Koby wanted to do an experiment where he could observe a chemical reaction. He decided that he was going to combine baking soda with water and with vinegar and see whether either one created a chemical reaction. Koby placed ½ teaspoon of baking soda into each of two identical glasses. He noticed the baking soda was lumpy, so he used a fork to break up the lumps. Why is it important to break up the lumps? Part B He added ¼ cup of room-temperature water to one glass and ¼ cup of room-temperature vinegar to the other. Before you see Koby's results, make a hypothesis about each combination. Will combining water and baking soda result in a chemical reaction? Will combining vinegar and baking soda result in a chemical reaction? Part C The videos show what happened when Koby added the liquids to the baking soda. Water Vinegar Koby noted that the glass with the water was room temperature but the glass with the vinegar felt colder. Examine the videos, and record your observations about Koby's results. Analyze and Extend Part A Explain whether a chemical reaction occurred for each combination. Include the evidence you used to reach your conclusion. Part B Is this investigation a controlled experiment or an observational study? Explain your answer. Part C Why did Koby use the same amount of baking soda and same amount of liquid for each combination?