Question

Calculate...

1) The number of carbon atoms in 450.0g C₁₀H₂₂

2)The number of sulfate ions in 15.65g Fe₂(SO₄)3

Answer 1

1)
molar mass of C10H22 = 142 g/mol
number of mole = (given mass)/(molar mass)
= 450.0/142
= 3.17 mole

1 mole of C10H22 has 10 mole of C
3.17 mole of C10H22 has (10*3.17) mole of C
number of mole of C = 31.7 mole
number of C atom = (number of mole of C)*(6.02*10^23)
= 31.7*6.02*10^23
= (1.9*10^25)

Answer : (1.9*10^25)

2)
molar mass of Fe2(SO4)3 = 399.9 g/mol
number of mole = (given mass)/(molar mass)
= 15.65/399.9
= 0.03913 mole

1 mole of Fe2(SO4)3 has 3 mole of SO4-2
0.03913 mole of Fe2(SO4)3 has (3*0.03913) mole of SO4-2
number of mole of C = 0.1174 mole
number of SO4-2 ion = (number of mole of SO4-2)*(6.02*10^23)
= 0.1174*6.02*10^23
= (7.07*10^24)

Answer : (7.07*10^24)