Viscosity and density lab

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Viscosity and density lab

  1. 1. Go with the flow
  2. 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 wihen the screen is white.
  3. 3. 1. Measure the rate of flow of liquids and look for a relationship with concentration2. Measure the density of liquids and look for a relationship with concentration
  4. 4. Viscosity is defined as “the resistance to flow ofa liquid or gas”. Or, in other words, how thickor runny it is.A liquid with a high viscosity does not floweasily – think of honey.
  5. 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.
  6. 6.  Liquid samples: Water, Corn Syrup solutions of different concetrations Weighing cups 3ml syringe and cap– PLEASE DON’T LOSE THIS Balance Stopwatch
  7. 7. 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.
  8. 8. 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.
  9. 9. Weigh the empty cup and record the mass in your data table as the BEGINNING MASS.
  10. 10. Hold the syringe in a vertical position over the cup.Remove the plunger from the syringe.
  11. 11. 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.
  12. 12. 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.
  13. 13. Now you know what you’re going to do, let’s get started.
  14. 14. Write a heading for the experimentWrite 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.
  15. 15. 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.
  16. 16. 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 ___________.”
  17. 17. 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 Volum Beginnin Final Sample Density (secs) e (ml) g mass Mass mass (g) (g/ml) (g) (g)0% corn syrup(water)20% corn syrup33% corn syrup50% corn syrup75% corn syrup100% cornsyrup
  18. 18. 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.
  19. 19. Weigh the empty cup and record the mass in your data table as the BEGINNING MASS.
  20. 20. Hold the syringe in a vertical position over the cup.Remove the plunger from the syringe.
  21. 21. 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.
  22. 22. 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.
  23. 23. 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.
  24. 24. 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?
  25. 25. Plot a graph of Time against Density.Plot Time on the Y-axis and Density on the X- axis.
  26. 26. 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.
  27. 27. 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)
  28. 28. Congratuations.

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