Silicon dioxide reacts with carbon upon heating to produce silicon carbide (sic) and carbon monoxide. sio2 (s) + 3c (s) → sic (s) + 2co (g)

a. what mass of carbon is required to react completely with 15.70 g of sio2?

b. when 152 g of sio2 reacts with excess carbon, what mass of sic is produced?

c. if 42.2 g of co were produced by this reaction, what mass of carbon must have reacted?

Q1)

the balanced equation is;

SiO ₂ (s) + 3C (s) → SiC (s) + 2CO (g)

stoichiometry of SiO ₂ to C is 1:3

mass of SiO₂ reacted - 15.70 g

molar mass of SiO₂ - 60 g/mol

Number of SiO₂ moles that reacted - 15.70 g / 60 g/mol = 0.26 mol

Then the number of C moles that reacted - 0.26 mol x3 = 0.78 mol

Mass of C required - 0.78 mol x 12 g/mol = 9.36 g

Q2)

Stoichiometry of SiO₂ to SiC is 1:1

SiO₂ is the limiting reactant, therefore amount of product formed depends on amount of SiO₂ reacted.

Number of SiO₂ moles reacted - 152 g / 60 g/mol = 2.53 mol

Therefore number of SiC moles formed - 2.53 mol

molar mass of SiC - 40 g/mol

Mass of SiC formed - 2.53 mol x 40 g/mol = 101.2 g

Q3)

Stoichiometry of C to CO is 3:2

Molar mass of CO - 28 g/mol

Number of CO moles formed - 42.2 g / 28 g/mol = 1.5 mol

2 mol of CO formed when - 3 mol of C reacts

When 1.5 mol of CO are formed - 3/2 x 1.5 mol = 2.25 mol of C reacted

therefore 2.25 mol of C reacted

Mass of C reacted - 2.25 mol x 12 g/mol = 27 g