Answer:
73 g Mg(OH)₂
Explanation:
To find the mass of magnesium hydroxide, you need to (1) convert formula units to moles (via Avogadro's number) and then (2) convert moles to grams (via molar mass). Remember to arrange the conversions/ratios in a way that allows for the cancellation of units. The desired unit should be in the numerator. The final answer should have 2 significant figures because the given value (7.5 x 10²³) has 2 sig figs.
Avogadro's number:
6.02 x 10²³ formula units = 1 mole
Molar Mass (Mg(OH)₂):
58.32 g/mol
7.5 x 10²³ units Mg(OH)₂ 1 mole 58.32 g
----------------------------------- x ---------------------------- x -------------------- =
6.02 x 10²³ units 1 mole
= 73 g Mg(OH)₂
