How much sodium chloride (NaCl) would need to be added to 750 milliliters of water to make a 15% solution?

Answer: 6.58g

Explanation: We are to find the mass of NaCl that can produce 15% solution in a 750ml

STEP 1:

the reaction moles

NaCl + H2O = NaOH + HCl

Therefore 1mole of NaCl reacts with 1mole of H2O

STEP 2:

convert 750ml to liter

750ml * 1L/1000ml = 0.750L

STEP3:

convert percentage concentration to mol/L

15% = 0.15mol/L

STEP 4:

find the mole

Mole = concentration * volume

0.15mol/L * 0.75L = 0.1125mol

STEP 5:

Find the mass

Mass = mole * molar mass

The molecular mass of NaCl is 23+35.5 = 58.5g/mol

Therefore:

0.1125mol * 58.5g/mol = 6.58g

Approximately: 6.6g