Measuring the Density of a Sugar Solution
Introduction
The density of an object is defined as the ratio of its mass to its volume. We write this mathematically by
using the equations:
Density mass
volume
For an example of density, consider the following: Imagine a brick that is made of Styrofoam.
Imagine a second brick that is made of lead. Note that even though the bricks take up the same amount of
space - that is, they have the same volume - there is a major difference in their mass or weight. We would say
that the lead is denser, that is it has more mass in the same volume.
It is important to note that water has a density of 1 g/mL. Objects that have a density less than water,
that is, less than 1 g/mL, will float on the surface of the water. Those that have a density greater than 1 g/mL
will sink. Consider our two bricks again. The brick of Styrofoam will float if we toss it into water. The lead
will quickly sink.
Modern ship manufacturers make use of density when designing the ships they build. They use
materials that are denser than water but shape the materials so that they take up enough space to float.
Although the ships weigh several thousand tons, that weight takes up a lot of space. Overall, the ship has a
density less than water and therefore floats.
Two factors have an effect on the density of water:
1) Temperature will have a small effect on the density. For this lab, we will ignore any
temperature effects. They are negligible.
2) If more dense materials are dissolved in the water , the solution density will increase. We
will see this effect in today's lab when we measure the effect of dissolving sucrose on the
density of water.
In this experiment you will test your laboratory technique by calibrating a 10 mL graduated
cylinder, making up an aqueous sucrose solution of a particular weight percent in solute, and
measuring the density of the solution with the calibrated graduated cylinder. The density result
will be graded for accuracy and precision (7 out of the 20 points). Since the correct density will
depend on a correctly prepared sugar solution, careful sample preparation will be critical.
There are many ways of describing the concentration of a solution. The weight percent of solute
in a solution is given by the equation:
Weight % (w/w) =
