Molar Mass of Gypsum
CaSO4·2H2O — 172.164 g/mol, worked out element by element.
Molar mass of Gypsum, CaSO₄·₂H₂O
172.164 g/mol
Molecular weight 172.164 · 12 atoms per formula unit · includes 2 waters of crystallisation
Also known as: caso4.2h2o, calcium sulfate dihydrate.
Calcium sulfate with two waters of crystallisation — plasterboard, and the standard hydrate exercise.
How 172.164 g/mol is worked out
| Element | Atoms | Atomic mass | Mass | % of total |
|---|---|---|---|---|
| Oxygen | 6 | 15.999 | 95.994 | 55.76% |
| Calcium | 1 | 40.078 | 40.078 | 23.28% |
| Sulfur | 1 | 32.06 | 32.060 | 18.62% |
| Hydrogen | 4 | 1.008 | 4.032 | 2.34% |
| Total | 12 | 172.164 | 100% |
M = 6 × 15.999 + 1 × 40.078 + 1 × 32.060 + 4 × 1.008 = 172.164 g/mol
Grams to moles for Gypsum
| Mass | Moles | Formula units |
|---|---|---|
| 1 g | 0.0058 mol | 3.498 × 10^21 |
| 10 g | 0.0581 mol | 3.498 × 10^22 |
| 25 g | 0.1452 mol | 8.745 × 10^22 |
| 50 g | 0.2904 mol | 1.749 × 10^23 |
| 100 g | 0.5808 mol | 3.498 × 10^23 |
| 250 g | 1.4521 mol | 8.745 × 10^23 |
| 172.164 g | 1 mol | 6.022 × 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 Gypsum?
The molar mass of Gypsum (CaSO4·2H2O) is 172.164 g/mol. That is the sum of the standard atomic weights of all 12 atoms in one formula unit: 6 × 15.999 + 1 × 40.078 + 1 × 32.060 + 4 × 1.008 = 172.164.
What is the molecular weight of Gypsum?
172.164 — 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 172.16 and a molar mass of 172.16 g/mol are the same answer.
How many moles are in 100 g of Gypsum?
100 ÷ 172.164 = 0.5808 mol. To convert any mass to moles, divide by the molar mass; to go the other way, multiply.
What is the percent composition of Gypsum?
By mass, Gypsum is 55.76% oxygen, 23.28% calcium, 18.62% sulfur, 2.34% hydrogen. Each element's share is its total mass in the formula divided by 172.164.
How many atoms are in one formula unit of Gypsum?
12: 6 oxygen, 1 calcium, 1 sulfur, 4 hydrogen. One mole contains 6.02214076 × 10²³ formula units, so a mole of Gypsum contains 12 × 6.022 × 10²³ atoms in total.