a student made a 6.20% (w/v) solution by dissolving 6.20 grams of sodium chloride (salt) in an appropriate…

Explanation:

Step1: Calculate the volume of the solution

The mass - by - volume percentage ($% (w/v)$) is defined as $% (w/v)=\frac{\text{mass of solute (g)}}{\text{volume of solution (mL)}}\times100$. Given $% (w/v) = 6.20%$ and mass of solute (sodium chloride) $m = 6.20$ g. We can re - arrange the formula for $% (w/v)$ to find the volume of the solution $V$. $6.20=\frac{6.20}{V}\times100$ $V=\frac{6.20\times100}{6.20}=100$ mL

Step2: Calculate the mass of the water

Since the density of water $\rho_{water}=1.00$ g/mL and there is no volume increase when salt is added, and the volume of the solution is 100 mL (from step 1), the mass of water $m_{water}=\rho_{water}\times V_{water}$. The mass of the solute is 6.20 g. Let the mass of water be $m_{water}$. We know that the mass of the solution $m_{solution}=m_{solute}+m_{water}$. Since $% (w/v)=\frac{m_{solute}}{V_{solution}}\times 100$ and $V_{solution} = 100$ mL, $m_{solute}=6.20$ g. The mass of water $m_{water}=\rho_{water}\times V_{water}$. Since $V_{solution}=V_{water}$ (no volume change on adding salt), $m_{water}=1.00\times100 = 100$ g. The mass of the solution $m_{solution}=m_{solute}+m_{water}=6.20 + 100=106.2$ g

Step3: Calculate the density of the solution

The density formula is $\rho=\frac{m}{V}$. Here, $m = m_{solution}=106.2$ g and $V = V_{solution}=100$ mL. $\rho=\frac{106.2}{100}=1.062$ g/mL

Answer:

$1.062$