Question

The value of AH° for the reaction below is -1107 kJ:
2Ba(s) + O₂(g) → 2BaO(s)
How many kJ of heat are released when 5.75 g of Ba(s) reacts completely with oxygen to form BaO(s)?

Select one:
O a. 96.3
O b. 26.3
O c. 46.4
O d. 23.2
Oe. 193

Answer 1

Answer:

C

Explanation:

We can use heat stoichiometry. Thus, convert from grams of Ba to moles of Ba; and use the ΔH value to calculate the amount of heat released. Hence:

$\displaystyle 5.75\text{ g Ba}\cdot \frac{1\text{ mol Ba}}{137.33\text{ g Ba}} \cdot \frac{1\text{ mol}_{rxn}}{2\text{ mol Ba}} \cdot \frac{-1107\text{ kJ}}{1\text{ mol}_{rxn}} =-46.4 \text{ kJ}$

Therefore, about 46.4 kJ of heat was released.

In conclusion, our answer is C.