Step-by-step explanation:
a) 4 K + O₂ ----> 2 K₂O
According to the equations, when 4 moles of K react with 1 mol of O₂, 2 moles of K₂O. To find the mass of the reactants and products we have to use their molar masses.
molar mass of K = 39.10 g/mol
molar mass of O = 16.00 g/mol
molar mass of O₂ = 2 * 16.00 g/mol
molar mass of O₂ = 32.00 g/mol
molar mass of K₂O = 2 * 39.10 g/mol + 16.00 g/mol
molar mass of K₂O = 94.20 g/mol
moles of K = 4 moles
moles of O₂ = 1 mol
moles of K₂O = 2 moles
mass of K = 4 moles * 39.10 g/mol
mass of K = 156.40 g
mass of O₂ = 1 mol * 32.00 g/mol
mass of O₂ = 32.00 g
mass of K₂O = 2 moles * 94.20 g/mol
mass of K₂O = 188.4 g
b) 6 HCl + 2 Al ----> 3 H₂ + 2 AlCl₃
In this reaction 6 moles of HCl will react with 2 moles of Al to give 3 moles of H₂ and 2 moles of AlCl₃.
molar mass of H = 1.01 g/mol
molar mass of Al = 26.98 g/mol
molar mass of Cl = 35.45 g/mol
molar mass of HCl = 1.01 g/mol + 35.45 g/mol
molar mass of HCl = 36.46 g/mol
molar mass of H₂ = 2 * 1.01 g/mol
molar mass of H₂ = 2.02 g/mol
molar mass of AlCl₃ = 1 * 26.98 g/mol + 3 * 35.45 g/mol
molar mass of AlCl₃ = 133.33 g/mol
moles of HCl = 6 moles
moles of Al = 2 moles
moles of H₂ = 3 moles
moles of AlCl₃ = 2 moles
mass of HCl = 6 moles * 36.46 g/mol
mass of HCl = 218.76 g
mass of Al = 2 moles * 26.98 g/mol
mass of Al = 53.96 g
mass of H₂ = 3 moles * 2.02 g/mol
mass of H₂ = 6.06 g
mass of AlCl₃ = 2 moles * 133.33 g/mol
mass of AlCl₃ = 266.66 g
Answer:
a) mass of K = 156.40 g mass of O₂ = 32.00 g mass of K₂O = 188.4 g
b) mass of HCl = 218.76 g mass of Al = 53.96 g mass of H₂ = 6.06 g mass of AlCl₃ = 266.66 g