| Problem: You
are given two unknown liquids. Find the density of each. Materials:
100ml graduated cylinder, triple beam balance, calculator, 2 unknown liquids.
Procedure: 1) Find the mass of the empty graduated cylinder.
2) Pour unknown liquid #1 into the graduated cylinder to the 50 ml.
level. 3) Find the mass of the graduated cylinder with 50ml of unknown liquid
#1. 4) Repeat steps 1-3 for unknown liquid #2.
We can calculate density of a liquid using the formula: Density=
Mass/Volume where mass is that
for just the liquid (you must subtract out the mass of the graduated cylinder).
Now let's calculate the densities
of the two liquids using the following given data. Liquid
#1: Given: Mass of empty graduated
cylinder = 78 grams Mass of graduated cylinder
with unknown liquid #1= 128 grams. Find:
a) Mass of just the liquid = ____
b) Volume of liquid=_____
c)
Density of liquid #1 =____ Liquid #2: Given:
Mass of empty graduated cylinder = 78 grams Mass
of graduated cylinder with unknown liquid #2= 117.5 grams. Find:
a) Mass of just the liquid = ____
b) Volume of liquid =_____
c)
Density of liquid #2=____ Check
your answers by inserting the value in the box below. Density of
Liquid 1: If you need a calculator one is available. Click
on calculator in right frame.
Density
of Liquid 2: If you need a calculator one is available. Click
on calculator in right frame.
What
is each liquid? Using the table below it is now possible for you
to determine what each liquid is. Densities for some common
liquids are:
| Substance | Density
(gm/cu.cm) | | Water | 1.00 |
| Cooking oil | 0.92 |
| Sea Water | 1.025 |
| Carbon tetrachloride | 1.58 |
| Benzene | 0.87 |
| Glycerin | 1.26 |
| Methanol | 0.79 |
Unknown liquid #1 is: Unknown liquid #2 is:
FINDING THE DENSITY OF A LIQUID
USING A HYDROMETER The density of a liquid
can also be measured using a simple device known as a hydrometer. Literally
meaning "water measurer," a hydrometer is an instrument comprised of
a vertical scale inside a sealed glass tube weighted at one end. It's used to
measure the ratio (called specific gravity) of the density of a liquid grape to
that of pure water. A hydrometer is basically a sealed
tube which is narrow at the top and is weighted with a dense material such as
lead at the bottom. You may have seen one in a salt-water fish aquarium. The hydrometer
is often considered the most valuable tool in wine making.
When a hydrometer is inserted into a liquid, the tube floats vertically so that
the narrow part sticks out of the liquid while the heavy end sinks. The narrow
part is calibrated for the density. The hydrometer floats higher in liquids of
higher density and lower in liquids of lower density. Please
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