The Effect of Dissolved Salt and Sugar on the Melting Rate of Ice

Researched by Michelle C
2003-04



PURPOSE

The purpose of this experiment was to determine the effect of dissolved salt and sugar on the melting rate of ice.

I became interested in this idea when my brother froze salt and water. The results made me wonder if other substances would have the same results.

The information gained from this experiment would help those in the food industry know how salt and sugar content would affect frozen foods.


HYPOTHESIS

My first hypothesis was that pure water would melt slower than water with impurities.

My second hypothesis was that the more impurities in the water the faster it would melt.

I based my hypotheses on The World Book Encyclopedia that states, “Water which contains impurities freezes at lower temperatures than pure water.”


EXPERIMENT DESIGN

The constants in this study were:
* Amount of liquid in each ice “cube”
* Time in freezer
* Shape of ice cubes
* Size of cups
* Kind of cup
* Room temperature for melting

The manipulated variable was the amount of solute dissolved in the water.

The responding variable was the amount of time it took for the ice to melt. 

To measure the responding variable I determined the time in minutes it took for them to melt in minutes.


MATERIALS


QUANTITY ITEM DESCRIPTION
45 100 ml plastic cups
111 Grams of salt
111 Grams of sugar
2,889 ml of Distilled water
1 Freezer
1 Room (room temperature)
1 Funnel
1 stopwatch
1 data table
3 100 ml graduated cylinders
3 funnels


PROCEDURES

1. Create three concentrations of salt solution:
a. Measure 100 g. of table salt on a triple beam balance.
b. Measure 900 ml. of distilled water using a graduated cylinder
c. Pour salt into the distilled water and stir until dissolved.
d. Label this as “10% salt”
e. Repeat steps 1a ? 1d except use 10 g. of salt and 990 ml.-distilled water. Label as “1% salt”
f. Repeat steps 1a ? 1d except use 1 g. of salt and 999 ml.-distilled water. Label as “0.1% salt”
2. Create three concentrations of sugar solution 
a. Repeat all of step 1 except use granulated sugar instead of salt
b. Label each with the word “sugar” instead of “salt.”
3. Make pure water ice cubes
a. Pour 100 ml. of distilled water into a small paper cup.
b. Label “Control #1”
c. Repeat 3a -3b four more times except number the cups appropriately: Control #2 ? Control #5
4. Make salt solution ice cubes
a. Pour 100 ml. of 10% salt solution into a small paper cup.
b. Label “Salt 10% #1”
c. Repeat 4a - 4b four more times except number the cups appropriately: “Salt 10% #2”, etc.
d. Repeat 4a - 4c using 1% salt solution and labeling appropriately “Salt 1% #1”, etc.
e. Repeat 4a - 4c using 0.1% salt solution and labeling appropriately “Salt 0.1% #1”, etc.
5. Make sugar solution ice cubes by following steps 4a ? 4e except
a. Use the correct sugar solutions
b. Label all with the word “Sugar” instead of “Salt”
6. Freeze all cups for at least 24 hours.
7. Conduct melting test with pure water ice cubes.
a. Put a funnel into a 100 ml graduated cylinder.
b. Repeat 7a four more times.
c. Take all 5 of the pure water ice cups out of the freezer and set out in room temperature.
d. Invert each cup into a separate funnel.
e. Start the electronic timer.
f. Every 15 minutes measure the volume of melted liquid in each of the graduated cylinders
g. Record time and volume in data table for each cup.
h. Repeat steps 7f ? 7g until all 5 cups of ice melt totally.
8. Conduct melting test with salt solution ice cubes
a. Repeat 7a-7h with the 10% salt solution ice
b. Repeat 7a-7h with the 1% salt solution ice
c. Repeat 7a-7h with the 0.1% salt solution ice
9. Repeat melting test with sugar solution ice cubes by repeating step 8 except using the 3 concentrations of sugar solution.
10. Average the results for each group.


RESULTS

The original purpose of this experiment was to determine the effect of dissolved salt and sugar on the melting rate of ice.

The results of the experiment were that pure water melted the slowest with an average of 401 minutes. The 0.1% sugar ice cubes melted in 365minutes, the 1% sugar in 339 minutes, and the 10% sugar in 189minutes. The 0.1% salt ice cubes with melted in 341 minutes, the 1% in 373minutes and the 10% in 228.4 minutes. So the sugar ice cubes did melt faster than salt ice cubes, except with 0.1% impurities in them.

See the table and graphs below.


CONCLUSION

My first hypothesis was that pure water would melt slower than water with impurities.
 My second hypothesis was that the more impurities in the water the faster it would melt.

The results indicate that my first hypothesis should be accepted, because the pure water ice cubes  melted slower than water with impurities, the pure water melted in an average of 402 minutes, but with impurities they melted around 350 minutes. My second hypothesis should also be accepted because the more impurities in the ice cubes the faster they melted, the 10% average sugar was 189 minutes, and the water was 402 minutes.

