To prepare a solution of sucrose you need the grams, and grams is molarity × volume in litres × 342.297 g/mol. A litre of 1 M takes 342.297 g; 500 mL of 0.1 M takes 17.115 g; 250 mL of 0.01 M takes 855.74 mg. Enter the strength you want and the volume you want it in, and the calculator returns the mass to weigh together with the same figure in milligrams and as a percentage strength.
The figure comes from the formula. Sucrose is 12 × 12.011 (C) + 22 × 1.008 (H) + 11 × 15.999 (O), which is 342.297 g/mol, taking standard atomic weights, and every page here computes that sum rather than quoting it. Oxygen makes up the largest share of the mass: 11 of the 45 atoms in a formula unit are oxygen, and they account for 175.989 g of the 342.297 g, or 51.41% by mass. The derivation table below breaks the whole molecule down element by element.
Order of operations matters more than precision here. Dissolve the solid in rather less than the final volume, then make up to the mark once it has all gone into solution and come back to room temperature — warm solutions read low when they cool. If the calculated mass is under about 20 mg, prepare ten times the strength and dilute it tenfold by pipette instead, because C₁V₁ = C₂V₂ carries less error than a marginal weighing.
Table sugar, a disaccharide of glucose and fructose. Sugar solutions are quoted in degrees Brix, which is percent by weight rather than molarity. At 342.297 g/mol it is heavier than 19 of the 21 organic compounds covered here, and that ranking matters more than it looks: EDTA has a molar mass of 292.244 g/mol, so a gram of it contains 17.1% more formula units than a gram of sucrose. Weigh by mass and you are not weighing equal amounts of substance.
Two practical things move the result. Purity below 100% means the weighed mass overstates how much compound you have — at 98% assay, 6.8459 g of every 342.297 g is not the compound — and any water picked up from the air does the same. Both are systematic, so they shift every solution made from that jar in the same direction.
The formula
c- The molarity you want, in mol/L
V- The volume you want to make, in millilitres
342.297- The molar mass of sucrose in g/mol, derived from its formula
m- The mass of sucrose to weigh out, in grams
How it works, step by step
- Enter the molarity you want, in mol/L.
- Enter the volume you want to make, in millilitres.
- The two are multiplied together and by 342.297 g/mol.
- The result is the mass to weigh; dissolve it in part of the volume and then make up to the mark.
Worked examples
250 mL of 0.1 M sucrose
Weigh 8.55743 g. That is 0.1 M × 0.25 L × 342.297 g/mol, and it comes to 8557.43 mg if your balance is set to milligrams. Dissolve in about 175 mL first, then make up to 250 mL.
500 mL of 0.5 M sucrose
Weigh 85.5743 g. That is 0.5 M × 0.5 L × 342.297 g/mol, and it comes to 85,574.2 mg if your balance is set to milligrams. Dissolve in about 350 mL first, then make up to 500 mL.
1000 mL of 1 M sucrose
Weigh 342.297 g. That is 1 M × 1 L × 342.297 g/mol, and it comes to 342,297 mg if your balance is set to milligrams. Dissolve in about 700 mL first, then make up to 1000 mL.
How to read your score
Frequently asked questions
What is the molar mass of sucrose (C12H22O11)?
It is 342.297 g/mol. That is the sum of the standard atomic weights of every atom in the formula: 12 × 12.011 (C) + 22 × 1.008 (H) + 11 × 15.999 (O). One mole of sucrose therefore weighs 342.297 g, and a gram of it is 2.9214 mmol.
What percentage of sucrose is oxygen?
51.41% by mass. Each formula unit contains 11 oxygen atoms contributing 175.989 g of the 342.297 g total, so 100 g of sucrose contains 51.41 g of oxygen and a kilogram contains 514.14 g of it.
How much sucrose do I need for 1 litre of 1 M solution?
342.297 g — the molar mass in grams, which is what a 1 molar solution means. For 1 L of 0.1 M it is 34.2297 g, and for 1 L of 0.01 M it is 3.42297 g.
How much for 100 mL of 0.1 M?
3.42297 g. The volume is a tenth of a litre and the strength a tenth of molar, so the mass is a hundredth of 342.297 g. In milligrams that is 3422.97 mg.
Do I dissolve the solid first or make up the volume first?
Dissolve first, in perhaps 70% of the final volume, then make up to the mark. Adding solid to a full flask overshoots the volume and leaves the solution weak, and undissolved solid at the mark means the strength keeps changing as it goes in.
Can I dilute a stock solution instead of weighing?
Yes, and it is more accurate for small amounts. C₁V₁ = C₂V₂: to get 500 mL of 0.01 M from a 0.5 M stock, take 10 mL of stock and make up to 500 mL. Weighing the 1711.5 mg that 500 mL of 0.01 M needs directly is the harder of the two.
Solution recipes for sucrose
| Element | Atoms | Atomic weight | Contribution (g/mol) | By mass |
|---|---|---|---|---|
| Oxygen (O) | 11 | 15.999 | 175.989 | 51.41% |
| Carbon (C) | 12 | 12.011 | 144.132 | 42.11% |
| Hydrogen (H) | 22 | 1.008 | 22.176 | 6.479% |
| Total — one mole of sucrose | 342.297 | 100% |
Standard atomic weights, IUPAC 2021. The contribution column is atoms × atomic weight, and the total is the molar mass this page uses: 342.297 g/mol.
| Target | for 100 mL | for 250 mL | for 500 mL | for 1 L |
|---|---|---|---|---|
| 0.001 M | 34.2297 mg | 85.5743 mg | 171.149 mg | 342.297 mg |
| 0.005 M | 171.149 mg | 427.871 mg | 855.743 mg | 1.71149 g |
| 0.01 M | 342.297 mg | 855.743 mg | 1.71149 g | 3.42297 g |
| 0.05 M | 1.71149 g | 4.27871 g | 8.55743 g | 17.1149 g |
| 0.1 M | 3.42297 g | 8.55743 g | 17.1149 g | 34.2297 g |
| 0.15 M | 5.13446 g | 12.8361 g | 25.6723 g | 51.3446 g |
| 0.2 M | 6.84594 g | 17.1149 g | 34.2297 g | 68.4594 g |
| 0.25 M | 8.55743 g | 21.3936 g | 42.7871 g | 85.5743 g |
| 0.5 M | 17.1149 g | 42.7871 g | 85.5743 g | 171.149 g |
| 1 M | 34.2297 g | 85.5743 g | 171.149 g | 342.297 g |
| 2 M | 68.4594 g | 171.149 g | 342.297 g | 684.594 g |
Each cell is molarity × volume in litres × 342.297 g/mol. Dissolve the solid first and then make up to the marked volume — adding solid to a full volume overshoots it.
| Compound | Formula | Molar mass (g/mol) | Millimoles in 1 g |
|---|---|---|---|
| Uric acid | C5H4N4O3 | 168.112 | 5.9484 |
| Glucose | C6H12O6 | 180.156 | 5.5507 |
| Aspirin | C9H8O4 | 180.159 | 5.5507 |
| Caffeine | C8H10N4O2 | 194.194 | 5.1495 |
| EDTA | C10H16N2O8 | 292.244 | 3.4218 |
| Sucrose (this page) | C12H22O11 | 342.297 | 2.9214 |
| Cholesterol | C27H46O | 386.664 | 2.5862 |
Ordered by molar mass. The last column is 1000/M, which is the number a weighed gram actually gives you.