Scenario+2+pd+7

Al's Salt Water Experiment

Al wonders if adding salt to water will affect how long it takes the water to freeze. Al __thinks that salt water will freeze more quickly than fresh water__. He decides to check his hypothesis by conducting an experiment. __Al takes two ice trays and fills one with distilled water and the other with distilled water that has two tablespoons of salt added__. He makes sure he puts exactly the same amount of water in each ice tray. Al takes the trays and puts them side by side in the freezer. Al checks the ice trays every 10 minutes to see if the water in each tray has begun to freeze. __Al finds that after 20 minutes the water in the ice tray without the salt has started to form ice while the ice tray with the salt water is completely liquid.__

Complete each of the following:
 * 1) Identify Al's hypothesis: Al's hypothesis is that salt water ice trays will freeze faster than fresh water ice trays when put in the freezer.
 * 2) Identify the independent variable :The independent variable is the ice tray with salt that is being put in the freezer.
 * 3) Identify the dependent variable: The dependent variable is both the ice trays in the freezer.
 * 4) Identify the other variables Al needs to consider/control during this experiment: The icetrays need to be kept at the temperature, they need to be the same size ice trays, they need to be put in the same freezer, they need to be put right next to each other, the water in both trays needs to be clean, the trays need to be in good conditon, the amount of water put in the trays needs to be the same amount, and you have to keep using the same kind of salt.
 * 5) Identify the control group in this experiment: The control group is the ice tray with fresh water in it.
 * 6) Identify the experimental group: The experimental group would be the ice trays with salt water.
 * 7) What conclusions might Al draw from this data? Al's conclusion might be that fresh water freezes faster than salt water.
 * 8) What recommendations might you suggest for further study or for improvement? Al can try using less salt in the water, or more salt in the water to see if that will help the water freeze faster.