaction, electrons are trans ferred from one reactant to the other. In the simplest form of these reactions, single-displacement reactions (also called single-replacement reactions), metal ions react with pure metals. If the reaction proceeds, the pure metal gives electrons to the metal action. This causes the pure metal to become a action and the action to become a pure metal. The action must always have an anion partner which is present either in an ionic solid or in a solution.For example MGM(s) + 2 Gag+(as) 0 2 Gag(s) + MGM+(as) metal action If the charge of an element is changing, that is a good indication that an oxidation/ reduction reaction is taking place. Later in the semester you will learn about oxidation numbers which are used to keep track of more complicated oxidation/ reduction reactions. Step l Chemistry The different copper species obtained in each part is shown in Equation 1 below cue(S) Part I cue+(as) Part II part Ill cue(S) part Part V blue l.Oxidation Copper Metal with Concentrated Nitric Acid, HON.(as) The first step involves transforming Cue metal to copper(al) ions, Cue+, using concentrated nitric acid, HON.(as). At the same time, the nitrate ions (NON-) undergo a series of reactions to form nitrogen monoxide, NO. This product rapidly reacts with oxygen in the air to form NON, a brown gas. The presence of Cue+(as) makes the solution blue. When the reaction mixture is diluted with water, the Cue+ ions are hydrated (surrounded by water) to form the octahedral complex ion, Cue(H2O)62+, as shown below.Six water molecules (shown as red O and white H atoms) are bonded to a Cue+ ion (shown in gray as the central atom). Cue+(as) + 6 H2O(l) 0 Cue(H2O)62+(as) Figure 1 page 3 of 12 Step II Chemistry II. Precipitating Cue(OH)2(s) with Noah(as) In Part II, two reactions are carried out by adding Noah(as). In the first reaction, the hydroxide ions (OH-) from the Noah(as) neutralize the excess hydroxide ions (HUH+) feet over from the previous part HUH+(as) + OH-(as) 2 H2O(l) On ce all the HUH+ ions are neutralized, additional OH- ions react with the Cue+ ion to form Cue(OH)2 precipitate. Once all the Cue+ ions have reacted, no more precipitate forms.Adding more OH- ions makes the solution basic, so it can turn red litmus paper blue. Figure 2 on the next page shows the step-wise reaction of Cue+ with Noah. Figure 2 Step-wise Illustration of the Precipitation of Cue(OH)2 in Part II Remember Cue(H2O)2+ indicates the same substance as Cue+. 1st Beaker At the end of Part I, hydrated copper complex, Cue+ are present, making he solution blue, and excess hydroxide ions (HUH+) remain from the nitric acid used. 2nd Beaker Adding Noah(as) to the blue solution results in the OH- ions neutralizing the HUH+ ions to form water HUH+(as) + OH-(as) 0 2 H2O(l).The An+ ions and resulting water molecules are not shown. 3rd and 4th Beakers Once all the HUH+ are neutralized, adding more Noah(as) results in the OH- ions reacting with the Cue+ to form the blue Cue(OH)2(s) precipi tate shown at the bottom of the beaker. Water molecules released from the complex ion are not shown. 5th Beaker When all of the Cue+ ions have been converted to Cue(OH)2(s) precipitate, adding more Noah(as) results in unrelated OH- ions in solution, which makes the solution basic. Red litmus paper can be used to confirm the solution is basic.Note that the solution is no longer blue since no Cue+ ions are present in the solution. Step Ill Chemistry Ill. Converting solid Cue(OH)2 to solid Cue In Part Ill of the sequence, the reaction mixture is heated. This transforms the Cue(OH)2 precipitate to Cue precipitate. Page 4 of 12 The Cue precipitate is separated from the solution, called the supernatant liquid, using a method called gravity filtration. The mixture is filtered using a filter funnel, ND the solid is collected on filter paper. The supernatant liquid runs through the filter paper and collects in a beaker.This resulting filtered solution is called the filtrate. Step IV Chemistr y V. Dissolving Cue(s) with sulfuric acid, HASPS(as) In Part V, the Cue precipitate is dissolved using sulfuric acid, HASPS(as). This redo reaction returns copper to its aqueous phase. Step V Chemistry V. Reducing Cue+ ions with Zinc Metal In Part V, zinc metal (Zen) is added to the copper solution to convert the copper ions back to copper metal, Cue(s). The resulting solution will contain colorless zinc ions, Zen+(as) and copper solid. Visible evidence of this reaction is observed as bubbles of gas being released from the solution. Since