2:16 C YUMPU Collect and analyze data The girls conducted a carefully controlled experiment and found that after 3 hours and 15 minutes, the hot water had frozen solid, while the trays filled with cold water still contained a mixture of ice and water. They repeated the experiment two more times. Each time the hot water froze first. The second time they found that the the hot water froze in 3 hours and 30 minutes. The third time, the hot water froze in 3 hours and 0 minutes. 6. What is the average time that it took for hot water in ice cube trays to freeze? 7. Why is it a good idea to repeat your experiments? Make a tentative conclusion 8. Which of the following statements is a valid conclusion to this experiment? Explain your reasoning for choosing a certain statement. a. Hot water molecules don't move faster than cold water molecules. b. Hot water often contains more dissolved minerals than cold water, so dissolved minerals must help water freeze faster. C. Cold water can hold more dissolved oxygen than hot water, so dissolved oxygen must slow down the rate at which water freezes. d. The temperature of water affects the rate at which it freezes. e. The faster the water molecules are moving, the faster they can arrange themselves into the nice, neat patterns that are found in solid ice cubes. Test your conclusion or refine your question Maria and Elena are pleased with their experiment. They ask their teacher if they can share their findings with their science class. The teacher says that they can present their findings as long as they are sure their conclusion is correct. The last step of the scientific method is important. At the end of any set of experiments and before you present your findings; you want to make sure that you are confident about your work. 9. Let's say that there is a small chance that the results of the experiment that Maria and Elena performed were affected by the kind of freezer they used in the experiment. What could the girls do to make sure that their results were not affected by the kind of freezer they used? 10. Statement 8(b) suggests a possible reason why temperature affects the speed at which water freezes. Refine your original question for this experiment. In other words, create a question for an experiment that would prove or disprove statement 8(b). AA yumpu.com C