Final answer:
To prepare 250 cm³ of 0.2 mol/dm³ H2SO4 from a 1.0 mol/dm³ stock solution, calculate the required volume of stock solution using C1V1 = C2V2, with C1 being 1.0 mol/dm³ and C2 being 0.2 mol/dm³. The calculation shows that 50 cm³ of stock solution is needed, which is then diluted to a total volume of 250 cm³ with distilled water.
Step-by-step explanation:
To prepare 250 cm³ of 0.2 mol/dm³ H2SO4 from a 1.0 mol/dm³ stock solution, you start by using the dilution formula C1V1 = C2V2, where C1 and V1 are the concentration and volume of the stock solution, and C2 and V2 are the concentration and volume of the desired diluted solution. Substituting the known values:
C1 = 1.0 mol/dm³
V1 = ? (the volume of stock solution needed)
C2 = 0.2 mol/dm³
V2 = 250 cm³
Plugging the values into the equation gives us:
1.0 mol/dm³ * V1 = 0.2 mol/dm³ * 250 cm³
Solving for V1 gives V1 = (0.2 mol/dm³ * 250 cm³) / (1.0 mol/dm³) = 50 cm³
So, you need to take 50 cm³ of the 1.0 mol/dm³ H2SO4 stock solution and dilute it with distilled water to a total volume of 250 cm³. After adding 200 cm³ of distilled water to 50 cm³ of the stock solution, you will achieve the desired concentration.