the HUH+ ions do not dissolve the Cue metal, the amount of copper yielded is not affected by excess acid. ) Identify the gas displaced from the acid in this reaction. When the solution becomes colorless, all of the Cue+ ions have been converted to Cue metal. All of the excess Zen metal is also converted to Zen+ ion by the excess HUH+ ions from the sulfuric acid, HASPS(subdued to dissolve the Cue precipitate in Part IV. Once all the Zen metal is dis solved, the Cue metal can be isolated by decanting, or pouring off, the supernatant liquid. The Cue will then be rinsed, dried, and weighed as described in the procedure. Age 5 of 12 In this experiment, you will carry out a series of reactions starting with copper metal. This will give you practice handling chemical reagents and making observations. It is typical for scientists to observe materials before they react, what happens during a reaction and how it looks when the reaction has come to completion. The product of the final reaction will be copper metal and the percent copper that is recovered will be calculated. **Lab Notebook** You should include one table that contains the mass of copper at the beginning and ND of the experiment along with % of copper recovered.This table should include Mass of copper at the start of experiment (in Part l) Mass of copper + evaporating dish (from Part V) Mass of empty evaporating dish (from Part V) Mass of copper recovered (from Part V) Perc ent of copper recovered Record observations for each of the steps (I-V) of the copper cycle in your lab book. Be sure to label each step (I-V). The observations for each step should include the appearance of the reactants before the reaction the appearance of the reactants during the reaction (for example, bubbles, flames, etc. The appearance of the products after the reaction.Your observations should include state(s) of matter, color, texture, smell, etc. Where applicable. If your observations are not detailed, you may not receive full credit. One step also requires a specific chemical test using litmus paper to check for acidity. Be sure to also record the results of these tests in your lab notebook. **You will turn in worksheet pages 11-12 along with the duplicate pages from your lab notebook. Step l Procedure Oxidation Cue with concentrated nitric acid, HON.(as) 1 . Place a sample of weighing paper in the balance. Tare the balance, so it reads 0. 0000 g. Use forceps to transfer about 0. 5-0. 40 g of Cue strips onto the weighing paper. Record the mass of the Cue strips. Transfer the Cue strips into a clean 250-ml beaker labeled with one of your group members initials. Record the appearance of the copper metal in your lab report. CAUTION Concentrated nitric acid is highly corrosive, so it can cause severe chemical burns and damage clothing. Handle with care and avoid breathing the fumes. Any nitric acid spilled on skin must be rinsed immediately with water for 15 minutes. Any acid spilled on your work area must be neutralized then the entire rear should be washed and dried.CAUTION Concentrated nitric acid reacts with copper metal to form brown toxic NON gas. Leave the reaction beaker in the fume hood until all of the brown gas is vented in the hood. ICC CHEM. 151 AL The Copper Cycle page 6 of 12 2. In a fume hood, use a 10-ml graduated cylinder to carefully measure about 3 ml of concentrated nitric acid, HON.(as). Slowly pour the nitric acid onto the Cue st rips in the beaker, swirling the beaker to maximize contact between the Cue and nitric acid until all of the solid Cue has dissolved and the NON gas has escaped.Keep the action beaker in the hood until all the toxic brown NON gas is gone, and keep your face away from the hood to avoid inhaling nitric acid fumes and NON gas. Describe the reaction between HON. and the Cue metal in your lab report. 3. Dilute the resulting solution with about 10 ml of denizen water. Describe the appearance of the resulting solution containing Cue+ in your data table. Step II Chemistry Precipitating Cue(OH)2(s) with Noah(as) left over from the previous part. Once all the HUH+ ions are neutralized, additional OH- ions react with the Cue+ complex ion to form a gelatinous blue Cue(OH)2 precipitate.Once all the Cue+ ions have reacted, no more precipitate forms. Adding more OH- ions makes the solution basic, so it can turn red litmus paper blue. The picture sequence on the next page outlines the step-by-step process that occurs during this step. Step II Procedure Precipitating Cue(OH)2 with Noah solution CAUTION Sodium hydroxide (Noah) can easily damage eyes. It is corrosive and can cause chemical burns and damage clothing. Any Noah splashed into eyes or spilled on skin must be rinsed immediately with water for 15 minutes. Any base spilled on your work area must be neutralized then the entire area should be washed and dried. While constantly stirring the Cue solution, slowly add MM Noah(as) from the dropper bottles. First, the OH- from the Noah added will neutralize the excess acid left over from Part l. 2. Once all the acid is neutralized, additional OH- ions react with the Cue+ to form Cue(OH)2(s), a blue precipitate. Record what you observe in your lab report. When adding more Noah does not produce more precipitate, the solution can be tested to determine if all the Cue+ has been precipitated and additional OH- has made the solution basic. Use red litmus paper to test if the soluti on is basic as follows.Without stubbing any precipitate, use a glass stir rod to place a drop of solution (NOT the precipitate) on a piece of red litmus paper. If it turns blue, the solution is basic. Stop adding Noah when the solution turns red litmus paper blue. Describe your litmus test in your lab report. Page 7 of 12 Step-wise Illustration of the Precipitation of part II 1st Beaker Check solution using red litmus paper (refer to background handout). Continue adding base until solution is basic. At the end of Part I Cue+ ions are present, making the solution blue, and excess hydroxide ions (HUH+) remain from the nitric acid used. D Beaker Adding Noah(as) to the blue solution results in the OH- ions ions are not shown. 3rd and 4th Beakers 5th Beaker Once all the HUH+ are neutralized, adding more Noah(as) results in the OH- ions reacting with the Cue+ to form the blue Cue(OH)2(s) precipitate shown at the bottom of the beaker. When all of the Cue+ ions have been converted to Cue(OH )2(s) precipitate, adding more Noah(as) results in unrelated OH- ions in solution, which makes the solution basic. Red litmus paper can be used to confirm the solution is basic. Note that the solution is no longer blue since no Cue+ ions are present in the solution.In reality, your solution may still appear blue because of the dispersion of the Cue(OH)2 in the solution by mixing. Step Ill Procedure Converting Cue(OH)2(s) to Cue(s) 1. Set up a ring stand as shown in the figure at the right. Set up a ring clamp, and put a wire gauze on top of it. Above it, attach another ring clamp with a diameter large enough to go around a 250-ml beaker. You are going to set your 250 ml beaker on the lower ring and gauze. The upper clamp will hold the beaker in place so it does not fall. 2. Add about 30-40 ml of denizen water to your reaction beaker from Part II.Carefully place the beaker on the ring stand inside the upper ring. CAUTION Gently heat the beaker over a medium flame. (Set the inner con e of the Bunsen burner flame to a height of about 1. 5 inch and the lower ring stand about 4 inches above the top of the Bunsen burner). Constantly stir the solution with the glass end of the stirring rod until all the blue precipitate turns black, and the solution is clear. If the solution starts to bump or boil, immediately remove the beaker from the heat and let the solution cool slightly. Describe what happens to the Cue(OH)2 precipitate upon heating in your lab port. Age 8 of 12 3. Allow the beaker and contents to cool. While they are cooling, set up the gravity filtration apparatus. Obtain a second ring stand, and attach a ring clamp that is small enough to hold the plastic funnel. Prepare the filter paper as shown below Finally, place the plastic funnel in the small ring clamp, and place a 400-ml beaker beneath it to collect the filtrate (the liquid that goes through the filter paper). The funnels stem should be Just inside the beaker to prevent splashing. 4. Use the markings on a clean 150-ml beaker to measure out about 25 ml of denizen water.Boil the water on a hotplate to wash the precipitate in step 6. 5. When the 250-ml reaction beaker has cooled to room temperature, pour the Cue precipitate into the funnel to filter the contents. Transfer the last traces of the solid from the reaction beaker into the funnel, using a stream of denizen water. 6. Use a disposable pipette to wash the precipitate on the filter paper using the hot denizen water heated in the 150-ml beaker. Allow each portion of hot water to drain through the filter paper into the beaker below before adding the next portion. Use 15 ml of the hot denizen water to thoroughly wash the Cue precipitate.