Question

If 0.10 mole of SiO2 and 0.20 mole HF are combined in the reaction
SiO2 + 4HF => SiF4 + 2H2O
which of these statements is FALSE?

A. HF is the limiting reactant.
B. Some SiO2 will be left over.
C. The theoretical yield of SiF4 is 0.10 mole.
D. More HF would be needed to ensure that all the reactants are used up.
E. The theoretical yield of H2O will be 0.10 mole.

Answer 1

4 moles of HF requires 1 mole of Sio2 4:1 ratio

0.2 moles of HF requires 0.2/4 =0.05 moles of Sio2

so 0.05 moles of Sio2 is left over

1mole of Sio2 yields 1 mole of Sif4

so 0.05 moles yields only 0.05 moles of SiF4 hence

C. The theoretical yield of SiF4 is 0.10 mole.