Evidence for Chemical Reactions

Problem:

What evidence shows that a chemical reaction has occurred?

Materials:

3 test tubes test tube rack iron nail white vinegar calcium carbonate barium chloride solution potassium sulfate solution lead (II) nitrate solution potassium iodide solution copper (II) sulfate solution

Procedure:

1. On your table you will find the following chemicals: Barium chloride Iron nail Potassium sulfate, Calcium carbonate chip Lead (II) nitrate Copper (II) sulfate Potassium iodide Vinegar

2. In the chart provided, write the formula of each substance under its name

3. Observe the appearance of each solution and record your observations in your data table.

4. Using the droppers provided, add a dropper-full of potassium sulfate to a clean test tube. Add barium chloride solution drop by drop and make your observations and record them in your data table.

5. Add a dropper-full of potassium iodide solution to a new test tube. Add lead nitrate solution drop by drop. Make observations and record in your data table. 7. Add a dropper-full of copper sulfate solution to a clean test tube. Place the iron nail into the test tube. Observe what happens over the next 10 mins. Record your observations in your data table.

8. Add a dropper-full of vinegar to a clean test tube. Add the calcium carbonate chip to the test tube. Make your observations and record in the data table.

Observations: Table 1

Substances and their formulas Observations

Barium chloride

Potassium sulfate

Lead (II) nitrate

Potassium iodide

Copper (II) sulfate

Vinegar (Acetic acid)

Iron nail

Calcium carbonate chip Table II Reactants Observations

Potassium sulfate + Barium chloride

Potassium iodide + Lead nitrate

Iron + Copper (II) sulfate (Note: Iron will form Iron (III) ions)

Calcium carbonate + Acetic acid (Note: acetic acid is HC2H3O2) Analysis

1. Each of the changes you observed involved a chemical change. What evidence showed that a chemical reaction took place when you combined the barium chloride solution with the potassium sulfate solution?

2. What evidence showed that a chemical reaction occurred when you combined the lead nitrate solution and potassium iodide solution?

3. What evidence showed that a reaction occurred when you placed the iron nail into the copper sulfate solution?

4. What evidence showed that a reaction occurred when you added the calcium carbonate to the acetic acid solution?

Conclusion

1. Write a paragraph about the kinds of changes that you would expect to see whenever a chemical reaction occurs

2. Any one of these signs is not always a foolproof indication that a chemical reaction is occurring. Give two examples to support this statement.

3. Write the balanced chemical equation for each of the reactions that took place during this lab.

4. Name the type of reaction for each of the reactions that took place during this lab.