Which Equation Is Correct?

Volume = 24000 x Number of moles

     Therefore:                 Volume = 24000 x (2.43 x 10-3moles)

        Volume = 58.32g or 58.32ml produced from the reaction in Equation 2

• This gives us the volume for carbon dioxide as the ratio of copper carbonate to carbon dioxide is 1:1
• For equation 1 however, we must take into account the volume of oxygen. As the equation says 0.25O2 the ratio of copper carbonate to copper oxide is therefore

1: 0.25 -

Volume = (24000 x Number of moles of copper carbonate) / 4

Volume = (24000 x (2.43 x 10-3moles)) / 4

Volume of Oxygen produced = 14.58g or 14.58ml

• So if we add this onto the volume of carbon dioxide then we can say that the volume of gas produced in equation 1 should be:

Mass of carbon dioxide + Mass of oxygen

= 58.32g + 14.58g

Volume = 72.9g or 72.9ml of gas produced from the reaction in Equation 1

Definition

• I Predict that Equation 2 will be correct because this is an oxidation reaction and therefore a chemical is oxidised, in this case copper to form copper oxide. Oxygen gas would only be given off in a reduction reaction. Therefore there will be no excess oxygen produced.
• So what we should see is a volume of gas amounting to 58.32ml in the gas syringe and also a black coloured copper oxide because CuO copper oxide is black, where as Cu2O copper oxide is red. This can be used as a secondary check.
• (This information is adapted from ‘Chemistry for You’ – Ryan)

Variable Control

• There are a number of variables that could affect the experiment:

1. Temperature – To ensure that temperature remains constant when heating I shall use the same Bunsen burner and position the flame in the same place for each repetition of the experiment. The whole experiment will be performed under RTP (Room Temperature and Pressure). This is important to keep the heat on the copper carbonate constant and the heat also affects the volume of the gas by making it expand.
2. Surface Area – Although this will not directly affect the experiment the surface area will affect the time that the experiment takes. So I shall use a solid lump of Copper Carbonate with as closer shape as possible to the other ones I shall be using.
3. Pressure – I will not have the ability to keep the pressure constant all the time however I can perform all of the experiments within the same hour so as to reduce the risk of the outside air pressure changing and as this is a closed reaction the pressure will be constant throughout. This is important because the pressure will affect the amount of space that the gas occupies.

Organisation/Method

1. Set up the equipment as shown in the diagram below, making sure that there are no other chemicals in any of the equipment and also that the gas syringe is fully pressed in
2. Position the boiling tube so that the top of the blue cone of the roaring Bunsen burner flame is just touching the base of it
3. Place one of the 0.3g lumps of copper carbonate at the bottom of the boiling tube
4. Start to heat the copper carbonate
5. Wait until you are sure that the gas syringe has stopped moving before you turn off the heat. If unsure leave for another 5 minutes before checking again
6. Record the amount of gas in the gas syringe and also the colour of the remaining copper oxide in the boiling tube
7. Repeat this experiment five times using a different boiling tube each time as well as resetting the gas syringe
8. Work out average
9. From this it should be possible to calculate which equation is correct by the amount of gas produced

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Apparatus

• You will need:

• One 100ml gas syringe
• Five Large boiling tubes with bungs with holes in
• One delivery tube
• Two clamp stands

• In addition to this you will need:

• 1.5g Copper Carbonate split up into five                                                                                                                                            equal sized lumps weighing 0.3g exactly

• Apparatus set up:

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Risk Assessment

• There are two chemicals in this reaction that carry warnings:

1. Copper Carbonate (CuCO3) – Labelled as harmful if swallowed and also the dust irritates both lungs and eyes

2. Copper Oxide (Cu2O and CuO) – Labelled as harmful if swallowed and also the dust irritates both lungs and eyes

• Taking these warnings into account it will be necessary to wear safety goggles, however with the very small amounts of chemicals we are dealing with it is very unlikely that there will be any serious problems.

• If the chemicals come into contact with the eyes then they must be washed in an eye bath, if swallowed medical attention should be sought and if inhaled the person needs to stand outside in the fresh air.