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
Oct 1, 2017

Answer:

#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#

Oct 1, 2017

Answer:

#"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)