Answer
$$7.54\%$$
Work Step by Step
1. Calculate the molar mass:
$ NaCl $ : ( 22.99 $\times$ 1 )+ ( 35.45 $\times$ 1 )= 58.44 g/mol
2. Find the volume of the solution with 100 g in total:
$$100 \space g \times \frac{1 \space mL}{ 1.05 \space g} = 95.2\underline{38} \space mL$$
3. Calculate the amount of moles of $ NaCl $ for that volume:
$$ 95.2\underline{38} \space mL \times \frac{1 \space L}{1000 \space mL} \times \frac{ 1.35 \space mol \space NaCl }{1 \space L} = 0.129 \space mol \space NaCl $$
- Calculate or find the molar mass for $ NaCl $:
$ NaCl $ : ( 22.99 $\times$ 1 )+ ( 35.45 $\times$ 1 )= 58.44 g/mol
- Using the molar mass as a conversion factor, find the mass in g:
$$ 0.129 \space mole \times \frac{ 58.44 \space g}{1 \space mole} = 7.54 \space g$$
4. Calculate the percent by mass:
- Since we have used the volume for 100 g of solution:
$$Percent \space by \space mass = \frac{ 7.54 \space g \space NaCl }{100 \space g \space solution} \times 100\% = 7.54 \% $$