Given the data below, use Hess\' law to calculate AH for the reaction: N2(g) + N

Question

Given the data below, use Hess' law to calculate AH for the reaction: N2(g) + NO2(g) 3 NO(g) Eq 1: Eq 2: N2(g) + O2(g) 2 NO(g) 2 NO(g) + 02(g) 2 NO2(g) H = +180.7 kJ Show all your work here: 1. Which equation did you have to reverse? - a. Eq1 b. Eq2 C. Eq 3 d. Eq 1 & Eq 2 e. None of the above 2. For which equation did you have to add a coefficient (which equation did you have to multiply)? a. Eq 1 b. Eq 2 c. Eq 3 d. Eq 1& Eq 3 e. None of the above 3, what is H for the above reaction? a. 311.3k b. 155.7 k c. -95.6 k d. 85.1 k e. None of the above 4. A positive value for AH indicates: a. b. c. d. an exothermic reaction an endothermic reaction heat is given off by the reaction the enthalpy of the products is less than the enthalpy of the reactants 5. Which of the following will have a standard enthalpy of formation equal to zero? a. H20p b. 020 c. CO@) d. NaClg) e. H29 Fall 2017

Explanation / Answer

The desired reaction can be obtained by adding the equation 1 into half of reverse equation 2 and half of equation 3.

So the enthalpy of the desired reaction will be :

=(+180.7) + (113.1 /2) + (-163.2/2)

= 155.65 KJ

On the basis of this the following questions can be answered:

Ans 1 : b) Eq 2

Ans 2 : c) Eq 3

Ans 3 :b) 155.7 KJ

Ans 4 b) an endothermic reaction

This means that the reaction ha absorbed heat . The enthalpy of products is more than that of reactants.

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