The Thermal Decompasition Of Copper Carbonate

Copper has two oxides, Cu2O and CuO. Copper carbonate, CuCO3,

decomposes on heating to form one of these oxides and an equation can

be written for each possible reaction.

Equation 1: 2CuCO3 (s) > Cu2O (s) + 2CO2 (g) + 1/2O2 (g)

Equation 2: CuCO3 (s) > CuO (s) + CO2 (g)

Apparatus

1) Scales capable of weighing out 0.01g

2) An 100cm3 gas syringe with bung

3) A Test Tube

4) Bunsen burner

5) Heatproof mat

6) 0.411g Copper Carbonate

7) Safety goggles

8) Clamp and clamp stand

9) Gas syringe holder

10) Weigh boat

Background

* Cu2O is also know as known as cuprous oxide.

* It is insoluble in water and organic substances.

* It is found as the mineral cuprite in some red-coloured rocks.

* When it is exposed to oxygen, copper will naturally oxidize to cuprous oxide, but this takes a lot of time for it to happen.

* It usually turns a bright red when heated, this is something to look for in the experiment, if we see a bright red colour we know it is Cu2O.

This is what Cuprous Oxide looks like.

* CuO is also known as Cupric oxide.

* It is found in the mineral tenorite.

* It is a black solid which melts above 1200 �C.

* It can be formed by heating copper in air.

* It stays black when heated, this is different to Cuprous oxide so we could tell which is which oxide.

This is what cupric Oxide looks like.

Calculations

* Firstly I decided to work out the volume of Cu2O+2CO2 + 1/2O2, this is because I worked out that out of the equations this would be the one with the most gas given off.

* I found that the ratio of 2CuCO3 > Cu2O + 2CO2 + O2 = 2:21/2, this can be rounded down to 1:11/4,

* To work out the volume of gas given off in Cu2O+2CO2 + 1/2O2 I will do 24 x 1.25 which makes 30,

* I got the 24 as that is the volume in dm3 of one mole of gas.

* Now I need to work out the weight of CuCO3 I will need in the experiment so the gas syringe wont overflow so firstly I will then convert 30dm3 into 30000 cm3 to make it an easier sum overall.

* I will then divide by 100 as this the volume of the gas syringe, this makes 300 cm3.

* Then I will finally work out mass by dividing the molar mass of CuCO3 which is 123.5, with the 300cm33

* This then works out to be 0.41166666767g of CuCo3.

Method

Firstly weigh the CuCO3 carefully by weighing out 0.411g of the substance, taking into account the weight of the weigh boat and then after the weighed substance has been placed in the conical flask, weigh the boat again to make sure that no substance has been left over. Carry this process on if needed until 0.411g of CuCO3 is reached.

Place the weighed mass of CuCO3 into the test tube and insert the bung to make sure that no gas can escape put the gas syringe on a clamp and in a gas syringe holder and keep horizontal to make sure there is no advantage of gravity. Attach the test tube to the clamp. Light the Bunsen burner and place it on the heatproof mat, underneath the test tube.

Heat until the copper carbonate has entirely decomposed. This will

be indicated by the fact that the gas syringe will stop moving and the powder has gone either black or red.

Take the reading from the gas syringe and note down the volume of gas produced.

Repeat these stages a further 2 times, then take an average of the 3 results.

In this experiment it is imperative that the test is kept fair, this can be done in many ways. Firstly by making sure that the weighing of the CuCO3 is correct, This is important as if there is more than expected the gas syringe can read a lot higher and could be given the impression of being the other oxide. Secondly I can make sure that the bung on the test tube is pushed on tight so no gas is lost and the experiment isn’t incorrect by it. I also need to take into account that my glassware and equipment does have a percentage of error, although this should not affect my experiment too much as it will be quite clear which oxide it will be with the colour and the obvious difference in volume of gas given off.

In my experiment I will also need to think of safety as it is a key factor to keep myself safe and clear of dangers. I will need to be aware of the Bunsen burner and Bunsen burners, I will help with this by clearing the area and standing at all times. Also with a great deal of heat being applied to the test tubes they can shatter so I must wear goggles just encase they do and go in my eye.