To find out the correct formula, I will need the aid of an experiment. I will have to decompose the copper carbonate by heating and measure the amount of gas produced. The volume of gas will help me determine which equation is correct.
1. Set up the apparatus as shown below.
2. Measure out 0.25g of copper carbonate to the nearest 0.01g, remembering to turn the scales after placing the container in which to hold the copper carbonate.
3. Put the copper carbonate into a conical flask and attach a bung, which has a tube protruding from it, so that the rubber tube can be attached easily.
4. Attach the tube connected to the bung by a rubber tube, which is connected to the end of the glass syringe.
5. Make sure that the apparatus is fully connected so that the gas won’t leak out. Place conical flask on top of the tripod and turn on the Bunsen burner.
6. Leave the Bunsen burner on until the syringe end stops moving, because reaction has finished therefore no more gas will be produced. Then wait 5 minutes for the gas to cool down, the syringe end should start to move back into the syringe, this is because when gas is hot it will expand and when it cools down it will take up less volume.
7. Once the end of the syringe has stopped moving record the amount of gas produced and compare it with the estimated values of gas to be produced, whichever value the amount of gas corresponds with will show the correct equation.
Health and safety
Harmful if swallowed. Dust irritates lungs & eyes.
Copper (1) and
Copper (11) Oxide
Harmful if swallowed. Dust irritates lungs and eyes.
Aluminium, Magnesium ~ Explosive mixtures are formed.
If Swallowed:- Wash your mouth and drink a glass or two of water.
Seek medical attention.
If Dust Inhaled:- Remove victim to fresh air to reset
Seek medical attention.
If Dust or Solution get in your Eyes:- Flood the eyes with gently running tap water for 10 minutes.
Seek medical attention.
If spilt on your Skin or Clothes:- Remove contaminated clothing.
Wash the affected area thoroughly.
If spilt in Lab:- Wear Eye protection.
Scoop up as much Solid as possible without raising too much dust.
Wipe area repeatedly with a damp cloth until all solid is removed.
Disposal:- Add 1kg of sand and place in refuse.
Store:- With General Inorganic chemicals
Formulas used are:
1 mole of gas occupies 24000cm of space under standard conditions.
2CuCO (S) CuCO (s) + 2CO (g) + 1/2O (g)
According to this equation, 2 moles of CuCO will produce 21/2 moles of gas. So the ratio of copper carbonate to gas is 2:21/2.
CuCO CuO(s) + CO (g)
According to this equation, 1 moles of CuCO will produce 1 mole of gas. So the ratio of copper carbonate to gas is 1:1, to make both set of calculations become equal I am doubling the amount of copper carbonate, therefore the new ratio will be 2:2.
To determine the amount of 2CuCO to use so that I will get a sensible amount of gas, I’m going to work out the weight of 1 mole of 2CuCO and use this to work out how much gas the reaction will produce:
2CuCO = 2(63.5+12+(16×3)) =247
This number can be rounded up to 250g as such a slight difference between the real mass and the mass used here won’t make a big difference.
1 mole of gas will take up 24000cm under standard conditions.
If 250g of 2CuCO is used (250/250=1 mole of 2CuCO ) the amounts of gas produced will be:
Equation 1- 2:21/2 volume of gas produced 21/2×24000=60000cm
Equation 2- 2:2 volume of gas produced 2×24000= 48000cm
This much gas is far too much to be collected in a normal experiment and the equipment needed is too difficult to find, so I will reduce the amount of 2CuCO .
If 25g of 2CuCO is used (25/250=0.1 mole of 2CuCO ) the amounts of gas produced will be:
Equation 1- volume of gas: 60000×0.1= 6000cm
Equation 2- volume of gas: 48000×0.1= 4800cm
This is still far too much gas to be collected.
If 0.25g of 2CuCO3 is used (0.25/250=0.001mole of 2CuCO ) the amounts of gas produced will be:
Equation 1- volume of gas: 60000×0.001= 60cm
Equation 2- volume of gas: 48000×0.001= 48cm
This is a sensible amount of gas to collect. So 0.25g of 2CuCO will be used and will produce 60cm of gas or roughly 50cm of gas.
If the results of the experiment show that about 60cm of gas is produced then equation 1 is correct and if the amount of gas is about 50cm then equation 2 is correct.
Apparatus and Reasons for Choice:
I am using this method of collecting gas because the equipment is easy to find and the actual procedure to collect the gas is also simple.
A glass syringe of 100cm is used as it will collect the gas and give a result that may not be very accurate but is accurate enough to work out which equation is correct. Also glass is used because it has a very high melting point so the gas won’t melt the syringe.
A conical flask is used with a rubber bung because the bung will create an airtight seal so that gas can’t leak out or in. The glass won’t melt and won’t react with the chemical substance.
Tripod- holds the conical flask above Bunsen burner.
Bunsen Burner- used as heat source
Gauze mat- to place over tripod and to make sure that the heat is more evenly distributed, also makes sure that the conical flask doesn’t fall through the tripod.
Clamp- to hold syringe in place.
Rubber tubing is used as it is flexible and can create an airtight seal connecting the conical flask and syringe.
Spatula- used for measuring out the amount of copper carbonate.
Goggles- used for safety
The leakage of gas, however many precautions you take under normal circumstances, can’t ensure that there will be no leakage of gas. Some of the gas will escape.
The syringe is not totally accurate and there may be some human error whilst the syringe is being read, also it may be difficult to judge when exactly the gas will have cooled down and it may not have cooled down in 5 minutes.
The weight of the CuCO measured may not be totally accurate as it is measured to the nearest 0.01g.
The Bunsen burner may be turned off too quickly if it seems as if the reaction has stopped because the movement of the cylinder end has slowed down so much it seems to have stopped.
An apron must be worn as well as goggles. Also the tripod must not be touched straight after the experiment as it may still be hot and may cause burns.
Longman Study Guides, Chemistry.
Cambridge Advanced Sciences, Chemistry 1.
www.S-Cool.com, A and AS level Chemistry.