If 6.0 mol of HF is added to 4.5 mol SiO 2 , which is the limiting reactant?

Question

Silicon dioxide (quartz) is usually quite unreactive but reacts readily with

hydrogen fluoride according to the following equation.

SiO 2 (s) + 4HF(g)-------------SiF 4 + 2H 2 O(l)

Answer 1

SiO₂ (s) + 4HF(g) ==> SiF₄ + 2H₂O(l)

An easy way to identify the limiting reactant is to find moles of each reactant and divide that by the coefficient for that reactant in the balanced equation. The value that is lowest identifies the limiting reactant.

In the current problem, we have...

HF: 6.0 mol HF (÷4 -> 1.5)

SiO₂: 4.5 mol SiO₂ (÷1 -> 4.5)

The value for HF (1.5) is less than that for SiO₂ (4.5), so HF IS LIMITING.