Moles to grams
9.01 gin 0.5 mol of H₂O
Molar mass
Molar mass. The mass of one mole in grams: add the atomic mass of every atom in the formula. Masses. Standard atomic masses to two decimals, hydrogen 1.008, every element to uranium. Typing. Ca(OH)2, (NH4)2SO4, CuSO4.5H2O and K4[Fe(CN)6] all work.
18.02g/mol
H₂O
- H× 211.19%
- O× 188.81%
- H2 × 1.0082.016
- O1 × 16.0016.00
- Total18.02 g/mol
Grams, moles, particles
Type any one. The other three fill in. Moles. From grams, particles or litres they are rounded to 3 significant figures first, as in a worked answer. 1 mol = 6.022 × 10²³ particles = 22.7 L of gas at STP (1 bar); 22.4 L at 1 atm.
0.5 mol of H₂O = 3.011 × 10²³ molecules
At 1 atm (older value): 11.20 L
Empirical formula
1. Take 100 g, so each percentage is grams. 2. Divide by the atomic mass to get moles, then by the smallest. 3. Multiply by 2, 3 or 4 if a ratio ends in .5, .33 or .25. Molecular formula. Add the molar mass: n = molar mass ÷ empirical formula mass.
%
%
%
Empirical formulaCH₂Cl49.48 g/mol
Molecular formulaC₂H₄Cl₂n = 98.96 ÷ 49.48 = 2
| Element | g in 100 g | ÷ mass | ÷ least | Whole |
|---|---|---|---|---|
| H | 4.07 | 4.038 | 2.00 | 2 |
| C | 24.27 | 2.021 | 1.00 | 1 |
| Cl | 71.65 | 2.021 | 1.00 | 1 |
Limiting reagent
1. The equation is balanced for you. 2. Each mass becomes moles, divided by its coefficient. 3. The smallest runs out first: it is the limiting reagent and sets how much product forms. Leave a mass empty if that reactant is in excess.
N₂ + 3 H₂ → 2 NH₃
- N₂1784 mol ÷ 1 = 17843.67 kg left over
- H₂4960 mol ÷ 3 = 1653Limiting
Formed
- NH₃3307 mol56.3 kg
The NCERT way
mass (g) = moles × molar mass (g/mol)
What is the mass of 0.5 mol of water, H₂O?
- Molar mass of H₂O = 2 × 1.008 + 16.00 = 18.02 g/mol.
- Mass = moles × molar mass = 0.5 × 18.02 = 9.01 g.
- 0.5 mol of H₂O has a mass of 9.01 g.
Moles to grams: quick answers
How do you convert moles to grams?
Multiply the number of moles by the molar mass of the substance. The molar mass in g/mol is the sum of the atomic masses in the formula.
What is the mass of 0.5 mol of water?
Water, H₂O, has a molar mass of 18.02 g/mol, so 0.5 mol of it is 0.5 × 18.02 = 9.01 g.
What is the mass of 1 mol of a substance?
It is the molar mass written in grams. One mole of water is 18.02 g and one mole of carbon dioxide is 44.01 g.