81) According to the following thermochemical equation, what mass of HF (in g) must react in order to

Question

produce 345 kJ of energy? Assume excess SiO2.
SiO2(s) + 4 HF(g) �� SiF4(g) + 2 H2O(l) DH°rxn = -184 kJ
81)
A) 173 g B) 37.5 g C) 150. g D) 107 g E) 42.7 g

Answer 1

184 kJ is produced by 4*HF = 4*20 = 80 g HF. Therefore, to produce 345, we will need
80 x (425 kJ/184 kJ) = ? g HF.

Answer 2

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