Question

According to the following thermochemical equation, what mass of H2O (in g) must form in order to produce 488 kJ of energy?

Answer 1

Answer:

m = 95.47 g

Explanation:

The reaction is missing. I found it, and here's the missing part:

SiO2(s) + 4HF(s) -> SiF4(s) + 2H2O(l)        ΔH°rxn = -184 kJ

According to the reaction, 2 moles of water are produced in this reaction, and this also produces 488 kJ of energy.

To calculate the mass of any compound we use the expression:

m = n*MM

The molar mass of water is 18 g/mol. so, we need the moles of water to get the mass. The relation between the heat and energy is the following:

ΔH = Q/n ---> solving for n:

n = Q/ΔH.

So, let's calculate moles of water used here:

n = 488 * 2/184

n = 5.304 moles

Now we can calculate the mass:

m = 5.304 * 18

m = 95.47 g