Lab: Reaction Rate

Pre-lab Questions

1. Name five factors that can affect the rate of a reaction.

3. In the opening paragraph example, it took more time to make sweet tea with cold water and sugar cubes than to sweeten hot tea with granular sugar. Why?

4. What is the primary factor that determines whether a reaction rate increases or decreases?

Procedure

1. Label four test tubes 1, 2, 4, and 5 (Reaction 3 takes place in the 50mL beaker, which is why you number the test tubes this way).

2. Break off a piece of CaCO3 rock with a mass of approximately 0.2 grams. Record the actual mass in the Data section. Place the rock in test tube 1.

3. Weigh out three more pieces of approximately 0.2 grams of CaCO3 rock. These should be as close as possi- ble to the mass of the first rock sample. Place the pieces of rock into test tubes 2, 4 and 5. Record each of their masses Table 1.

4. Into a 50 mL beaker, weigh out approximately 0.2 grams of CaCO3 powder. This should be as close as possi- ble to the amount of the previously weighed pieces of marble rock. Record the mass in Table 1.

Reaction # 1

5. Measure 10 mL of saturated citric acid solution into a 10 mL graduated cylinder. Transfer the acid to test tube 1 (with the CaCO3 rock), and place this test tube immediately in an ice bath. Record the start time. Check on this reaction frequently and record when the reaction no longer produces bubbles (gas). Record all values in Table 1, along with your observations.

Reaction # 2

6. Measure 5 mL of saturated citric acid solution (60%) into a 10 mL graduated cylinder and dilute to 30% by adding 5 mL distilled water. Transfer the diluted acid to test tube 2, and place this test tube in the rack. Re- cord the start time. Check on this reaction frequently and record the time when the reaction no longer pro- duces bubbles (gas). Record all values in Table 1, along with your observations.

Reaction # 3

7. Measure 5 mL of saturated citric acid solution (60%) into a 10 mL graduated cylinder and dilute it to 30% by adding 5 mL distilled water. Transfer this diluted acid to the 50 mL beaker that contains CaCO3 powder. Use a stopwatch to time the reaction from when the acid is poured onto the powder and until the reaction no longer produces bubbles (gas). Record all values in Table 1, along with your observations.

Reaction # 4

8. Measure 10 mL of saturated citric acid solution into a 10 mL graduated cylinder. Transfer the acid to test tube 4 and place this test tube in the rack. Record the starting time. Check on the reaction frequently and record the time when the reaction is no longer fizzing. Record all values in Table 1, along with your observa- tions.

Reaction # 5

9. Measure 10 mL of saturated citric acid solution into a 10 mL graduated cylinder. Transfer the acid to test tube 5, and place this test tube in the previously started hot water bath. Record the starting time. Check on this reaction frequently and record the time when the reaction stops (no longer fizzing). Record all values in Data Table 1: Reaction rate data and observations.

Calculations

Calculate the rate (g/sec) of each of the reactions you observed.

Post-lab Questions

1. All the reactions that you performed were chemically the same. You just varied several factors. What were the factors that were varied?

2. Which factor do you think made the biggest influence on the reactions? Why?

3. Out of the five different reactions, which reaction was the slowest? Was this what you expected? Why?

4. Why do you think marble statues require long periods of time to degrade inregions that are affected by acid rain?

Attachment:- Lab_Reaction_Rate.pdf