Question

An engine generates 15.7 g of nitric Oxide gas during a laboratory test. How much absorbed in producing this NO? (7 points) N. (g)+O,(g) → 2NO(g) H=180.5 kJ 5. A glass contains 250.0 g of warm water at 78.0°C. A piece of gold at 2.30°C is placed in the water. The final temperature reached by this system is 76.9°C. What was the mass of gold? The specific heat of water is 4.184 Jg'C', and that of gold is 0.129 Jg'"C'7 points)

Answer 1

Molar mass of NO,

MM = 1*MM(N) + 1*MM(O)

= 1*14.01 + 1*16.0

= 30.01 g/mol

mass(NO)= 15.7 g

use:

number of mol of NO,

n = mass of NO/molar mass of NO

=(15.7 g)/(30.01 g/mol)

= 0.5232 mol

Since Δ H is positive, heat is absorbed

when 2 mol of NO reacts, heat absorbed = 180.5 KJ

So,

for 0.5232 mol of NO, heat absorbed = 0.5232*180.5/2 KJ

= 47.22 KJ

Answer: 47.22 KJ

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