You must use unit analysis to solve density problems in chemistry. Remember you are learning the process of unit analysis not simply finding the correct answer!
Use the technique you have learned in problem solving: what are you looking for, what are you given, put the units together to cancel and solve.
Example #1
A sample of a known metal is dropped into a graduated cylinder with 25.0 mL of water. The level rises to 31.5 mL. If the given density of the metal is 2.56 kg/L, what is the mass of the sample in grams?
Example #2
What is the volume of a sample of aluminum in L that weighs 56.7 g? The density of aluminum is 2.71 g/mL.
Possible Questions
Why flip the density? To make sure the units of volume will be in the numerator.
I got a different answer, why? Remember that 2.71 is in the denominator. You must divide not multiply. You can either punch in 56.7 first or start with 1/2.71.
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