Chemistry
Analysis
The results of the experiment show that when Hydrochloric Acid reacts with Calcium Carbonate or Calcium Oxide, an exothermic reaction takes place. An exothermic reaction gives out energy to the surroundings. From the results we can see that Calcium Oxide causes more heat energy to be released, than Calcium Carbonate, when reacted with Hydrochloric Acid.
When the Calcium Carbonate has reacted with the Hydrochloric Acid for one minute, there is an increase in temperature of 5.4°C. When the Calcium Oxide has reacted with the Hydrochloric Acid for one minute, there is an increase in temperature of 13.6°C. From the results of the experiment, the enthalpy change can be calculated.
The equation mcDT can be used to calculate the correct enthalpy of change.
Energy transferred by CaCO3 + HCl
Mass of water = 25g
Specific heat capacity = 4.2
Raise in temperature = (23.2-17.7) = 5.5°C
Mass of CaCO3 = 1.4g
mcDT = 25 x 4.2 x 5.5 = 577.5 J
This is the energy transferred through burning 1.4g of CaCO3. The mass of 1 mole of CaCO3 is (40+12+16+16+16) 100g.
Enthalpy change = 577.5 x (100/1.4) = 41250 KJ mol-1
From this experiment the value for DH°C (CaCO3) is 41250 KJ mol-1
Energy transferred by CaO + HCl
Mass of water = 30g
Specific heat capacity = 4.2
Raise in temperature = (34.3-19.8) = 14.5°
Mass of CaCO3 = 1.2g
mcDT = 30 x 4.2 x 14.5 = 1827 J
This is the energy transferred through burning 1.2g of CaO. The mass of 1 mole of CaO is (40+16) 56g.
Enthalpy change = 1827 x (56/1.2) = 85260 KJ mol-1
From this experiment the value for DH°C (CaO) is 85260 KJ mol-1
From the calculations above, the required enthalpy change can be seen as 44010 KJ mol-1. However, this result may not be as accurate as intended as some...
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