# Percent by Mass

```Percent by Mass
 Describes solutions in which a solid is dissolved in liquid
 Percent by Mass = mass of solute/mass of solution x 100
 Mass of solution is the sum of solute and solvent
 In order to maintain a sodium chloride concentration similar
to ocean water, an aquarium must contain 3.6 g NaCl per
100.0 g of water. What is the percent by mass of NaCl in
solution?
 3.6/103.6 x 100
 3.5 %
 You have 1500.0 g of a bleach solution. The percent by
mass of the solute NaOCl is 3.62 %. How many grams of
NaOCl are present?
Percent by Volume
 Both solute and solvent are liquids
 Percent by Volume = volume of solute/volume of solution x 100
 Volume of solution is the sum of solute and solvent
 Rubbing alcohol is 70% isopropyl alcohol. If you have 100
mL of rubbing alcohol, how many mL is the alcohol?
Mole Fraction
 Ratio of # of moles of solution in solution to total # of
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moles solute and solvent
XA = mole fraction for solvent
XA = nA / (nA + nB )
XB = mole fraction for solvent
XA = nB / (nA + nB )
 A solution is 37.5% HCl and 62.5% water. Determine
the mole fraction each compound.
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