Question

An antacid contains 200 mg of aluminum hydroxide and 200 mg of magnesium hydroxide per capsule. How many moles of aluminum hydroxide does each capsule contain?

Answer 1

200 mg in g:

200 mg / 1000 => 0.2 g

number of moles Al(OH)3 :

molar mass = 78.00 g/mol

1 mole ---------- 78.00 g
? moles -------- 0.2 g

0.2 x 1 / 78.00 => 0.00256 moles of Al(OH)3

number of moles Mg(OH)2 :

molar mass = 58.32 g/mol

1 mole --------- 58.32 g
? moles ------- 0.2 g

0.2 x 1 / 58.32 => 0.00343 moles of Mg(OH)2

hope this helps!