My STEM Fair Project Mr. Thornton

Question

Does the temperature of water affect how long salt dissolves?

Purpose

I wanted to do this project because we were learning about mixtures and solutions in science class and I always wondered what makes salt dissolve faster.

Hypothesis

I think the warmer the temperature of the water it will dissolve salt faster because I know that hotter temperatures have particles moving faster and maybe they’ll break up the salt faster.

Materials

•3 clear plastic cups •salt •teaspoon (for measuring) •teaspoon (for stirring) •hot, room temperature, and cold water •graduated cylinder •stop watch •markers to label cups

Variables

Independent: Temperature of the water Dependent: Amount of time for salt to dissolve (in seconds) Control: size of cups, amount of water, amount of salt, stirring speed

Step-by-step Directions

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Label 3 cups: Hot, Room Temp., Cold Pour 100 mL of hot water in the cup Measure a level teaspoon of salt Dump the salt in the hot water cup and start the timer Stir the salt repeatedly until the salt is dissolved Record the time it took to dissolve the salt Repeat steps 2-6 two more times.

Repeat steps 2-6 three times with Room Temperature water Repeat steps 2-6 three times with Cold water

Trial Data

Average Data

Conclusion

According to my data, my hypothesis was correct. Warmer temperatures do make salt dissolve faster in water. The average time it took to dissolve salt in hot water was 22.6 seconds, which was faster than room temperature’s average time, 43.3 seconds and way faster than cold temperature’s 78.6 seconds. I think this is good to know especially for cooks who have to dissolve salt or sugar when they cook. One way to improve this experiment would be to be more careful I was stirring the same speed because I am not sure if I was stirring with the same speed or not. If I did this experiment again, I would try it with sugar and see if I got the same kind of results. I also wonder if the same thing would happen if I used a different liquid like vinegar.