How many kJ of heat are released when 15.75 g of Ba (s)reacts completely with oxygen gas to form BaO (s)? ΔH° = -1107 kJ.
A)63.5 kJ
B)20.8 kJ
C)114 kJ
D)70.3 kJ
E)35.1 kJ

Question

Quizplus · Accepted Answer

The reaction given is for the formation of BaO from Ba and O2, with a ΔH° of -1107 kJ per mole of BaO formed. The molar mass of Ba is approximately 137.33 g/mol. To find the heat released for 15.75 g of Ba, first calculate the moles of Ba: 15.75 g Ba * (1 mol Ba / 137.33 g Ba) = 0.1147 mol Ba. Since the ΔH° is per mole of BaO formed, the heat released is: 0.1147 mol Ba * (-1107 kJ/mol) = -127.0 kJ. However, none of the options exactly match this calculation, suggesting a possible mistake in calculation or interpretation. Re-evaluating with the correct approach: The correct calculation involves dividing the given mass by the molar mass of Ba and then multiplying by the given ΔH° value, but it seems there was an error in the final step of my explanation. The correct approach should yield a result that matches one of the provided options more closely, based on the proportion of the given mass of Ba to its molar mass and the given ΔH°. Given the discrepancy, let's correct the approach:First, calculate the moles of Ba: $ \frac{15.75 \, \text{g}}{137.33 \, \text{g/mol}} = 0.1147 \, \text{mol} $.Then, calculate the heat released using the ΔH° value: $ 0.1147 \, \text{mol} \times -1107 \, \text{kJ/mol} = -127.0 \, \text{kJ} $.Given the error in matching the result with the provided options, the correct step involves proportionally adjusting the calculation to accurately reflect the options given, indicating a mistake in the multiplication or interpretation of the final value. The correct answer should align with the options provided, suggesting a need to reevaluate the calculation steps or the interpretation of the ΔH° value in relation to the amount of substance reacted.

How Many KJ of Heat Are Released When 15