Question

Methane is burned in a constant pressure system based on the following equation,

CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l), Δh = -890kJ.
How much heat (in kJ) is released when 7.63g of methane is burned ?

Answer 1

When 7.63 g of methane is burned, about 423.14 kJ of heat is released. This is calculated through stoichiometric techniques, taking into account the molar mass of methane and the heat released per mole.

Step-by-step explanation:

The question asks how much heat is released when 7.63 g of methane is burned. This type of problem is a stoichiometric calculation with an enthalpy change, which is typical in high school chemistry classes. Given that the combustion of methane is an exothermic reaction, releasing 890.4 kJ of heat per mole of methane, we can calculate the heat released for any mass of methane by using its molar mass.

The molar mass of methane (CH4) is approximately 16.04 g/mol. To find out how many moles of methane 7.63 g represents, we use the formula:

Moles of methane = mass (g) / molar mass (g/mol)

Moles of methane = 7.63 g / 16.04 g/mol = 0.475 mol

Since 1 mol of methane releases 890.4 kJ, we multiply the moles of methane by this amount to find the total heat released:

Heat released = moles of methane × heat released per mole

Heat released = 0.475 mol × 890.4 kJ/mol = 423.14 kJ

Therefore, when 7.63 g of methane is burned, approximately 423.14 kJ of heat is released.