Question

consider the following reaction

2H2(g)+O2(g)--> 2H2O (I) delta H= -572KJ

A) how much heat is evolved when 1.00 mole of H2O (I) is produced?

B) how much heat is evolved when 4.03g H2 are reacted with 40.0g of O2?

C) the total volume of hydrogen gas needed to fill the Hindenburg was 2.0*10^8 L at 1.0 atm and 25 degree C. How much HEAT was evolved when the Hidenburg exploded, assuming all of the hydrogen reacted (plenty of oxygen)?

Answer 1

A) H= -572KJ this is for 2moles

so for one moles- 286KJ

B) 2H2 +O2 = 2H2O

   4g + 32g =36g SO delta H will be -572KJ

C) H2 +1/2O2 = H20

V = 2.00 × 10⁸ L

p = 1.00 atm

T = 25 °C

ΔH = -286 kJ·mol⁻¹

Calculations:

(a) Convert temperature to kelvins

T = (25.1 + 273.15) K = 298.25 K

(b) Moles of hydrogen

Use the Ideal Gas Law:

pV = nRT

n = (pV)/(RT)

n = (1.00 × 2.00 × 10⁸)/(0.082 06 × 298.25) = 8.172 × 10⁶ mol

(c) Heat evolved

q = nΔH = 8.172 × 10⁶ × (-286) = -2.34 × 10⁹ kJ

The hydrogen in the Hindenburg released 2.34e9 kJ .