Concentrations of solutions
3 marks · EasyThe following table shows the amounts and volumes for three different solutions of lead(II) nitrate.
| Sample | Amount (mol) | Volume (dm³) |
|---|---|---|
| A | 0.10 | 0.50 |
| B | 0.20 | 0.80 |
| C | 0.04 | 0.20 |
Calculate the concentration, in mol/dm³, for sample A.
Calculate the concentration for sample B.
Which sample has the highest concentration?
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 0.20 mol/dm³
(b) 0.25 mol/dm³
(c) B · must show B
Common mistakes: Wrong units for volume; Incorrect division order
Show mark scheme and worked solution
Marking points
A1 (a) · 1 mark · Correct calculation for A: 0.10/0.50 = 0.20 mol/dm³.
A2 (b) · 1 mark · Correct calculation for B: 0.20/0.80 = 0.25 mol/dm³.
B1 (c) · 1 mark · States 'B' as sample with highest concentration.
Worked solution
a) For A: concentration = amount / volume = 0.10 / 0.50 = 0.20 mol/dm³
b) For B: 0.20 / 0.80 = 0.25 mol/dm³
c) Sample B has the highest concentration (0.25 mol/dm³ > 0.20 mol/dm³ and 0.20 mol/dm³ for C).