Question

How many mL of water would you need to make 50 mL of a of a 5 g/L solution using a 40 g/L stock solution

Answer 1

Answer is 43.75 ml water

Using the dilution formula, M_{1 *} V₁ = M₂​​​​​​ * V₂

where, M₁= concentration of the stock solution = 40g/L

V₁= volume of stock solution needed to make final solution

M₂= concentration of final solution required = 5g/L

V₂= volume of final solution required = 50ml or 50/1000 L

Substituting these values in the equation,

40*V₁ = 5*50/1000

Solving this, V₁ = 6.25 ml, which is the volume of stock required.

50ml - 6.25ml = 43.75ml is the amount of water that needs to be added.