Calculate molar concentration

Supplied materials

• All measurements and observations below are supplied classroom examples. They are not data from actual learners or a claim about a particular real site.
• Paper or browser document; an ordinary calculator is optional.
• Rule: Molarity equals solute moles divided by solution liters. Formula: a/b. Variable key: a = solute amount (mol), b = solution volume (L)
• Distinct worked inputs and result: A distinct solution model has 0.9 mol in 3 L: 0.9/3=0.3 mol/L.
• Assessment case 1: Supplied case 1: solute amount (mol)=0.6; solution volume (L)=2, using the explicitly named quantities. Molarity equals solute moles divided by solution liters. What result follows?
• Assessment case 2: Supplied case 2: solute amount (mol)=1.2; solution volume (L)=3, using the explicitly named quantities. Molarity equals solute moles divided by solution liters. What result follows?
• Assessment case 3: Supplied case 3: solute amount (mol)=0.8; solution volume (L)=4, using the explicitly named quantities. Molarity equals solute moles divided by solution liters. What result follows?
• Assessment case 4: Supplied case 4: solute amount (mol)=1.5; solution volume (L)=5, using the explicitly named quantities. Molarity equals solute moles divided by solution liters. What result follows?
• Assessment case 5: Supplied case 5: solute amount (mol)=2.4; solution volume (L)=6, using the explicitly named quantities. Molarity equals solute moles divided by solution liters. What result follows?
• Assessment case 6: Supplied case 6: solute amount (mol)=3.5; solution volume (L)=7, using the explicitly named quantities. Molarity equals solute moles divided by solution liters. What result follows?

Learn the idea

Molarity is moles of solute per liter of solution, not per liter of solvent before mixing. Use supplied hypothetical measurements only; no chemical preparation is required.

Molarity equals solute moles divided by solution liters. The formula in the supplied model is a/b. Variable key: a = solute amount (mol), b = solution volume (L). Use final solution volume. Moles and grams are different units.

A distinct solution model has 0.9 mol in 3 L: 0.9/3=0.3 mol/L. Do not assume solute volume is zero in actual preparation. Track the quantity and unit before calculating. Explain the meaning of a positive, negative or fractional result when relevant. A numerical answer supports the stated model calculation; broader claims require the additional measurements and assumptions described here.

1. Name the measured quantities and their units before substituting values.
2. Write the stated rule and use the variable key to match each symbol to its explicitly named quantity.
3. Calculate each supplied case separately, keeping intermediate arithmetic and the result unit.
4. Explain the result in context and identify the assumption that would invalidate direct use of the rule.

Check your reasoning

Your answer is temporary and is not saved to an account. Download your current answer before leaving or reloading. Written work on paper or in another app stays in your own file.

Take it further

Changed-input task: use the same stated model with solute amount (mol)=1.6; solution volume (L)=2. Expected result: 0.8 mol/L. Explain what changes and keep this assumption: Do not assume solute volume is zero in actual preparation.

Nothing here is saved to an account or sent to a teacher. The answer download includes your current choice and any checked feedback. It does not include choices from the separate More practice section. Download that section separately.