Because of the results of this experiment, I wonder if the ice cubes, melting rate would be affected if I put them in a warmer or colder room during melting

If I were to conduct this project again I would use hot water instead of cold water to dissolve the impurities completely, use more concentrations like, 10%, 5%, 2.5%, 1.25%, .625%.



RESEARCH REPORT
Introduction

Water is a liquid that freezes and also melts at 32*F (0*C). Melting and freezing points are temperatures when a solid substance turns to a liquid. Liquid is a substance that is called a fluid because it flows to fit its container.

Water
Water is a liquid that is odorless, colorless, and tasteless. Water freezes and melts at 32*F (0*C). As water freezes it expands by one-eleventh. The amount of pressure on the water when it is freezing changes the melting point. Water that reaches 40*F it is at its maximum density. The molecules in water are always rapidly moving, until it gets cold and then they start slowing down. Water can be in three different forms: liquid, gas, and solid.

Ice
Ice is a solid form of water. At 4*C, (39*F) water contracts and at 0*C it freezes. Ice has molecules that as it freezes move more slowly, due to them moving apart. When it freezes it expands by one-eleventh and then the ice becomes lighter than water, so it is able to float. Ice is colorless, transparent, and has hexagon crystals. When the ice is in a warm environment the ice melts layer by layer.

 Sugar
Sugar is most commonly use as a sweetener. It mostly comes from sugar cane
 and sugar beat, and is in the class of carbohydrates. Sugar cane are tall stalks and are about 7-15 feet high. The sugar is in the stalks and the starch in them is broken down into sugar. The sugar is made by crushing the stalks and squeezing out the sugar. Sugar is mostly grown in warm temperature. There are two kinds of sugar, Monosaccharide, and disaccharides. When they are pure they are white crystals. Monosaccharide is the simplest carbohydrate and includes glucose and fructose Disaccharides includes lactose and maltose but the most important one is sucrose.

Salt
Salt is normally used to flavor and store foods. Its chemical name is sodium chloride and it comes from underground deposits. Salt and ice mixed together lower the melting point, so 20% of all U.S. salt is used to melt snow or ice off of roads. The United States uses 5% of salt on food, in restaurants and in stores. There are many kinds of salt and rock salt is one of them. Rock salt is found in hard layers underground. It was made by evaporation of large amounts of ancient ocean water, it is also found in every continent. The salt is found in formations called salt domes, and is lighter than other minerals. The salt domes are formed when rock salt flows through overlying rocks; water then dissolves the salt to make brine. Another kind of salt is table salt. Table salt tends to clump together at high humidity. Salt is odorless, colorless, and generally harmless.

Thermodynamics
Thermodynamics is the study of different forms of energy, such as heat and work. Thermodynamics is made up of two main laws. The first law of thermodynamics explains conservation of energy. In a closed system energy cannot be created or destroyed, but it can be converted from one form to another. For example, chemical energy in fuel can be change to heat energy by a flame. The total amount of energy is always the same. 

The second law of thermodynamics says that heat will flow from a hotter item or substance to a less warm thing. An example would be melting ice.  Heat energy from the air flows into the outer surfaces of the ice, causing those molecules to move faster.  If the molecules move fast enough, they change from the solid ice stage to the higher energy liquid stage. We say that the ice is melting.

Melting Point
Melting point is the temperature when a solid turns to liquid. The melting point is based on if the liquid is pure or a mixture. Pure substances melt at the same temperature it freezes. Melting points are determined by pure and mixture substances. Different crystals will melt at different temperatures. 

Freezing Point
The freezing point is the temperature at which a liquid turns to solid. The freezing point is different in liquids. Freezing point depends on the pressure against it. The freezing point can be the same if the amount of liquid and solid are the same.

Summary
Water is a very important thing to people and the world. It helps many people and is very interesting for people to study, 

BIBLIOGRAPHY

Boehm, Robert F. “Thermodynamics” The World Book Encyclopedia 1998.

Chesick, John P. “Freezing Point” The World Book Encyclopedia 1998.

Chesick, John P. “Melting Point” The World Book Encyclopedia 1998.

Dean, Walter E. Jr. “Salt” The World Book Encyclopedia 1998.

Hartman, Robert F. “ Ice” The World book Encyclopedia 1998.

Martin, Richard A. “Liquid” The World Book Encyclopedia 1998.

Price, Jack and Heimler, Charles H. Physical Science. Mirril Publishing Company

“Water” Columbia Encyclopedia. Encyclopedia.com, November 20.2003. 
http://www.encyclopedia.com/htm/w1/water.asp

Wyse, Roger E. “ Sugar” The World Book Encyclopedia 1998.

 

ACKNOWLEDGEMENTS

I would like to thank the following people for helping make my project possible:
* My parents for buying my supplies and supporting me.
* I would also like to thank Mr.Newkirk and and Mrs.Helms for all of their endless hard work.
* I would also like to thank Mr. Arambul for allowing me to use his supplies.


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