Aleksza/Ruscher
Chemistry
Density of Liquids Experiments
2013-14
NAME:________________________________________________________MOD:____
PARTNERS:________________________________________________SCORE:___/__65_
(3pts for neatness, organization and completeness)
Why do objects that are the same size sometimes have different weights? The
answer has to do with their DENSITY.
An object's density is determined by comparing its mass to its volume.
Density = Mass (grams) /volume (L).
d=m/v
units: grams/L
If you compare a rock and a cork that are the same size (they have equal
volume), which is heavier? The rock is, because it has more mass. The rock is
denser than the cork, then, because it has more mass in the same volume - this
is due to the atomic structure of the elements, molecules, and compounds that
make it up.
Liquids have density, too. You can perform several experiments with different
types of liquids to determine which is more dense.
Materials:
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4 - 150 ml beakers
600 ml beaker
Graduated Cylinders
Pipettes
Funnel
water
corn syrup
vegetable oil
rubbing alcohol
food coloring
scoopula
paper towels
thermometers
hot hands
hot plate
ice & cooler
large container for ice bath
Sodium Chloride (NaCl)
Sucrose (C12H22O12)
several small objects - raisins, paperclips, pennies, small corks, etc.
SAFETY:
 Although none of the materials are considered dangerous, all normal safety precautions
should be maintained.
 HOT GLASS looks like COLD GLASS!!!! Use your hot hands to pick up hot glass!!!
 Do not use rubbing alcohol by open flames/heat sources.
PART 1: Experiment 1: Sink or Swim (20 pts total)
Question Will a raisin, paperclip, penny, small cork, ball of paper, and other small objects sink
or float if they are placed in water, corn syrup and vegetable oil?
Hypothesis: (1pt) ____________________________________________________________
Pre-Lab: Write down what you think will happen when you place each object into the different
liquids. (sink, float on top, float in the middle) (2 pts)
OBJECT
CORN
SYRUP
WATER
VEGETABLE RUBBING
OIL
ALCOHOL
Procedure:
1. Label your beakers 1-water, 2-corn syrup, 3-oil and 4- alcohol.
2. Pour 150 ml of water into beaker #1, 150 ml of corn syrup into beaker #2, 150 ml of
vegetable oil into beaker #3 and 150ml of rubbing alcohol in beaker #3.
3. Gently set a raisin in each beaker. Does it sink or float? Write down what happens to
the raisin in each beaker.
4. Take the raisins out of the beakers and try a different object, such as a paperclip or
cork. Record what happens in each beaker in the data table below.
DATA TABLE FOR EXPERIMENT 1: (2 pts)
OBJECT
CORN
SYRUP
WATER
VEGETABLE RUBBING
OIL
ALCOHOL
Conclusions:
1. Were your predictions right? Explain. (3 pts)
2. Did the raisins and other objects sink and float when you expected them to?
Explain. (3 pts)
3. Did they float in one liquid and sink in another? Explain. (3 pts)
4. Why do you think they acted the way they did? (3 pts)
5. The denser a liquid is, the easier it is for an object to float on it. If one of your objects
floated in the corn syrup but sank in the water, what does that tell you about the
densities of water and corn syrup? (3pts)
Experiment 2: Mix it up (11 points total)
Question: Which is the most dense: water, corn syrup, or vegetable oil? Which is the
least dense?
Hypothesis: (1pt)____________________________________________________________
___________________________________________________________________________
PRE-LAB: Based on your results from experiment #1, predict which liquid you think is the
most dense and which you think is the least dense. Rank the liquid below. (2 pts)
LEAST DENSE:
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MOST DENSE:
Procedure:
1. Place a few drops of food coloring into the beaker of water so you will be able to tell it
apart from the other liquids.
2. Place a few drops of food coloring (different than above) in the alcohol so you will be
able to tell it apart from the other liquids.
