Bags of Reactions Chemistry I Acc

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1 Introduction: Bags of Reactions Chemistry I Acc Plop, plop, fizz, fizz, oh, what a relief it is. claims the old TV ad for a popular antacid. Just what is in the tablet that is relieving the upset stomach? What reaction is causing the fizzing? Can you write a balanced equation for this process? With a bit of investigating, you will be able to discover the answers to all these questions. As you learned early in the course, Antoine Lavoisier, in the eighteenth century formulated the law of conservation of mass. which states that matter can not be created or destroyed during a chemical process. During a chemical reaction, the bonds or the reactants are broken and rearranged to form new substances. Because matter must be conserved, these new substances, or products must contain the same number and types of atoms as the reactants. In this investigation, you will first verify the law of conservation of matter. Then in the second part, you will be given some known compounds to react. You will write and balance a chemical equation for the reaction. Procedure (part a): 1. Measure 25.0 ml of tap water with a graduated cylinder. Pour water into a resealable bag. Flatten air out of bag and measure the mass of the bag and water. Record the data in the data table (Remember the estimated digit). 2. Obtain 1/2 antacid tablet. Measure mass. Record in data table. 3. Tip the bag on a diagonal as pictured in figure 1 so that all of the water runs into one corner of the bag. Add the tablet to the bag such that the water and the tablet do not mix as shown in figure to the right. Seal bag while trapping as little air as possible. 4. Feel the temperature of the water before the reaction. Let the tablet drop into the water. Observe the reaction until it comes to a complete stop. Check the temperature of the water by feel after the reaction is complete. Record your observations in the data table. 5. When the reaction is complete, measure the mass of the bag and the products. Record in data table #1. Procedure (part b): 6. In a dry plastic resealable bag, add two scoops of calcium chloride (the exact amount is not important). 7. Add one scoop of sodium hydrogen carbonate (Sodium bicarbonate) to the bag and shake gently to mix. 8. Determine the mass of the bag and the chemicals. Record the result in data table #2.

2 9. Measure 25.0 ml of tap water into a graduated cylinder. Add 10 drops of phenol red ph indicator to the water. 10. Tip the bag on the diagonal and shake the chemicals into one corner. The pinch off the solids from the rest of the bag and add the water to the bag such that the chemicals do not mix. Keeping the trapped air to a minimum, reseal the bag. 11. Feel the temperature of the water and then mix the dry chemical with the water. Observe the reaction until it reaches completion. Check the temperature of the bag by feel. Record your observations in data table # Measure the mass of the unopened bag. Record in data table #2. Clean up your work area and wash your hands before leaving the laboratory.

3 Chem I Acc Name Bags of Reactions Report Sheet Pre-Lab Read the entire laboratory assignment and the relevant pages in your textbook. Answer all pre-lab question before beginning the lab. 1. Define reactants. 2. Define products. 3. What are the four signs of a chemical reaction? 4. What is the point of using a resealable bag in this experiment? 5. What is the density of water? Why do you need to know that in this lab? 6. What is the common name for sodium hydrogen carbonate? Data and Observations Data Table 1 mass of bag and water Write observations of reaction here mass of half-tablet mass of bag and products

4 Data Table 2 mass of bag and dry reactants Write observations of reaction here volume of water mass of bag and products Calculations 1. Calculate the total mass of the bag and reactants in the reaction in part a by adding the mass of the bag and water to the mass of the half-tablet. 2. Using the formula for the density of water, calculate the mass of the water in part b. 3. Calculate the total mass of the bag and reactants in the reaction in part b by adding the mass of the bag and dry reactants to the mass of the water from calculation #2. Analysis and Synthesis 1. How do the values for the total mass of the bag and reactants compare to the total mass of the bag and products in each reaction? 2. What were five observations you made in part A that indicated a reaction had occurred? Hint: There is more than one way to detect that a gas has been produced. 3. Write a balanced equation in words and then with formulas for the reaction that occurred in part b. The products are sodium chloride, calcium hydroxide and carbonic acid. Hint: Water is a reactant.

5 4. Was there a ph change in reaction b? What is the evidence to support this conclusion? 5. If your answer to question number 4 was yes, did the bag become more acidic or basic. What is the evidence to support your answer? 6. Carbonic acid immediately decomposes into water and carbon dioxide. Write the balanced chemical equation for this decomposition reaction. 7. What gas was produced in part a? Hint: Sodium hydrogen carbonate is an active ingredient in the antacid. 8. Predict the products and balance the reaction for the double replacement reaction between acetic acid and baking soda. 9. Predict the products and balance the reaction for the decomposition reaction of hydrogen peroxide when catalyzed by manganese dioxide.