If we now compare the moles of copper carbonate to the moles of gas (oxygen + carbon dioxide) given off with find that the molar ratio of the equation is 2:2:0.5 or 1:1:0.25.
So to find the gas given off given the moles of copper carbonate we multiply the moles of copper carbonate by 1 and 0.25
Moles of gas= (3.24 x 10-3x 0.25) + (3.24 x 10-3 x1)
moles of gas = 4.05 x 10-3 moles
now I shall use this formula: n=v/24000
n= mole
v=volume of gas
3.24 x 10-3= v/24000
I rearranged the formula and make v the object.
n x 24000=v
4.05x 10-3 x 24000 = 97.2cm³
Equation 2:
I shall now calculate the expected gas to be given off if equation 2
is correct.
Using 0.1 grams of copper carbonate:
Moles of copper carbonate used = mass / relative molecular mass
Mass = 0.4 grams
R.M.M of copper carbonate = 63.5 + 12 + (16 x 3) = 123.5 grams
Moles = 0.4 / 123.5 = 3.24 x 10-3
If we now compare the moles of copper carbonate to the moles of gas (carbon dioxide) given off with find that the molar ratio of the equation is 1:1.
As the equation is a 1:1 equation then the moles of gas are the same as the moles of carbon carbonate.
I shall now again use the equation above to calculate the gas produced to actual room temperature and pressure.
n=v/24000
n= mole
v=volume of gas
Moles = 3.24 x 10-3moles
3.24 x 10-3=v/24000
Then rearrange the formula to n x 24000=v
3.24 x 10-3x 24000=77.76 cm³
My two expected volumes of gas are 77.76 cm3 and 97.2 cm3, These are big enough for me to be able to use the more accurate, syringe, method of collecting gas, this should make my experiment more accurate.
Method
1. Attach the gas syringe to the clamp stand making sure it is parallel to the bench as shown in the diagram. Press on the end of the gas syringe until the gas syringe reads 0ml of gas.
2. Place the tripod on a heat mat and then place the gauze on top of the tripod then place the conical flask at the top as shown in diagram.
3. Place the bung from one end of the tube onto the top of the conical flask and attach the other end to the gas syringe.
4. Weight 0.1 grams of copper carbonate on the top-pan balance.
5. Remove bung from the conical flask and place the copper carbonate into the flask and replace the bung.
6. When the bung is secure heat the copper carbonate on a blue flame until no more gas is been released.
7. Wait 20 minutes until the gas has returned to room temperature as when it is hot it will expand and take up more volume. So to acquire a correct volume of gas we must wait for it too return to room temperature, approx 20oC, so that the volume is correct for a temperature of 20oC.
8. After 20 minutes record volume of gas.
Safety
Remember as we are using a Bunsen burner to wear goggle and a safety apron at all time and leave Bunsen burner on a safety flame when not in use
Result
Compare the recorded gas produced to out theoretical values.
Expected gas produced for equation 1= 97.2cm³
If the gas given off was between 95.00 - 100.00cm³ then equation 1 was the correct equation for the decomposition of copper carbonate.
Expected gas produced for equation 2 = 77.76 cm³
If the gas given off was between 75.00 - 80.00 cm³ then equation 2 was the correct equation for the decomposing of copper carbonate.
