Question

Question #3a334

Answer 1

1) 200 mL of 10 mol/L
2) Not possible to make a solution of HCl at 4 mol/L with an original solution of HCl at 2 mol/L

Explanation:

P.S. mol/L = M

Working with 10 M:

`C_1 = 10 M`
`V_1 = ?`
`C_2 = 4 M`
`V_2 = 500 mL`

Calculation using the dilution formula:

`C_1*V_1 = C_2*V_2`

`V_1 = (C_2*V_2)/C_1`

`V_1 = (4 M*500 mL)/(10M)` = 200 mL

You need 200 mL of a solution at 10 M to make 500 mL of a solution at 4 M.

1. You take 200 mL of 10 M HCl
2. You add 300 mL of distilled water to that 200 mL solution to get to 500 mL, which will have a concentration of 4 M.

For the second part involving 2 M of HCl, it is not possible to make a solution with a higher concentration from a solution with a lower concentration UNLESS you evaporate some of the water from the original solution to get the required solution.