Worksheet: Mass Percentage

In this worksheet, we will practice calculating the mass of each component in a solution or mixture as a percentage of the total mass.


In concentrated hydrochloric acid, the HCl concentration is 12 M and the density is 1.18 g/mL. What is the weight percent (% w/w) of concentrated HCl?

  • A 1 4 %
  • B 1 2 %
  • C 9 8 %
  • D 3 7 %
  • E 5 . 1 %


Calculate the mass of salt that must be added to 150 g of water to prepare a solution that is 15.00% salt by mass.


Fill in the blank: MasspercentageofelementXmassofcompoundY=×100%.

  • AMass number of X
  • BNumber of moles of X
  • CAtomic number of X
  • DMass of X
  • ENumber of moles of Y


Iron(II) can be oxidized to iron(III) by the dichromate ion, which is reduced to chromium(III) in acidic solution.

A 2.5000 g sample of iron(II) ore is dissolved in water and the iron(II) converted into iron(III) by NaCrO227. Exactly 19.17 mL of 0.0100 MNaCrO227 is required in the titration. What percentage of the ore sample was iron?

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