Question

LAB Reaction Rates

Objectives

• Evaluate the effect of concentration on the rate of a chemical reaction. ν

• Examine the effect of temperature on the rate of a chemical reaction.

Background: Many people believe that you cannot perform chemical reactions without expensive equipment or costly chemicals. But this isn’t true; chemical reactions happen everywhere. All you need is a food store to find many substances that can produce exciting chemical reactions.

Preparation

Materials

water	vinegar solution
baking soda	balloons (3)
plastic 0.5-liter	test tube
soft-drink bottles (3)	150-mL beakers (2)
marker	500-mL beaker
stopwatch, or clock	100-mL graduated
with second hand	cylinder
tape

Safety Precautions

Procedure

1. Read the procedure and safety information, and complete the lab form.

2. Make data tables similar to those shown on the next page.

3. Prepare a 50 percent vinegar solution by mixing 30 mL of vinegar with 30 mL of water. This is solution A.

4. Prepare a 30 percent vinegar solution by mixing 30 mL of vinegar with 70 mL of water. This is solution B.

5. Prepare a 10 percent vinegar solution by mixing 30 mL of vinegar with 270 mL of water. This is solution C.

6. Pour the vinegar solutions into their associated 0.5-L plastic bottles labeled A, B, and C.

7. Mark a small test tube about 1–2 cm from its bottom. Fill the test tube to the line with baking soda. Pour the baking soda into one balloon.

8. Repeat step 7 with two more balloons. Be sure the amount of baking soda in each balloon is the same.

9. Place the mouth of one balloon over the mouth of one 0.5-L bottle. Do not let any of baking soda fall into the vinegar solution.

10. Repeat step 9 with the other two balloons and the remaining bottles.

Inquiry Lab

11. Lift each balloon to allow the baking soda to fall into each vinegar solution. Time how long it takes for the reaction to finish. Measure how much each balloon inflates. Record your observations in your Concentration data table.

12. Carefully remove the balloons from the bottles.

13. Rinse the plastic bottles with water.

14. Prepare a 30 percent vinegar solution by mixing

30 mL of vinegar with 70 mL of cold water.

15. Prepare two more similar solutions with room-temperature water and hot water.

16. Place the three solutions in the three 0.5-L plastic bottles.
17. Repeat steps 7 and 8 to refill the balloons with baking soda.

18. Place the balloons back on the bottles, repeating steps 9 and 10.

19. Repeat step 11. Time how long it takes for the reaction to finish.

20. Measure how much each balloon inflates. Record your observations in your Temperature data table.

Concentration Data Table (Ballon circumferrence)

Vinegar Concentration	Solution A (50%)	Solution B (30%)	Solution C (10%)
Observations	8.5 cm	6.20cm	4.00cm

Temperature Data Table (Circumferrence of ballon)

Solution temperature	Cold Room Temperature	Room Temperature	Hot temperature
Observations	3.50 cm	5.00 cm	7.00 cm

Analyze Your Data

1. Describe how increasing the concentration of a solution affects the rate of a chemical reaction. (Concentration increases rate increases)

2. Summarize how temperature affects the rate of a chemical reaction.(Temperature increases rate increases)

3. Explain why the balloons become inflated.( Because of Co2)

Conclude and Apply

4. Infer why the vinegar solutions in steps 3, 4, and 5 were different volumes. Why couldn’t the volumes be the same?

5. Predict what factors might affect the amount of product that is produced. What factors affect the rate at which products are produced?

Answer 1

1. Overall reaction between vinegar(CH₃COOH) and baking soda (NaHCO₃)

CH₃COOH + NaHCO₃ = CH₃COONa + CO₂ (g) + H₂O (l)

rate of the above reaction would be r = K [CH₃COOH ] [NaHCO₃], where is K is the rate constant

from the above data table it is clear that with the increasing concentration of vinegar volume of CO₂ will be increased (it is clear from the circumference of ballon )

hence, it can be concluded from rate equation, with increasing the concentration of vinegar rate will also increase,

2. as it is well known from gas law volume is directly proportional to temperature.From the temperature data table it is clear that with increasing the temperature the volume of CO₂ increases and it will be possible when more number of vinegar and baking soda will react with each other. Therefore, with increseing temperature rate will increase.

3. Due to the production of gaseous CO₂ , during reaction between vinegar and baking soda all the balloons become inflated. The circumference of the balloon will increse with increase of volume of CO₂ or with increasing rate of the reation.

4. In step 3, 4 and 5 the strength of the vinegar solution is different but the volume of taken pure vinegar is same. therefore volume of all the vinegar solution were different. If all the volume were same, then the strength of all solution will be equal as a result we can't predict how the rate of a reaction is varied with concentration of the reactant.

5. Factors affect the produced product: Based on Le Chatelier's principle volume, pressure, temperature of the system might affect the amount of product.

Factors affect the rate : concentration of the reactants, temperature, physical state of the reactants, presence of the catalyst etc.