Question

The enthalpy of combustion of solid carbon to form carbon dioxide is 2393.7 kJ/mol carbon, and the enthalpy of combustion of carbon monoxide to form carbon dioxide is 2283.3 kJ/ mol CO. Use these data to calculate DH for the reaction 2C1s21 O21g2 h 2CO1g2

Answer 1

ΔH=220.8 kJ/ mol

Step-by-step explanation:

We have to obtain the following equation:

2C (s) + O₂ (g) ⇒ 2 CO (g)

We have:

1) C (s) + O₂ (g) ⇒ CO₂ (g) ΔH= 2393.7 kJ/mol carbon

2) 2 CO (g) + O₂ (g) ⇒ 2 CO₂ (g) ΔH= 2283.3 kJ/ mol CO

In the sought equation 2 CO are formed therefore we have to multiply the equation N° 1 by 2

2× [C (s) + O₂ (g) ⇒ CO₂ (g)] ΔH= 2393.7 kJ/mol carbon × 2

2 C (s) + 2 O₂ (g) ⇒ 2 CO₂ (g)] ΔH= 4787.4 kJ/mol

Then, we have to reverse the equation N° 2 (we have to multiply the value of ΔH because two moles of CO are formed):

2 CO₂ (g) ⇒ 2 CO (g) + O₂ (g) ΔH= - 2283.3 kJ/ mol CO × 2=-4566.6 kJ/ mol

Finally we add both equations:

2 C (s) + 2 O₂ (g) ⇒ 2 CO₂ (g)] ΔH= 4787.4 kJ/mol

2 CO₂ (g) ⇒ 2 CO (g) + O₂ (g) ΔH=-4566.6 kJ/ mol

2 C (s) + O₂ (g) ⇒ 2 CO (g) ΔH= 4787.4 kJ/mol - 4566.6 kJ/ mol= 220.8 kJ/ mol