What is the mass percentage?

Question

A solution is prepared by dissolving 52.3 g of CsCl in enough water to form 502 mL of solution. Calculate the mass % of CsCl in the solution if the density is 1.12 g/mL.

Answer 1

The key to most chemistry problems is understanding that most calculations involve extensive (proportional to amount of stuff) variables or, if solving for a concentration or percentage, a ratio of extensive variables.

You are looking for the % CsCl which is the (m_CsCl/m_soln) x 100.

We need to find the numerator and the denominator and do the division:

The numerator is given.

The denominator is found from the 502 ml of soln x (1.12 g of soln/ml of soln) (Note that molarity which is focused on mole per liter of solution usually requires the density of the solution in order to convert to percentages or molality)

Now just do the division of (g CsCl/g Soln) x 100.

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