Reversing the calculations
4 marks · NormalA laboratory technician needs to prepare a solution containing 0.00250 mol of silver nitrate (AgNO₃) and wants the final concentration to be 0.0500 mol/dm³.
Write the equation used to calculate the required volume (in dm³) of solution.
Calculate the volume of solution (in dm³) required to obtain the stated concentration.
Convert your answer to part (b) into cm³.
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) volume (dm³) = moles / concentration
(b) 0.0500 dm³
(c) 50.0 cm³
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States or writes correct rearranged equation: volume (dm³) = moles / concentration.
M1 (b) · 1 mark · Applies the equation with correct values substituted. (follow-through)
A1 (b) · 1 mark · Correctly calculates the required volume (0.0500 dm³).
A2 (c) · 1 mark · Accurately converts the answer to cm³ (50.0 cm³). (follow-through)
Worked solution
a) Equation: volume (dm³) = moles / concentration
b) volume = 0.00250 mol / 0.0500 mol/dm³ = 0.0500 dm³
c) 0.0500 dm³ × 1000 = 50.0 cm³