A sample of seawater contains 0.000245 g of sodium chloride per mL of solution. How much sodium chloride is contained in 50.0 mL of this solution?

2 Answers
SCooke
Oct 1, 2017

0.01225g

Explanation:

Using Dimensional Analysis we can set up the correct equation to find the desired result. If we want mass (grams) from a concentration and volume it is this:
(g/(mL)) xx mL) = g

0.000245g xx 50.0 = 0.01225g

Meave60
Oct 1, 2017

"50 mL" of the given "NaCl" solution contains "0.0123 g" of "NaCl".

Explanation:

This is basically a density problem, where the density is known:

"0.000245 g/mL NaCl" solution.

In this question, the mass of "NaCl" in "50 mL" of solution is unknown.

"density"="mass"/"volume"

To find mass when density and volume are known, we can rearrange the density formula to isolate mass.

"mass"="density"xx"volume"

Plug in the known values and solve for mass.

50.0color(red)cancel(color(black)("mL NaCl sol'n"))xx(0.000245"g NaCl")/(1color(red)cancel(color(black)("mL NaCl sol'n")))="0.0123 g NaCl"=1.23xx10^(-2) "g NaCl" (rounded to three significant figures)

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