| 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. | 
