Conversion of Mass pdf - Conservation of mass lab report for Chemistry lab PDF

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Conservation of mass lab report for Chemistry lab...

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Conservation of Mass Report! Introduction: "

The purpose of this experiment is to find the mass of copper after a series of chemical

reaction. The start and final chemical would still be Copper. The series includes combustion, decomposition, single and double replacement reactions. Through each reactions, we can observe the changes taken place.! Chemical responsible: Gloves, googles and lab coat are typical safety protection item need in a chemical lab. Nitric acid and Copper (II) sulphate are both toxic, corrosive and an oxidant that can cause severe skin burns and turn skin yellow on contact. While, Sodium hydroxide and sulphuric acid are both toxic and corrosive that can cause severe skin damage and eye data. Copper (II) is a toxic and an irritant and zinc sulphate is an irritant that could also be toxic. Furthermore, the byproduct of Zinc metal and sulphuric acid, Hydrogen gas, is highly flammable. Thus this reaction should be perform in the hood to minimise any chances of fire or explosion.! Procedure: 1. Conversion of Copper Metal to Copper (II) Nitrate Weight around 0.250 to 0.350g of copper metal in a 150ml beaker and add 15ml of 6M of nitric acid to the same copper and wait until it complete reacts (if not, gently heat it).! 2. Conversion of Copper (II) Nitrate to Copper (II) Hydroxide Wait until the beaker to cool to room temperature and add 25ml of distilled water into the beaker. Pour 10ml of 6M NaOH into the same solution beaker and test until the pH paper test blue (alkaline). The pale blue precipitate, which is now present in your beaker is copper (II) hydroxide)! 3. Conversion to Copper (II) Hydroxide to Copper (II) Oxide Add 50ml of distilled water to your pale blue copper (II) hydroxide solution and boil the solution. Gently stirring until the pale blue precipitate is convert to black precipitate: copper (II) oxide.! 4. Conversion of Copper (II) Oxide to Copper (II) Sulphate

Allow the solution to cool and the precipitate to settle at the bottom. After use gravity filtration to collect the filtrate in a 600ml beaker to be used for waste. Replace the waster beaker with beaker originally contained copper (II) oxide and pour the 15ml of 3M of sulphuric acid into the brown solid on the filter paper and gentle stir the gravity funnel. Repeat this process until no solid remain in the solution and finish the process by rinsing the empty beaker and transfer the blue solution over.! 5. Conversion of Copper (II) Sulphate to Copper metal Bring your beaker back to the hood and slowly add the 1g of zinc metal to the copper (II) sulphate solution. The gas will bubble out and allow the solution to turn clear blue colour.! 6. Destruction of excess Zinc Add about 15ml of 3M sulphuric acid to your copper zinc solution mixture, and make sure there is a small opening so that the excess gas can escape and wait until next lab.! 7. Washing the Copper metal Allow the metallic copper to settle to the bottom of your beaker undisturbed and pour as much of the liquid into the waster beaker as possible. Add 10ml of distilled water to the copper metal solution and transfer it to the weighted evaporating dish. Do this process with the evaporation dish two more times. ! 8. Recovering the Copper metal Obtain a 25ml beaker, fill it with water halfway and prepare to heat it up. Place the evaporating dish on top of the beaker and heat until the copper metal is dry (occasionally remove the evaporating dish from the top of the beaker and tap the side gently. When the copper metal move freely, then the copper metal is fully dry. And weigh the copper to determine the recovered mass.! Report/ Observation:

1. Cu +HNO₃ ! Cu (NO₃) + H • What is in the solution after the reaction is complete? Copper nitrate! • Observations: Copper slowly broke down into pieces, change to clear blue! 2. Cu (NO₃)2 + NaOH ! Cu(OH)2 + 2Na (NO)3 Reaction Type: Double Replacement! HNO3 + NaOH ! Na(NO3) + H2O! • Reaction Type: Double Replacement! • What is formed in the solution besides Cu(OH)2 ? Na(NO3)! • Observations: Air bubbles formation, milky to green to milky blue after adding more NaOH solution! 3. Cu(OH)2 ! CuO +H2O (! represent heat) • Reaction type: Decomposition! • What is removed by the washing and decantation process at the end of step 12? Na(NO3) was removed.! • Observation: Solution turn from blue to dark green to black when heat, after cool black precipitate at the bottom! 4. CuO +H2SO4 ! CuSO4 + H2O • Reaction type: double replacement! • What is in the solution at the end of this step? CuSO4! • Observation: The solution turned a light blue colour!

5. Zn + CuSO4 ! Cu + ZnSO4 • Reaction type: Single replacement ! Zn +H2SO4 ! H2 +ZnSO4! • Reaction type: Single replacement! • What happens when the zinc is added? Copper metal starts to appear! • What is removed by the washing and decantation at the end of this part of your experiment? The left-over zinc was removed by the washing and decantation! • Observations: air bubbles formation, fizzing, copper separate from the solution.! Discussion: The initiation mass of copper metal was 0.351 grams. After the series of chemical reaction, the weight of the copper metal recovered was measured to be 0.340 grams. This then can be determines the percentage covered copper metal to be the amount recovered over the original mass of copper. The percentage of covered turns out to be 96.86%. However there could be a slight error in the percent of recovered copper since measurement error or the salt are not fully react. ! Sample calculation: Weight of copper metal = weight of copper metal and evaporating dish - weight of clean evaporating dish = 107.750- 107.390 = 0.340! Percent of copper recovered = mass of recovered copper / mass of initial copper x 100 = 0.340/0.351 x 100 = 96.86%! Post lab questions: 1. A student performed this experiment but was not particularly careful in the following the procedure. Explain how each of the following procedural changes would affect his/her mass of copper metal recovered (too high, too low, or not changed)! a. Not enough sodium hydroxide was added, so the solution was still acidic when the beaker was heated to convert the copper (II) hydroxide to copper(II) oxide.

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Less copper will be able to convert to Cu2+ thus change the amount of Copper

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recovered due to the fact the Copper metal would stay solid! b. There was still some brown copper oxide present on the filter paper when the student moved on to the next step (adding zinc metal) "

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Less copper will be able to recovered since the acidic Copper would not be able

to convert to Cu(OH)2 c. The copper metal was heated too long. "

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The copper would combine would oxygen and form oxygen oxide when it is

over-heated. Because copper is heavier than oxygen, the mass of recovered of copper is lowered.

Conclusions: The mass recovered is 0.340 and the mass we started with is 0.351 grams of copper metal. Thus, this value are used to determine that the percent recovered is 98.68%! Acknowledgement:...