The idea of the experiment is to determine which equation is correct. There are 2 equations of CuCo3 and I have to find out which gases are given off when CuCo3 is given off.

Copper (I) oxide Cu2O

Copper (I) oxide is obtained by reducing an alkaline solution of copper (II) salts. It’s colour is a red precipitate. This reaction is the one used to identify reducing sugars in the Fehling’s and Benedict’s tests.

Copper (I) oxide reacts with dilute tetraoxosulphate (VI) acid to form copper (II) tetraoxosulphate (VI) and copper. In this reaction, copper is reduced and oxidised.

Cu2O(s) + H2SO4(aq) + Cu(s) + H2o (l)

Cu2O dissolves in concentration HCl to form and complex ion.

Test for carbon (IV oxide.

1.Carbon (IV) oxide can tested for by testing the gas with a damp litmus paper. If the gas is carbon (IV) oxide, then the paper will turn pink.

2. Carbon (IV) oxide can also be tested for by bubbling the gas through limewater. If the gas is CO2 then the gas will turn limewater milky.

Prediction:

 I predict that equation 2 is correct. C2uCO3 CuO(s) + CO2(g) , because after I heated the salt, the residue was black in colour, confirming the presence of CuO. I also tested the gas given off with a glowing splint. The splint wasn’t rekindled confirming that O2 wasn’t given off. I tested the gas given off with damp litmus paper. The paper turned pink because CO2 dissolves in water to give trioxocarbonate (IV) acid. I also bubbled the gas given off through limewater. The limewater turned milky due to the precipitation of insoluble calcium trioxocarbonate (IV). I am going to heat the cupric carbonate and see what colour the residue will be. If it is black, this shows that CuO is present hence equation 2 is correct and if it turns red, then it shows presence of Cu2O which mean equation 1 is correct. I will also test the gas given off with a glowing splint. If it re ignites, this shows that oxygen is given off; also proving equation 1 is correct.

Ca (OH) 2 +CO2(g) →CaCO3(s) + H2O(l)

Variables, which apply.

The independent variable is the cupric carbonate (CuCO3). The dependent variables are the oxides and the gases given off.

The quantity of CuCO3 was measured with a weighting scale in a weighing bottle.

Calculations:

Equation 1

2CuCO3(s) →Cu2O(s) + 2CO(g) +0.5O2(g)

Equation 2

CuCO3(s) →CuO(s) +CO2(g)

1 mole of gas contains 22.4dm3

Range of quantities measured for equation 2:

CuCO3→CuO + CO2(g)

1). 1.5g of CUCO3.

No of mol = 1.5\124 =0.012096774mol

Mass of CuO produced =76 x0.012096774=0.919354824g of CuO

0.012096774 :0. 012096774mol

The Independent variable is the cupric carbonate (CuCO3), which is measured with a weighting balance. The dependent variables are the mass of CuO and the volume of CO2 given off. A gas syringe was used to measure the volume of the CO2 given off while a balance was used to measure the residue copper oxide. To keep the independent variable constant, use the same amount for all your experiments. The same boiling tube should be used all throughout the experiments so that the volume of air in the tube will be the same for all the experiments.

Preliminary Study:

Equipment: Bunsen burner, cupric carbonate, litmus paper, gas syringe, boiling tube, wire gauze, safety goggles, lab coat, glowing splint, weighting beam, spatula, clamp and stand, rubber tube, tongs.

Method:

1. 0.5g of CuCo2 was measured on a weighting scale and put in a boiling tube.
2. Connect the boiling tube to a gas syringe with rubber tubing.
3. Hold the boiling tube with a clamp and stand to make it steady.
4. The boiling tube was heated over a pair of tongs. This is to check the colour of oxide left behind to help determine which equation is correct.
5. The volume of the gas given off was recorded.
6. 6.The gas was tested with a glowing splint to check if rekindles a glowing splint. If it did, this would have confirmed presence of CO
7. The gas was tested with damp blue litmus paper. The paper turned pink.
8. Water was added to the black residue. The black residue didn’t dissolve which also confirms my prediction that CuO is insoluble in water.

Suggested modification:

1. I could have passed the gas collected through a test tube containing lime water to test if the gas was CO. if it is, the lime water should turn milky due to the precipitation of insoluble calcium trioxocarbonate (IV).

Ca(OH)2(aq) + CO2(g) CaCO3(s) + H2O(l)

2. I can avoid error due to parallax by reading the volume of gas collected in the gas syringe by being on eye level with the syringe.
3. I made sure that all the CuCO3 had turned black so that all the gas will be given off by heating the test tube uniformly under a Bunsen burner.
4. For my two experiments, I used the same boiling tube so that the volume of air in the test tube wouldn’t change for the 2 experiments.

Final choice of equipment and diagram:

Equipment: Bunsen burner, blue litmus paper, gas syringe, boiling tube, wire gauze, safety goggles, lab coat, glowing splint, weighting scale, spatula, clamp stand, rubber tube, tongs.

For my final experiment, I am going to take my readings of the volume of the gas on eye level.

Method:

1. I weighed 0.5g of blue green CuCO3 on a weighting scale and put it in a boiling tube.
2. 2. I held the boiling tube with a clamp and a stand to make it steady.
3. I pushed a stopper in the boiling tube.
4. I connected a gas syringe with rubber tubing to the boiling tube by pushing the rubber tubing through the stopper of the boiling tube. I used a gas syringe to measure the volume of gas in the tube to give me a good degree of accuracy.
5. I clamped the boiling tube down with a clamp stand to make it steady so I can read accurately, the volume of gas given off.
6. I heated the boiling tube containing CuCO3 over a Bunsen burner to decompose the CuCO3 and to see what colour it changes to. This will help to determine which equation is correct.
7. After heating the chemical, which turned black. I read off the volume of gas collected.
8. I tested the gas with a glowing splint. The gas is supposed to rekindle the splint but it didn’t.
9. I also tested gas with damp litmus paper. .
10. I tried to dissolve the residue by adding water to it. It didn’t dissolve which also confirms that the residue is CuO because CuO is insoluble in water.

Results

1. The volume of gas collected in the gas syringe is 80cm3.i expected a volume of 90cm3.
2. The copper carbonate turned black after heating. This confirms that CuO is the residue.
3. When I tested the gas with litmus paper. The litmus paper turned pink from blue which confirms that the gas is CO2
4.  A glowing splint. The glowing splint didn’t re ignite. When I tested the gas with a glowing splint. This shows that the gas isn’t oxygen hence not equation 1.