Final answer:
The percent composition of a compound can be calculated by dividing the mass of each element by the molar mass of the compound and multiplying by 100. For example, the percent composition of KBr is 32.77% potassium and 67.23% bromine. Similarly, the percent composition of LiOH is 28.95% lithium, 66.81% oxygen, and 4.23% hydrogen.
Step-by-step explanation:
The percent composition of a compound is the percent by mass of each element in the compound. To calculate percent composition, we divide the mass of each element by the molar mass of the compound and multiply by 100. Let's calculate the percent composition for each compound:
a) KBr:
Atomic mass of K = 39.10 g/mol
Atomic mass of Br = 79.90 g/mol
Molar mass of KBr = 39.10 + 79.90 = 119 g/mol
Percent composition of K in KBr = (39.10 / 119) * 100 = 32.77%
Percent composition of Br in KBr = (79.90 / 119) * 100 = 67.23%
Therefore, the percent composition of KBr is 32.77% potassium and 67.23% bromine.
b) LiOH:
Atomic mass of Li = 6.94 g/mol
Atomic mass of O = 16.00 g/mol
Atomic mass of H = 1.01 g/mol
Molar mass of LiOH = 6.94 + 16.00 + 1.01 = 23.95 g/mol
Percent composition of Li in LiOH = (6.94 / 23.95) * 100 = 28.95%
Percent composition of O in LiOH = (16.00 / 23.95) * 100 = 66.81%
Percent composition of H in LiOH = (1.01 / 23.95) * 100 = 4.23%
Therefore, the percent composition of LiOH is 28.95% lithium, 66.81% oxygen, and 4.23% hydrogen.
c)MgCl₂ :
Atomic mass of Mg = 24.31 g/mol
Atomic mass of Cl = 35.45 g/mol
Molar mass of MgCl₂ = 24.31 + (2 * 35.45) = 95.21 g/mol
Percent composition of Mg in MgCl₂ = (24.31 / 95.21) * 100 = 25.55%
Percent composition of Cl in MgCl₂ = (2 * 35.45 / 95.21) * 100 = 74.45%
Therefore, the percent composition of MgCl₂ is 25.55% magnesium and 74.45% chlorine.
d) Al₂(SO₄)₃ :
Atomic mass of Al = 26.98 g/mol
Atomic mass of S = 32.07 g/mol
Atomic mass of O = 16.00 g/mol
Molar mass of Al₂(SO₄)₃ = (2 * 26.98) + (3 * 32.07) + (12 * 16.00) = 342.15 g/mol
Percent composition of Al in Al₂(SO₄)₃ = (2 * 26.98 / 342.15) * 100 = 15.78%
Percent composition of S in Al₂(SO₄)₃ = (3 * 32.07 / 342.15) * 100 = 28.14%
Percent composition of O in Al₂(SO₄)₃ = (12 * 16.00 / 342.15) * 100 = 56.08%
Therefore, the percent composition of Al₂(SO₄)₃ is 15.78% aluminum, 28.14% sulfur, and 56.08% oxygen.