Factors and Reaction Rate

Scientific Title

The effect of various factors on the rate of reaction.

Problem Statement:

• What is the effect of factors on the rate of reaction?

Hypothesis:

• If factors are increased or decreased, then the rate of which a reaction occurs will increase or decrease because a chemical reaction depends on the frequency of the collision between atoms or molecules of the reactants.

Variables

– Independent variable– Dependent variable– Constant

The effect of temperature on reaction rate.

• Hypothesis:• Variables:– Independent– Dependent– Constant

Activity #1 - Materials

• 3 alka-seltzer tablets• 3 beakers• Cold water (50 mL)• Room temperature water (50 mL)• Hot water (50 mL)• Stop watch• thermometer

Activity #1 – Procedures:

• 1. Pour 50 mL of hot water in a 150 mL beaker.• 2. Pour 50 mL of room temperature water in a

150 mL beaker.• 3. Pour 50 mL of cold water in a 150 mL

beaker.• 4.Record the temperature of each.• 5.Place 1 tablet in each beaker and record

how fast the reactions took place.

Activity #1 – Data TableTrial # Reaction Time (seconds for

dissolving tablet)Temperature (degrees Celsius)

#1 0

#2 20

#3 60

Activity #1 - Analysis Questions:• 1. Draw a Water Temperature vs Reaction Time graph.• 2. The rate of the hot water was how many times faster than

at 0 degrees Celsius?• 3.Estimate the time it would take to dissolve an alka-seltzer

tablet at 10 degrees Celsius.• 4. What if the temperature is doubled from 20 degrees Celsius

to 40 degrees Celsius, by how much will the reaction rate change?

• 5. Explain temperature and the rate of reaction in terms of the collision theory. What is happening to the particles?

Activity #2-The effect of surface area on reaction rate.

• Hypothesis:• Variables:

-independent-dependent-constant

Activity #2 - Materials

• 3 alka-seltzer tablets (whole, 8 pieces, crushed)

• Mortar and pestle• Stop watch• 3 beakers • Water (150 mL)

Activity #2 – Procedures:

• 1. Place 50 mL of water in each of the three beakers.• 2.Break one tablet in 8 pieces.• 3. Use the mortar and pestle to crush one tablet. • 4. Place a whole tablet in one beaker and record the

reaction time.• 5. Place the 8 pieces of tablet in the second beaker

and record the reaction time.• 6. Place the crushed tablet in the third beaker and

record the reaction time.

Activity #2 – Data TableTrial # Reaction Time (seconds for

dissolving tablet)Tablet

#1 “Whole” tablet

#2 “8-piece” tablet

#3 “Crushed” tablet

Activity #2 – Analysis Questions:

• 1. What is the effect of particle size on the rate of the reaction?

• 2. The rate of the reaction for the crushed tablet was how many times faster than that of the whole tablet?

• 3. As the particle size decreases, what is the effect on the total surface area and the probability of interactions between atoms/ions rate of reaction?

• 4. Explain the surface area and reaction rate in terms of the collision theory.

Activity #3 – The effect of a low pH on reaction rate.

• Hypothesis:• Variables:– Independent variable– Dependent variable– Constant

Activity #3 – Materials

• Vinegar• Baking soda• Canister with lid• Stop watch• Graduated cylinder• Spoon

Activity #3 – Procedures:

• 1. As a group decide how much vinegar and baking soda that will be placed in the canister. Record the amount on the data table.

• 2.Place different amounts of vinegar and baking soda in the canister 3 different times.

• 3.Record the rate of reaction that occurs all three times on the data table.

Activity #3 – Data TableTrial # Reaction(seconds for

tablet to dissolve)pH of solution

#1 Neutral water pH=7

#2 Slightly acidic 5% by Vol. Acetic acid pH=3

#3 Strongly acidic 1.00 Molar HCl pH - 0

Activity #3 – Data Analysis:

• 1. Draw a Concentration vs Reaction Rate graph.

• 2. How does varying the amount of each substance affect the reaction rate?

• 3. Which concentration reacted the fastest? Why?

• 4. Explain the concentration and rate of reaction in terms of the collision theory.

Conclusion-Paragraph #1• The lab entitled The effect of factors on reaction rate, has to

do with how various factors such as temperature, surface area, and concentration can increase or decrease the reaction rate. There were three different procedures. The procedures for temperature, was to first measure 100 ml of hot water, cold water, and room temperature water in three 250 ml beakers. The second step was to use three alka-seltzer tablets and add one to the cold water, the second to hot water, and the third to the room temperature water. The third step was to time how long it took for the alka-seltzer to dissolve at the various temperatures and record the time.

Conclusion-Paragraph #1

• In the first activity, the various temperatures represented the independent variable, the reaction time represented the dependent variable, and the amount of water was the constant.

Conclusion-Paragraph #1

• The next activity, involved surface area. First step was to place 100 ml of water in 3 different beakers. The second step was to crush one tablet, break a second tablet in eight pieces, and the third tablet remained whole. The last step was to record how long it took for the alka-seltzer tablets at various sizes to dissolve. The various sizes of alka-seltzer represented the independent variable, the dependent variable was the reaction time, and the constant was the amount of water.

Conclusion –Paragraph #1

• The last activity was about pH. This had to do with how varying the pH level of a substance can affect the reaction rate. In this experiment three different pH was used: 0, 3 and 7. The various pH was the independent variable, the reaction rate was the dependent variable and the amount used in each beaker was the constant in the experiment.

Conclusion-Paragraph #2• Refer to your notes on Factors That Affect the Rate of

Reaction.• Start with explaining the “Collision Theory” in your own words.• How does this theory relate to the factors and the reaction

time. • Explain the data collected for each activity:

Activity #1-TemperatureActivity #2-Surface AreaActivity #3-pH

Refer to the analysis questions as well.

Your graph may look similar to this graph for Question #1 of Experiment #1

Conclusion – Paragraph #3

• Indicate whether or not your hypothesis was supported for all three activities. Explain one activity at a time.

• The last part of this paragraph has to do with real-world application and connections. Answer the question. Answer only. How can understanding how fast reaction occurs in the world around us or in industry be beneficial to society as a whole. Give to real-world applications. You must include at least two references for your real-world applications on reaction rate.

-No references = No credit