Molar Mass of Magnesium hydroxide

Mg(OH)2 — 58.319 g/mol, worked out element by element.

Molar mass of Magnesium hydroxide, Mg(OH)₂

58.319 g/mol

Molecular weight 58.319 · 5 atoms per formula unit

Also known as: mg(oh)2, milk of magnesia.

So sparingly soluble that it is safe to swallow as an antacid.

How 58.319 g/mol is worked out

Mass contribution of each element
ElementAtomsAtomic massMass% of total
Oxygen215.99931.99854.87%
Magnesium124.30524.30541.68%
Hydrogen21.0082.0163.46%
Total558.319100%

M = 2 × 15.999 + 1 × 24.305 + 2 × 1.008 = 58.319 g/mol

Grams to moles for Magnesium hydroxide

Mass to moles conversions
MassMolesFormula units
1 g0.0171 mol1.033 × 10^22
10 g0.1715 mol1.033 × 10^23
25 g0.4287 mol2.582 × 10^23
50 g0.8574 mol5.163 × 10^23
100 g1.7147 mol1.033 × 10^24
250 g4.2868 mol2.582 × 10^24
58.319 g1 mol6.022 × 10^23

For any other amount, use the molar mass calculator, or the molarity calculator to make up a solution of a given concentration.

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Frequently Asked Questions

What is the molar mass of Magnesium hydroxide?

The molar mass of Magnesium hydroxide (Mg(OH)2) is 58.319 g/mol. That is the sum of the standard atomic weights of all 5 atoms in one formula unit: 2 × 15.999 + 1 × 24.305 + 2 × 1.008 = 58.319.

What is the molecular weight of Magnesium hydroxide?

58.319 — the same number as the molar mass, but as a dimensionless ratio rather than in g/mol. The two terms describe the same arithmetic, so a molecular weight of 58.32 and a molar mass of 58.32 g/mol are the same answer.

How many moles are in 100 g of Magnesium hydroxide?

100 ÷ 58.319 = 1.7147 mol. To convert any mass to moles, divide by the molar mass; to go the other way, multiply.

What is the percent composition of Magnesium hydroxide?

By mass, Magnesium hydroxide is 54.87% oxygen, 41.68% magnesium, 3.46% hydrogen. Each element's share is its total mass in the formula divided by 58.319.

How many atoms are in one formula unit of Magnesium hydroxide?

5: 2 oxygen, 1 magnesium, 2 hydrogen. One mole contains 6.02214076 × 10²³ formula units, so a mole of Magnesium hydroxide contains 5 × 6.022 × 10²³ atoms in total.