Question

A mixture of bases can sometimes be the active ingredient in antacid tablets. If 0.4889 g of a mixture of Al(OH)3 and Mg(OH)2 is neutralized with 17.06 mL of 1.000 M HNO3, what is the mass % of Al(OH)3 in the mixture?

Answer 1

Suppose x g of Al(OH)3 are present. Mass of mixture is 0.4889 g. Mass of Mg(OH)2

The molar masses of Al(OH)3 and Mg(OH)2 are 78 g/mol and 58.3 g/mol.

Number of moles of Al(OH)3

Number of moles of hyroxide ions from Al(OH)3

Number of moles of Mg(OH)2

Number of moles of hydroxide ions from Mg(OH)2

Total number of moles of hydroxide ions ......(1)

Number of moles of protons = number of moles of HNO3 .....(2)

But (1)=(2)

Mass of Al(OH)3 in sample is 0.069 g.

Mass percent of Al(OH)3 in sample