You have 750. mL of a 1.2 M sodium chloride solution, but you need to concentrate it to 3.5 M. How much water do you need to evaporate from the solution to reach this concentration

493 mL has to evaporate

Explanation:

Step 1: Data given

Initial volume of the sodium chloride (NaCl) solution = 750 mL = 0.750 L

Molarity of the sodium chloride (NaCl) solution = 1.2 M

The concentration needed = 3.5 M

Step 2: Calculate the volume needed

To have a higher concentration we should lower the volume

C1*V1 = C2*V2

⇒C1 = the original concentration = 1.2 M

⇒V1 = the initial volume = 0.750 L

⇒C2 = the new concentration = 3.5 M

⇒V2 = the new volume needed = TO BE DETERMINED

1.2 M * 0.750 L = 3.5 M * V2

V2 = 0.257 L

To have a concentration of 3.5 M we need 0.257 L or 257 mL

Step 3: Calculate the volume of water to evaporate

750 mL - 257 = 493

493 mL has to evaporate