Question

The value of AH° for the reaction below is +128.1 kJ CH3OH (I)-CO (g) + 2H2 (g) How much heat is consumed when 87.1 g of hydrogen gas is formed? A) 2.76 x 103 kJ B) 5.52 x 103 kJ C) -5.52 x 103 kJ D) -2.76 x 103 kJ E) -128.1 kJ

Answer 1

Answer:

A) 2.76 x 103 kJ

Explanation:

CH3OH (I)--------->CO (g) + 2H2 (g)

Number of moles contained in 87.1g of hydrogen gas= mass of hydrogen gas/ molar mass of hydrogen gas

Molar mass of hydrogen gas= 2gmol-1

Number of moles hydrogen gas = 87.1g/2gmol-1= 43.55 moles of hydrogen

1 mole of methanol yields 2 moles of hydrogen

x moles of methanol yields 43.55 moles of hydrogen

x= 43.55 moles of hydrogen × 1 mole of methanol/2 moles of hydrogen

x= 21.775 moles of methanol

Then;

If 1 mole of methanol absorbs 128KJ of energy

21.775 moles of methanol will absorb 21.775 × 128/1 = 2.7×10^3 KJ of heat