What mass of NaCl is needed to make 2.50 L of a 2.20 M of a NaCl Solution?

1 Answer
Stefan V.
Mar 4, 2018

#"321 g"#

Explanation:

All you need to know here is that the molarity of a solution tells you the number of moles of solute present in exactly #"1 L"# of the solution.

In your case, a #"2.20-M"# sodium chloride solution will contain #2.20# moles of sodium chloride, the solute, for every #"1 L"# of the solution.

So if every #"1 L"# of this solution must contain #2.20# moles of sodium chloride in order for the solution to have a molarity of #"2.20 M"#, it means that #"2.50 L"# of this solution must contain

#2.50 color(red)(cancel(color(black)("L solution"))) * "2.20 moles NaCl"/(1color(red)(cancel(color(black)("L solution")))) = "5.50 moles NaCl"#

To convert the number of moles of sodium chloride to grams, use the molar mass of the compound.

#5.50 color(red)(cancel(color(black)("moles NaCl"))) * "58.4 g"/(1color(red)(cancel(color(black)("mole NaCl")))) = color(darkgreen)(ul(color(black)("321 g")))#

The answer is rounded to three sig figs.

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