SME
Grade 10 Science · Chemistry
Solutions: solubility, concentration and molarity
Use this for “0.5 mol of solute is dissolved to make 2 L of solution. What is the molarity?”
Diagram
Molarity is moles per liter: 0.5 mol in 2 L is 0.25 mol/L.
Each dot is 0.02 mol of NaCl: 25 dots.
This is an example. Type your own values to start a new problem.
M (mol/L)
=
n (mol)
V (L)
Formulas
M
=
n
V
0.25 = 0.5/2
Assumptions
•
Molarity is moles of solute per liter of solution, not of water: 1 M = 1 mol/L.
•
Change mL to L first: 1 L = 1000 mL.
Step-by-step
WE KNOW
n = 0.5 mol, V = 2 L
FIND
molarity (M)
Step 1 · Find molarity (M)
Use M = n/V
Molarity is moles of solute per liter of solution.
M
=
0.5/2
M
=
0.25
mol/L
Check
Put the numbers back in. Both sides should match.
0.25 = 0.5/2 ✓
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.
Refresh
More problem types
Molarity from grams of solute
Use this for “5.844 g of NaCl (58.44 g/mol) makes 250 mL of solution. What is the molarity?”
Diluting a stock solution
Use this for “How much 2.00 M stock makes 200 mL of 0.500 M, and how much water is added?”
Reading a solubility curve
Use this for “50 g of KNO₃ is stirred into 100 g of water at 40 °C. Is it saturated?”
Percent by mass
Use this for “15 g of sugar is dissolved in 135 g of water. What is the percent sugar by mass?”