3. Carefully pour each of the liquids into a 600 ml beaker or a large jar. Let them settle.
DATA:
1. Describe what happened? (2 pts)
2. Did the three liquids mix together or separate into layers? (1 pt)
3. Which liquid is at the bottom of the jar? (1 pt)
4. Which is at the top? (1 pt)
Conclusions:
Was your prediction right? EXPLAIN (If so, the liquid you thought was densest should be at
the bottom of the jar. The next dense will float on top of that, and the least dense will float at
the very top.) (3 pts)
PART 2: Now you know how the densities of the four liquids compare to each
other. If you want to find out the approximate density of each, you can calculate it
using this formula: Density = Mass/Volume.
On Earth we measure mass (how much of a substance there is) by calculating
weight (how heavy it is). Weigh each liquid in grams (make sure you subtract the
weight of the beaker!) and then divide that number by the volume (number of
milliliters) of the liquid. The answer is density in grams per milliliter. (Your answer
will be more exact if you use a graduated cylinder instead of a beaker to measure
the volume and weigh the liquid.)
Experiment 3: Hot and Cold (16 pts total)
You've found out how the density of water compares to the density of alcohol, oil
and corn syrup; now see if you can change the density of water itself!
Question: Does temperature change the density of water?
Hypothesis: (1pt)____________________________________________________________
Pre-Lab: Write down what you think will happen when you mix cold water and hot water. Use
density terms. (2 pts)
Procedure: (Some of this may be done for you ahead of time so that the lab can move faster)
1. Fill two beakers with 150 ml (2/3 cup) of water. Put several drops of blue food coloring
in one beaker, and several drops of red in the second.
2. Add a handful of ice to the blue water and place in an ice bath for a few minutes
3. Put the red beaker on a hot plate for a few minutes. (DO NOT TURN the hot plate on to
max heat!)
4. Remove the blue beaker from the ice bath and the red beaker from the hot plate. HOT
GLASS LOOKS LIKE COLD GLASS – use hot hands!
5. Pour some of the blue water into the 10 ml graduated cylinder or narrow glass.
6. Using a pipette, slowly add red water a drop at a time and watch what happens. (This
part may take a little practice--if you add the red water too fast you will force the colors
to mix. Hold the pipet near the surface of the water and keep trying until you get it!)
Conclusions:
1. Was your prediction right? Explain. (3 pts)
2. What happened to the colored water? (3pts)
3. Did it stay in layers? (1 pt)
4. Which layer was on the bottom? (1pt)
5. On the top? (1 pt)
6. What does this tell you about the density of hot water compared to cold water? (3
pts)
7. What would happen if you left the cylinder out until the cold water warmed up and
the hot water cooled off? (1 pt)
Experiment 4: Salty or Sweet (15 pts)
Now you know that temperature can affect the density of water. In this part of the experiment,
test to see if adding salt or sugar will make water more dense.
Questions: Will adding salt make water more dense? Will adding sugar make water
more dense? Which is denser, sugar water or salt water?
Hypothesis: (1pt)____________________________________________________________
PRE-LAB: Write down what you think will happen to the density of water if you add salt or
sugar. (3 pts)
.Procedure:
1. Fill three beakers with 150 ml (2/3 cup) of water. Add food coloring to make blue, red,
and green water.
2. Add 2 teaspoons of salt to the red beaker and stir until the salt is dissolved. Add 2
teaspoons of sugar to the blue water and stir until it is dissolved.
3. Try putting a raisin in each of the beakers. Does it float? Remove the raisins with a
scoopula.
4. Pour some of the red (salty) water into the graduated cylinder. Using the pipet, slowly
add the blue (sugar) water one or two drops at a time. Record which sinks to the bottom
and which floats on top.
5. Add the green (pure) water drop-by-drop to the other two and record what happens.
DATA:
1. Describe what happened? (2 pt)
SALT
Raisin Float
Sugar on top of
Salt
Water on top of
Sugar and Salt
SUGAR
Water
Comments
Conclusions:
1. Were your predictions correct? Explain. (3 pts)
2. Did adding salt and sugar to the water make the water more dense or less dense?
Explain (3pt)
3. Which was more dense, the salt water or the sugar water? Explain how your data
supports your answer. (3 pt)