1) The standard enthalpy changes for the combustion of carbon and carbon monoxide are shown below.

 

C(s) + 02(g) -----> CO2(g)     delta H = -394 kJ mol-1

CO(g) + 1/2 02 (g) ----> CO2 (g)  delta H = -283 kJ mol -1

 

What is the standard enthlapy change in kJ for the following reaction?

 

C(s) + 1/2 02 (g) ---? CO(g)

 

A) -677

B) -111

C) +111

D) +677

 

What needs to be done to each equation:

Equation 1: flip and divide by two

 

Equation 2: Nothing already have 1/2 02 on reactant side

 

Add up all enthalpies = delta H = -111 kJ

 

2) Consider the two reactions involving iron and oxygen

 

2Fe(s) + 02(g) -----> 2FeO(s) delta H = -544 kJ

4Fe(s) + 302(g) -----> 2Fe203(s) delta H= -1648 kJ

 

What is the enthalpy change in kJ for the reaction below?

 

4FeO(s) + O2(g) ----> 2Fe2O3(s)

 

A) -1648 - 2 (-544)

B) -544 - (-1648)

C) -1648 - 544

D) -1648 - 2 (544)

 

 

A) -1648 - 2 (-544)