Types of Chemical Reactions
Pre-Lab
Answer the following questions:
1. What are the 5 indications that a chemical reaction has taken place?
2. Define the 7 different types of chemical reactions.
3. State in which steps in this lab you would use a bunsen burner.
4. How many times is acid used in this lab?
5. What do you do with all of the reagents in this lab?
6. What is the hottest part of the bunsen burner flame?
Objectives
1. to observe a variety of chemical reactions.
2. to interpret and explain observations with balanced chemical equations.
3. to classify each reaction as one of the seven main types.
Caution!!!
Most of the solutions that you will be using in this lab are poisonous, corrosive, or irritants. When handling these solutions wear your goggles, laboratory apron and plastic gloves. Wash any spills and splashes immediately with plenty of water and call your teacher.
Materials
Apparatus
bunsen burner 6 test tubes test tube clamp medicine dropper
wood splints crucible tongs steel wool safety goggles
lab aprons
Reagents
copper wire (bare) iron nail
0.5M copper(II)sulphate solution copper(II)sulphate pentahydrate
water 0.5M calcium chloride solution
0.5M sodium carbonate solution mossy zinc
2M hydrochloric acid solution hydrogen peroxide solution(6%)
manganese(IV)oxide
Reagent Disposal
Place all liquid and solid wastes into the designated containers.
Table 1-Observations for Types of Chemical Reactions
Observations
Reaction Before During After
1
2
3
4
5
6
7
Procedure
1. Put on your safety goggles and lab apron.
2. Make observations before, during, and after each reaction. Record your observations in your copy of Table 1.
3. Each different reaction is at a different station throughout the room. Travel throughout the room so that all of the 7 reactions are completed in your table.
Reaction 1
4. Adjust a burner flame to high heat.
5. Using crucible tongs, hold 6 cm length of bare copper wire in the hottest part of the flame.(The hottest part of the flame is the top of the blue cone.) for a few minutes.
Reaction 2
CAUTION: Copper(II)sulphate is poisonous. Do not get any in your mouth; wash any spills or splashes away with plenty of water.
6. Clean an iron nail with a piece of steel wool so that the surface of the nail is shiny.
7. Place the nail in the test tube and add copper(II)sulphate solution so that one half of the nail is covered.
8. After approximately 15 minutes, remove the nail and note any changes in both the nail and the solution. You should move on to Reaction 3 and 4 while you are waiting for Reaction 2 to finish.
Reaction 3
9. Put some solid copper(II)sulphate pentahydrate in a test tube so that it is one third full.
10. Using a test tube clamp, hold the test tube and contents at an angle away from yourself and your classmates. Heat the test tube, moving it back and forth gently over the bunsen burner flame.
11. Continue heating until no further change is observed.
12. Save the contents for Reaction 4.
Reaction 4
13. Allow the test tube from reaction 3 to cool for 5 - 10 minutes.
14. Use a medicine dropper to add 2 or 3 drops of water to the test tube.
15. Go back and make your observations of Reaction 2.
Reaction 5
16. Fill a test tube one quarter full with calcium chloride solution. Fill a second test tube one quarter full with sodium carbonate solution.
17. Pour the calcium chloride solution into the test tube containing the sodium carbonate solution.
Reaction 6
CAUTION: Hydrochloric acid is corrosive to skin, eyes, and clothing. When handling hydrochloric acid, wear safety goggles, lab apron, and gloves. Wash spills and splashes off your skin and clothing immediately using plenty of water and call your teacher.
18. Place a piece of mossy zinc in a test tube.
19. Add hydrochloric acid solution to the test tube until the mossy zinc is completely covered.
Reaction 7
20. Half fill a test tube with hydrogen peroxide solution.
21. Add a small amount of manganese(IV)oxide. (NOTE: Manganese(IV)oxide acts as a catalyst in this reaction.)
22. Test the gas evolved by placing a glowing (not a burning) splint into the mouth of the test tube.
NOTE: Before you leave the laboratory, wash your hands thoroughly with soap and water; use a fingernail brush to clean under your nails.
Post Lab Discussion
1. To predict the products of a reaction, it is often helpful to examine the chemical formulas of the reactants. Therefore, your first task is to determine which chemicals reacted in each case, then write chemical formulas for these reactants.
2. Next, using a combination of logic and your observations located in table 1, predict the products for each reaction.
3. Finally, balance each equation so that the number of atoms is conserved.
4. Classifying the reactions requires you to match each equation with one of the seven types.
Questions
1. In Reaction 1, with which substance in the air did the copper react?
2. In Reaction 2, changes occurred in both the nail and the solution. What do the changes in the solution indicate?
3. What evidence did you see that chemical reactions took place in Reactions 3 and 4?
4. In Reaction 5, one of the products is sodium chloride (table salt), which, as you know, is highly soluble in water. What, therefore, would be the product that would account for the precipitate which formed?
5. How could you test the gas released in Reaction 6 to confirm its identity?
6. a) What does the glowing splint test suggest about the identity of the gas evolved in Reaction 7?
b) The formula for hydrogen peroxide is H2O2. Two products are formed in Reaction 7, one of with a common gas which you know from Question 6. a., and the other a common liquid. What is the most likely identity of this common liquid?
Conclusion
Using proper sentence form for each of the seven reactions in this experiment, write a balanced equation and classify the type of reaction.