If two moles of each reactant are available for the reaction described by the following equation, SiO2 (s) + 3 C (s) --> SiC (s) + 2 CO (g) , is the substance that is the limiting reactant. Show work

Answer 1

The limiting reactant is the reactant that you can make the least amount of products with, since you will run out of it first. For this reaction, we will choose one product and figure out how much of that product each reactant can create. The one that creates the least is the limiting reactant.

SiO2 (s) + 3 C (s) --> SiC (s) + 2 CO (g)

Let’s calculate how much SiC (s) is produced by SiO2 and C separately by using the mole ratio, which is the ratio of the coefficients in front of each molecule in your conversion. Use 1 if no coefficient is shown.

moles you have * mole ratio(want / have) = moles you want

moles SiO2 * coefficient (SiC/SiO2) = moles SiC

2 moles SiO2 * 1 SiC / 1 SiO2 = 2 moles SiC

moles C * coefficient (SiC/C) = moles SiC

2 moles C * 1 SiC / 3 C = 0.67 moles SiC

Since C(s) can produce the smallest quantity of product, it is the limiting reactant.