Question

An antacid contains 200mg of aluminum hydroxide and 200mg of magnesium hydroxide per capsule.
a. How many moles of Al(OH)3 does each capsule contain? 2.56 x 10^-3 mol Al(OH)3 is that correct?
b. What is the mass in milligrams of 0.0457 mole of magnesium hydroxide?
2.665 x 10^-3 mg is this correct?

Answer 1

a is right.
b is not.
0.0457 x 58.32 = ? g
Change to mg. Wouldn't that be 2.665 x 10^3 mg. I would round that to 2.66E3 mg to make the number of significant figures correct at 3.