The document provides instructions for an experiment to measure how the viscosity and density of liquid solutions change with increasing concentration. Students are asked to make a hypothesis, collect data on flow time and mass for different concentration solutions, calculate density, and graph the results. They are then asked to analyze how viscosity and density relate to concentration based on their graphs and to explain these relationships using diagrams of the molecular structure in solutions at different concentrations.

1. Go with the flow

2.  While the screen is WHITE, read and plan
 When the screen is YELLOW, do what the
instructions tell you
 Everything will make more sense if you read
the instructions from beginning to end before
you start – so read when the screen is white.

3. 1. Measure the rate of flow of liquids and look
for a relationship with concentration
2. Measure the density of liquids and look for a
relationship with concentration

4. Viscosity is defined as “the resistance to flow of
a liquid or gas”. Or, in other words, how thick
or runny it is.
A liquid with a high viscosity does not flow
easily – think of honey.

5. Viscosity is a physical property of a substance.
It is due to intermolecular forces – forces
between the molecules that make the
molecules a little bit sticky.
The viscosity of a substance is the same
whether there is a lot of it or a little.

6. Density is a measure of how closely packed the
particles of a substance are. If they are all
close together, they have a high density and a
small amount of the material will have a
higher mass than if they were less dense.
More dense Less dense

7. Density is a physical property of a substance.
The density of a substance is the same whether
there is a lot of it or a little.

8.  Liquid samples: Water, Corn Syrup solutions
of different concetrations
 Weighing cups
 3ml syringe and cap– PLEASE DON’T LOSE
THIS
 Balance
 Stopwatch

9. REMEMBER – the screen is WHITE – you are
reading these instructions so that you know
the whole procedure before you start.
Do not begin until the screen turns YELLOW.

10. Fill the 3ml syringe with one of the liquids.
Adjust the level of the liquid in syringe so
that the liquid is exactly at the 3ml mark.
Place the syringe cap firmly on the syringe.

11. Weigh the empty cup and record the mass in
your data table as the BEGINNING MASS.

12. Hold the syringe in a vertical position over the
cup.
Remove the plunger from the syringe.

13. You’re going to time how long it takes for the
liquid to flow out of the syringe.
Remove the cap from the syringe and let the
liquid flow into the cup. Start the stopwatch.
Stop the stopwatch when the liquid reaches
0.5ml and record the time in your data table.

14. Weigh the cup with the liquid in it and record
the mass in your data table as FINAL MASS.
Carefully wash out the cup and the syringe.
Repeat the measurements with all of the
liquids provided.

15. Now you know what you’re going to do, let’s
get started.

16. Write a heading for the experiment
Write a sub heading: “Hypothesis”
All experiments start with a Hypothesis – a
prediction of what will happen. It doesn’t
have to be correct, it just has to a prediction
that you can TEST.

17. A simple hypothesis is often written like this:
“If …. then ….”
For example: “If the sky is blue, then it is not
raining”.
That is a hypothesis that you could test by
recording whether or not it is raining when
the sky is blue.

18. How do you think the density of liquids and
their viscosities will change if you increase
their concentration?
Write your hypothesis:
“If the concentration of the solution
increases, then the density of the solution will
_________ and the viscosity of the solution will
___________.”

19. You need to set up a data table in which to
record your results. Write a heading, “Results”
and copy this data table beneath it.
Sample Time Volume Beginning Final Sample Density
(secs) (ml) mass (g) Mass mass (g/ml)
(g) (g)
0% corn syrup
(water)
33% corn syrup
50% corn syrup
75% corn syrup
80% corn syrup
90% corn syrup

20. Fill the 3ml syringe with one of the liquids.
Adjust the level of the liquid in syringe so
that the liquid is exactly at the 3ml mark.
Place the syringe cap firmly on the syringe.

21. Weigh the empty cup and record the mass in
your data table as the BEGINNING MASS.

22. Hold the syringe in a vertical position over the
cup.
Remove the plunger from the syringe.

23. You’re going to time how long it takes for the
liquid to flow out of the syringe.
Remove the cap from the syringe and let the
liquid flow into the cup. Start the stopwatch.
Stop the stopwatch when the liquid reaches
0.5ml and record the time in your data table.

24. Weigh the cup with the liquid in it and record
the mass in your data table as FINAL MASS.
Carefully wash out the cup and the syringe.
Repeat the measurements with all of the
liquids provided.

25. Calculate the Sample Mass by subtracting the
Beginning Mass from the Final Mass. Write
your values for each solution in the data
table.
Calculate the Density of each solution by
dividing the Sample Mass by the Volume.
Write your values for each solution in the data
table.

26. Plot a graph of Time against Concentration.
The Independent Variable goes on the x-axis.
Which value did you change or choose?
The Dependent Variable goes on the y-axis.
Which value did you measure?

27. Plot a graph of Time against Density.
Plot Time on the Y-axis and Density on the X-
axis.

28. Look at your graphs. Look back at your
Hypothesis.
Was your prediction correct?
Write the heading “Conclusions” and write a
sentence commenting on your prediction now
that you’ve done your experiment.

29. Answer these questions in your conclusion:
1. What is the apparent relationship between
viscosity of your sample, as indicated by
flow time, and its density?
2. How does the time of flow relate to the
concentration of the solution?
3. Which materials do you think would flow
fastest,
 Water (density 1g/cm3)
 Alcohol (density 0.79 g/cm3)

30. Draw diagrams of the solutions to explain the
relationship between concentration and
density and viscosity.
Show the molecules in the solutions and show
how they affect density and concentration.

31. Thank you to
“The Dynamic Duo Shares Ideas on How to Teach Chemistry”
First Edition, Eva Lou Apel & Barbara Schumann