Question

Calculate ΔHrxn for

Ca(s) + 1/2 O2(g) + CO2(g) → CaCO3(s)
given the following set of reactions:
Ca(s) + 1/2 O2(g) →CaO(s) ΔH = −635.1 kJ
CaCO3(s) → CaO(s) + CO2(g) ΔH = 178.3 kJ
_____ kJ

Answer 1

To calculate ΔHrxn for the reaction: Ca(s) + 1/2 O2(g) + CO2(g) → CaCO3(s), reverse the reaction CaCO3(s) → CaO(s) + CO2(g), multiply the second equation by 1, and add the two equations together to obtain ΔH = 89.35 kJ.

Step-by-step explanation:

To calculate ΔHrxn for the reaction: Ca(s) + 1/2 O2(g) + CO2(g) → CaCO3(s), we can use Hess's law and the given set of reactions to obtain the desired reaction.

First, we reverse the reaction CaCO3(s) → CaO(s) + CO2(g) to get -CaO(s) - CO2(g) → -CaCO3(s) with ΔH = -177.8 kJ.

Next, we multiply the second equation given (CaO(s) + CO2(g) → CaCO3(s)) by 1 to get CaO(s) + CO2(g) → CaCO3(s) with ΔH = 178.3 kJ.

Finally, we can add the two equations together to cancel out the CaO(s) and CO2(g) and obtain the desired reaction: Ca(s) + 1/2 O2(g) + CO2(g) → CaCO3(s) with ΔH = 0.5*(-177.8 kJ) + 178.3 kJ = 89.35 kJ.

Answer 2

The ΔHrxn for the given reaction is -456.8 kJ.

Step-by-step explanation:

We can calculate the ΔHrxn for the given reaction by using Hess's law and the given set of reactions. First, we need to write the balanced chemical equation for the reaction of interest:

Ca(s) + 1/2 O2(g) + CO2(g) → CaCO3(s)

We have the following reactions:

1. Ca(s) + 1/2 O2(g) → CaO(s) ΔH = -635.1 kJ
2. CaCO3(s) → CaO(s) + CO2(g) ΔH = 178.3 kJ

To find ΔHrxn, we can add the enthalpy changes of the individual reactions:

Ca(s) + 1/2 O2(g) → CaO(s) + CO2(g) ΔH = (-635.1 kJ) + (178.3 kJ) = -456.8 kJ