What is the mass of a #"7% HCl"# solution in which #"45.0 HCl"# has been dissolved?

1 Answer
Dec 12, 2014

Answer:

The mass of the solution is #"643 g"#.

Explanation:

In this case, where the mass of the solute is known, and the mass of the solution is desired, the basic equation for percent concentration is the mass of solute divided by the mass of the solution multiplied times 100%.

#"percent concentration"## = ##"mass of solute"/"mass of solution"# x #"100%"#

Given:
mass of solute = #"45.0 g HCl"#
percent concentration = #"7.00%"#

Unknown:
mass of solution

Solution: Rearrange the equation for percent concentration to isolate mass of solution. Plug in the known values and solve.

#"mass of solution"## = ##"mass of solute"/"percent concentration"# x #"100"#

#"mass of solution"## = ##"45.0 g HCl"/(7.00color(red)cancel(color(black)("%")))# x #100color(red)cancel(color(black)("%"))# = #"643 g"# (rounded to three significant figures)