## Chemistry: Molecular Approach (4th Edition)

$$7.54\%$$
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: $$Percent \space by \space mass = \frac{ 7.54 \space g \space NaCl }{100 \space g \space solution} \times 100\% = 7.54 \%$$