Effects of Solutes on Expansion of Frozen Water

Zack Blevins and Mikayla Rigsby3/6/17

Pre-AP Chemistry11th GradeMs. Smith

Table of contents ~

Title page ~ page 1

Table of contents ~ page 2

Acknowledgements ~ page 3

State of Purpose ~ page 4

Hypothesis ~ page 4

Materials ~page 4

Procedure ~ page 4

Research ~page 5

Observation and Results ~page 6

Continue Observation and Results~ page 7

Conclusion~ page 8

References~ page 9

Acknowledgements ~ I would like to thank Cheri Blevins, Zack’s mother, for allowing us to use her corn syrup, salt, sugar, and her freezer for this experiment. I also would like to thank Ms. Smith for giving me the knowledge to complete this experiment and follow the correct steps and procedure in doing so.

State of Purpose ~ if solutes such as salt, sugar, and corn syrup are added to water, will they have an effect on the expansion of the water as it freezes? And if so, how dramatically will each solute affect the expansion.

Hypothesis ~ if sugar water is frozen, it will expand slightly less than regular water. If salt water is frozen, it will expand even less than the sugar water. If corn syrup is frozen, it will expand a similar amount as the sugar water due to the high level of sugar in corn syrup.

Materials ~ 4 paper cups, 105 ml of water, 5 ml of salt, 5 ml of sugar, 5 ml of corn syrup, and the freezer.

Procedure ~ first you add 25 ml of water to each cup and 5 ml to each solute to each cup. Mix the solutes and water until they are dissolved. Once they are dissolved, each cup should contain 30 ml of liquid. Put the cups in the freezer overnight. Once they are frozen, remove the cups and measure the expansion of the liquids as they froze and record the data on the table.

Research ~ -salt water will need to freeze at a lower temperature than fresh water (the control). The more salt in the solution, the lower the temperature will need to be for it to freeze.

-Adding a solute to a solution decreases the freezing point because it will interfere with the frozen solution's crystal structure.

- According to Raoul’s law, adding solute to a solvent will dilute the solvent molecules and this leads to a decrease in vapor pressure.

-most substances contract when frozen; however, water is an exception

- When a substance freezes, the molecules slow down and settle into a rigid regular pattern. Most solutes will make this a more difficult process which requires a lower temperature

Observations and Results ~

Effects of Solutes on Expansion of Frozen Water:

Solute ML Before Freezing ML After Freezing

None(Water) 30 34

Sugar 30 32

Salt 30 28

Corn Syrup 30 32

Water: Expanded more than the other solutes (as expected).

Sugar: Expanded slightly less likely due to the increase in density.

Salt: Solution did not freeze. Salt settled to the bottom and froze separately while the water remained liquid.

Corn Syrup: Expanded slightly less likely due to the increase in density.

Continue Observations and Results:

(Corn Syrup, Water, Salt, and Sugar before Freezing)

(Corn Syrup, Water, Salt, and Sugar after freezing)

Conclusion ~ To conclude our project, the hypothesis for our experiment was correct for all the solutes and everything else involved with our experiment. The salt did not freeze at all and the corn syrup and the sugar stayed the same. The salt fell to the bottom of the cup which lowered the water level. The expansion varied in the different solutes and everything worked out perfectly!

Reference page:

“Freezing” n.d. https://www.chem.purdue.edu/gchelp/liquids/freeze.html 1 Nov 2016

“Freezing Point Depression” Boundless, 8 Aug, 2016. https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/solutions-12/colligative-properties-of-nonelectrolyte-solutions-95/freezing-point-depression-407-4701/ 1 Nov 2016

“Freezing Saltwater” adam and mike W., 5 March, 2012. https://van.physics.illinois.edu/qa/listing.php?id=1598 1 Nov, 2016

“How Solutes Effect the Freezing and Boiling Points of a Solvent” Evans, 13 Feb, 2011. https://chemistry4gcms2011.wikispaces.com/How+solutes+affect+the+freezing+and+boiling+point+of+a+solvent+(Evans) 1 Nov, 2016

“Water Expansion on Freezing” n.d. https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/solutions-12/colligative-properties-of-nonelectrolyte-solutions-95/freezing-point-depression-407-4701/ 1 Nov, 2016