Figure 1.01a: (a.)The surface of a single grain of table salt.

CRS Question, 6–22

QUESTION

The following reaction depicts one way in which nitric acid could be formed:

N2O5 + H2O ® 2 HNO3 DH = ?

Use the following information, and apply Hess’s Law, to determine the missing value.

H2 + 1/2 O2 ® H2O; DH = –285.8kJ

½ N2 + 3/2 O2 + ½ H2 ® HNO3; DH = –174.1 kJ

2N2 + 5 O2 ® 2 N2O5; DH = + 28.4kJ


	HMClass Present: Hess’s Law