Question

4.

9. Given the following thermochemical equation detailing the combustion of methane
CH4(g) + 2O2(g) → CO2(g) + 2H₂O(g) AHxn-802kJ/mol CH4
determine the amount of energy released when 25.0 g of methane undergoes combustion.
a. 1.95 x 10³ kJ
d.1250 kJ
e. 2.01 x 10¹ kJ
b. 3.12 x 10-2 kJ
c. 453 kJ

Answer 1

1250.12

Step-by-step explanation:

To determine the amount of energy released when 25.0 g of methane undergoes combustion, we need to use the given thermochemical equation and the molar mass of methane (CH4).

First, calculate the molar mass of methane (CH4):

Carbon (C): 1 atom x 12.01 g/mol = 12.01 g/mol

Hydrogen (H): 4 atoms x 1.01 g/mol = 4.04 g/mol

Molar mass of CH4 = 12.01 g/mol + 4.04 g/mol = 16.05 g/mol

Now, let's calculate the number of moles of methane in 25.0 g:

Number of moles = mass (g) / molar mass (g/mol)

Number of moles = 25.0 g / 16.05 g/mol ≈ 1.56 mol

According to the thermochemical equation, the enthalpy change for the combustion of methane is -802 kJ/mol of CH4.

To determine the energy released when 25.0 g of methane undergoes combustion, we need to multiply the number of moles by the enthalpy change:

Energy released = number of moles x enthalpy change

Energy released = 1.56 mol x (-802 kJ/mol)

Energy released ≈ -1250.12 kJ

Therefore, when 25.0 g of methane undergoes combustion, approximately 1250.12 kJ of energy is released.