Q110 E - Chemistry (OpenStax)

Question

Physiological saline concentration-that is, the sodium chloride concentration in our bodies-is approximately\(0.16{\rm{M}}\). A saline solution for contact lenses is prepared to match the physiological concentration. If you purchase \(25\;{\rm{mL}}\) of contact lens saline solution, how many grams of sodium chloride have you bought?

Step-by-Step Solution

Answer

 Therefore,

 

\(m({\rm{NaCl}}) = 0.234\;{\rm{g}}\).

Step 1: To calculate the quantity of \(NaCl\) .

First, calculate the quantity of NaCl in the solution.

 

The quantity can be number of moles of NaCl from morality and volume of solution.

 

\(n({\rm{NaCl}}) = c({\rm{NaCl}}) \cdot {\rm{V}}\)

 

\(n({\rm{NaCl}}) = 0.15\;{\rm{mol}}/{\rm{L}} \cdot 25 \cdot {10^{ - 3}}\;{\rm{L}}\)

 

\(n({\rm{NaCl}}) = 4 \cdot {10^{ - 3}}\;{\rm{mol}}\).

Step 2: To calculate the mass of \(NaCl\) .

Then, calculate the mass of the NaCl from the number of moles and molecular mass.

 

\(m({\rm{NaCl}}) = n({\rm{NaCl}}) \cdot {\rm{M}}({\rm{NaCl}})\)

 

\(m({\rm{NaCl}}) = 4 \cdot {10^{ - 3}}\;{\rm{mol}} \cdot 58.44\;{\rm{g}}/{\rm{mol}}\)

 

\(m({\rm{NaCl}}) = 0.234\;{\rm{g}}\).