Question

A mixture of NaCl and CuCO3 was dissolved in water and the resulting slurry was filtered in to a beaker. The beaker and the filter paper were dried and weighed.
Mass of container: 54.558g
Mass of container and mixture: 56.779g
Mass of filter paper: 1.176g
Mass of filter paper and residue: 2.656g
Mass of beaker: 77.575g
Mass of beaker and dried residue: 78.875g

Mass of mixture =
Mass of NaCl =
%NaCl (w/w) =
Mass of CuCO3 =
% (w/w) CuCO3 =

Do the percentages add up to 100% in this example? Why or why not? What do you think happened?

Answer 1

The percentage adds up to 100%.

Percentages

Mass of mixture = mass of container+mixture - mass of container = 56.779 - 54.558 = 2.221 g

CuCO3 is insoluble in water. Thus:

Mass of CuCO3 = mass of beaker and residue - mass of beaker = 78.875 - 77.575 = 1.300 g

Mass of NaCl = mass of mixture - mass of CuCO3 = 2.221 - 1.300 = 0.921 g

%NaCl (w/w) = weight of NaCl/weight of mixture = 10.921/2.221 = 41.468%

% (w/w) CuCO3 = weight of CuCO3/weight of mixture = 1.300/2.221 = 58.532%

Addition of percentages = 41.468 + 58.532 = 100%

More on percentages can be found here: brainly.com/question/24159063

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