Question

Stacy reads that a 50:50 mixture of methanol and water is best for keeping a car’s radiator from freezing when the temperature goes down to –40°C. Design an experiment to test this finding. You have a –40°C freezer, water, methanol, graduated cylinders to measure volume, several plastic beakers, and a watch at your disposal. Be sure to state your hypothesis, procedure, and any controls in your experiment. What are the dependent and independent variables? Explain the possible results if your hypothesis is true.

Answer 1

1. The hypothesis for this is experiment is that the 50:50 of methanol-water mixture will not turn to solid when the temperature reaches to -40°C.

2. The procedure for this is measuring equal volumes of water and methanol using the graduated cylinder. You can measure 100 mL of water and 100 mL of methanol using the graduated cylinder. Then, mix them in the beaker. Next, measure 200 mL of water, and another 200 mL of methanol. Don't mix them. Also, make a 60:40 mixture by measuring 120 mL of water and 80 mL of methanol, then mix them together. Place them all in the refrigerator at the same time. Record the time when they would freeze to solid.

3. The controls for this experiment are the 200 mL water alone, and the 200 mL methanol alone.

4. The independent variable in here is the time, while the dependent variable is the temperature of the mixtures.

5. If the hypothesis turns out to be true, then all the mixtures prepared should freeze and become solid after a certain period of time, with the exception of the 50:50 mixture. The 50:50 mixture should still remain as a liquid even when left overnight.

Answer 2

Hypothesis: If a mixture of methanol and water is made with an equal amount of water and methanol, more water than methanol, and less water than methanol, then the mixture with less water than methanol will be the best at resisting freezing when in temperatures of -40 degrees Celsius. You have to first measure equal amounts of methanol and water in graduated cylinders then pour into plastic beaker. For a second trial measure two parts water and one part methanol then pour them in separate beaker.