Science Project Details:

The effect of salt and sugar on the freezing point of water

Featured science projectScience project video Intermediate 6 < 1 day $10-$25 Readily available [+] More info
Difficulty: Intermediate 6
Cost ($): 10
Time required: < 1 day
1 day for preparation, 5 hours for experiment
Availability of materials: Readily available
Easily found
Required Skills: None
Safety concerns:

None

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Abstract

This science fair project was done to find out how the freezing point of water is affected by the presence of sugar or salt. The experiment was conducted using salt, sugar and water.

Hypothesis

The freezing point of water will be lowered when sugar or salt is added.

Scientific Terms

Molar mass, mol, freezing point depression

Background

Molar mass

The mass of 1 mole of an element (Molar mass) refers to 6.0221415 x 1023 atoms or molecules of the element. Although the SI unit of mass is in kilograms, molar mass is almost always mentioned in grams per mole. Salt has a molar mass of 5.8g per mol, while sugar has 34g per mol.

Freezing Point Depression

The term "freezing point depression" refers to a condition where the freezing point of a liquid is lowered by the presence of an additive. This is observed in all solutions, and the freezing point is determined by the amount of solute particles dissolved in the solvent.
At the freezing point of that particular solution, the chemical potential of the solution at liquid state and solid state will be equal. Solute particles are able to dissolve only in a liquid solvent. Conversely, when the solvent is in a solid state, solute particles cannot be dissolved. Following the same logic, adding a solute to the solvent will reduce the chemical potential of the solution and consequently, also its freezing point.