Silicon carbide, commonly known as carborundum, is a very hard and abrasive substance. The compound is prepared by heating silicon dioxide in the presence of graphitic carbon:
SiO2(s) + 2C(s) --> SiC(s) + CO2(g)
How many grams of silicon carbide can be formed from 55.0 g of graphite and 20.0 g of silicon dioxide?
24
To determine the number of grams of silicon carbide that can be formed, we'll use the given balanced chemical equation:
SiO2(s) + 2C(s) --> SiC(s) + CO2(g)
First, we need to calculate the number of moles of graphite (C) and silicon dioxide (SiO2) using their respective molar masses. The molar mass of carbon (C) is 12.01 g/mol, and the molar mass of silicon dioxide (SiO2) is 60.08 g/mol.
Number of moles of graphite:
moles of C = mass of C / molar mass of C
moles of C = 55.0 g / 12.01 g/mol
Number of moles of silicon dioxide:
moles of SiO2 = mass of SiO2 / molar mass of SiO2
moles of SiO2 = 20.0 g / 60.08 g/mol
According to the stoichiometry of the balanced equation, 1 mole of silicon dioxide reacts with 2 moles of graphite to produce 1 mole of silicon carbide. Therefore, we need to compare the moles of silicon dioxide and graphite to determine the limiting reactant.
The reactant that produces fewer moles of silicon carbide will be the limiting reactant. The moles ratio is 1:2, which means it takes 2 moles of graphite to react with 1 mole of SiO2.
moles of SiC formed from limiting reactant = 0.5 * moles of SiO2
moles of SiC formed from limiting reactant = 0.5 * (moles of SiO2 = 20.0 g / 60.08 g/mol)
Finally, we can calculate the mass of silicon carbide formed using the molar mass of silicon carbide (SiC), which is 40.10 g/mol.
mass of SiC formed = moles of SiC formed * molar mass of SiC
mass of SiC formed = 0.5 * (moles of SiO2 = 20.0 g / 60.08 g/mol) * 40.10 g/mol
By substituting the calculated values into the equation, we can find the mass of silicon carbide formed from the given reactants.