# To investigate the rate at which different metal carbonates decompose (thermally) by measuring the amount of carbon dioxide produce when each metal carbonate is heated in a certain amount of time.

Gail Wingham

Chemistry Sc1 – Heating Metal Carbonates

Aim:

To investigate the rate at which different metal carbonates decompose (thermally) by measuring the amount of carbon dioxide produce when each metal carbonate is heated in a certain amount of time. When a metal carbonate is heated the bonds that join the carbon to the metal element are broken and so the amount of carbon dioxide produced certifies the rate of thermal decomposition and the reactivity of the metal carbonated.

Background Information:

Thermal decomposition is the breaking up of compounds using heat. When metal carbonates are thermally decomposed (or heated) the bonds between the metal and the carbonates are broken and carbon dioxide and metal oxides are produced.

An example of this reaction is when Calcium Carbonate (CaCO3) is heated;

CaCO3  CO2+ CaO

In this reaction from Calcium Carbonate, Carbon Dioxide (CO2) and Calcium Oxide (CaO) is produced.

Relative Atomic Mass of an element (or Relative Formula Mass if a compound) has the same number of particles.

eg. 100g of CaCO3 has the same amount of particles as 44g of CO2 and in 56g of CaO

We know that this is true because of the relative atomic mass in each compound. The relative atom mass of an element or a compound is equal to the mass in one mole of the substance.

For example:

We know that one mole of CaCO3 has a mass of 100g. This is because when this metal carbonate is thermally decomposed it produces CaO (calcium carbonate) and CO2 (calcium dioxide).

Ar(Ca)= 40                 40+16=56

Ar(O)= 16                  Mr(CaO)= 56

Ar = Relative Atomic Mass, Mr = Relative Formula Mass

Ar(C) = 12                12+32=44

Ar(O)= 16                Mr(CO2)= 44

Ar(O2)= 32

One mole of CaO=56g

One mole of CO2=44g

One mole of CaCO2=100g

One mole of any substance is equal to 6.02 x 1023 particles

Variables:

There are a variety of factors that can affect the results that I obtain in my experiment and because I want the most accurate result possible I need to assess these factors and decide what I will be my dependant data, what I will vary and what I will keep constant.

One of the first and most obvious variables is the metal carbonate I will use. This is one of the factors that I will continually change. I will have a range of five different metal carbonates because different metals have different rates of reactivity. The metal carbonates that I am going to use are;

• Sodium Carbonate
• Calcium Carbonate
• Magnesium Carbonate
• Zinc Carbonate
• Copper Carbonate

Although I will change each type of metal carbonate, the amount of molecules in each metal carbonate needs to be the same. The mass of each compound cannot be kept the same ...