Question

A sample of seawater contains 6.277g of sodium chloride per liter of solution. How many mg of sodium chloride would be contained in 15.0 mL of this solution?

Answer 1

Hint: We may attempt this question by starting with the unit conversion of gram to milligrams and liter to milliliters as per asked and then further move on to unitary method.

Complete answer:
We have been given that seawater contains 6.277g of NaCl in 1L of solution i.e., $6.277g/L$
Also, $1g=1000mg\text{ and }1L=1000mL$
Therefore, as per requirement we will begin with the unit conversion:-
-g to mg: $6.277g/L\times \dfrac{1000mg}{1g}=6.277\times {{10}^{3}}mg/L$
-L to mL: $6.277\times {{10}^{3}}mg/L\times \dfrac{1L}{1000mL}=6.277mg/mL$
This means that \[6.277g/L=6.277mg/mL\]
So, now we can say that seawater contains 6.277mg of NaCl in 1mL of solution.
15mL of this solution will contain = $15mL\text{ of solution }\times \dfrac{6.277mg}{1mL\text{ of solution}}=94.155mg\text{ of NaCl}$
Therefore, 94.155 milligrams of Sodium Chloride would be contained in 15 milliliters of solution.

Additional Information:
Seawater is a mixture of 96.5 percent water, 2.5 percent of salts, and a smaller amount of various other substances including dissolved inorganic and organic particles. Seawater is a rich source of various commercially important chemical elements. The pH of seawater is limited to a range of 7.5 to 8.4. Also seawater contains comparatively more dissolved ions than all types of freshwater available on Earth (along with microbial contents).

Note:
Always remember to convert the given units into the units you are asked for. Also, while solving the numerical, write the terms along with its unit so that you can easily cancel them out and get the result in the desired unit term.