Final answer:
When 38.5 g of CH₄ is burned, 2137.76 kilojoules of heat are released.
Step-by-step explanation:
According to the given balanced equation:
CH₄(g) +20₂ (g) → CO₂ (g) + 2H₂O (1) +890.4 kJ
We can see that when 1 mol of methane is burned, 890.4 kilojoules of heat energy is released. To find out how many kilojoules of heat are released when 38.5 g of CH₄ is burned, we need to calculate the number of moles of CH₄.
First, we calculate the molar mass of CH₄:
C: 12.01 g/mol, H: 1.008 g/mol
Molar mass of CH₄ = 12.01 g/mol + 4(1.008 g/mol) = 16.04 g/mol
Next, we use the conversion factor to find the number of moles:
Number of moles = mass (g) / molar mass (g/mol)
Number of moles = 38.5 g / 16.04 g/mol = 2.4 mol
Finally, we multiply the number of moles by the heat released per mole:
Heat released = number of moles × heat released per mole
Heat released = 2.4 mol × 890.4 kJ/mol = 2137.76 kJ
Therefore, 2137.76 kilojoules of heat are released when 38.5 g of CH₄ is burned.