Question

9. When nitrogen gas reacts with hydrogen gas to form ammonia, 92.38 kJ of heat are givern off for each mole of nitrogen gas consumed, under constant pressure and standard conditions. What is the correct value for the standard enthalpy of reaction in the thermo- chemical equation below when 0.750 mol of hydrogen reacts? N2(g) + 3H2(s) → 2 NH3(g) 10. How many grams of copper can be cooled from 50.0 oC to 32.3 oC by the heat gain by 200 g of water that has an increase in temperature from 27.0 oC to 32.3 C. The specific heat capacity for copper and water are 0.387 J/goC and 4.184 J/g°C, respectively.

Answer 1

9)

when 1 mol of N2 reacts, 3 moles of H2 reacts

So,

for 3 moles of H2 , heat change = -92.38 KJ

So,

for 0.750 mol of H2, heat change = -92.38*0.750/3 = -23.1 KJ

Answer: -23.1 KJ

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