Most chemical reactions will either absorb heat or release heat. A reaction that absorbs heat is an endothermic reaction, whereas a reaction that releases heat is an exothermic reaction. The release or absorption of heat is known as the heat of reaction. Using the heat of reaction, a stoichiometry calculation can be performed to determine the amount of heat either produced or required for a reaction to occur. Calculate the change in energy (in kJ) for the reaction shown below, if you begin with 12 grams of hydrogen (H2), and the ΔHrxn = −572 kJ. 2 H2(g) + O2(g) → 2 H2O(g)
A) -3.4 × 10³ kJ
B) 3.4 × 10³ kJ
C) 1.7 × 10³ kJ
D) -1.7 × 10³ kJ