Name________________________________________Date____________ Period__________
Lab: What Effects Reaction Rate
Purpose: To study the effect of changing the concentration of a reactant on the rate of a chemical reaction.
Study the effect of changing the temperature on the rate of a chemical reaction. To formulate hypotheses about
how reaction rates are affected by changes in temperature and changes in concentration of reactants.
Equipment & Materials
Beakers, 40-ml
Thermometer
Solution A (with IO3- ion)
Hot and cold water for part B
Beaker 80-ml
Graduated cylinders (2)
Distilled water
Stop watch
Solution B (with HSO3 ion and soluble starch)
Procedure- It is important that solutions A and B do not mix until you are ready to time. All lab
equipment must contain only A or B and not to be used for both. Labels will be present on the glassware
so please do not mix them up!!!
Part 1: Concentration vs Reaction Time
1. Using a clean, dry, labeled 10-ml graduated cylinder, measure exactly 10.0 ml of Solution A
2. Using a second 10-ml labeled graduated cylinder, measure exactly 10.0 ml of Solution B
3. While one lab partner pours both Solution A and Solution B into a 40 ml beaker, the second partner should
immediately start timing the reaction. Continuously swirl the solution.
4. At the instant a color change occurs, the partner timing the reaction should note the time it took. Record this
in your data table.
5. Pour the changed color solution into the waste beaker (inside the hood).
6. Rinse the 40-ml beaker with distilled water.
7. Repeat the same procedure using the other ratios from the data table.
Part 1 Data
Soln B (ml)
Soln. A
Water
10 ml
10 ml
0 ml
10 ml
8 ml
2 ml (add to A)
10 ml
6 ml
4 ml (add to A)
10 ml
5 ml
5 ml (add to A)
Time (sec)
Part 2: Temperature vs. Reaction Time
1. Measure 10.0 ml of Solution A and 10.0 ml of Solution B using the graduated cylinder.
During this portion of the lab you will obtain either hot or cold water from your teacher.
2. From the teacher, obtain either cold water or hot water in your 80-ml beaker.
3. Put the graduated cylinders to into the 80-ml beaker to cool/heat up the solution.
4. Place the thermometer in one of the test tubes and continue monitoring the temperature of the solutions.
Always rinse and wipe the thermometer after removing it from a solution.
4. When the solutions are almost at the same temperature as the water, prepare to time the reaction. One lab
partner should start timing the reaction the instant the second partner pours Solution A into Solution B in the
small beaker. At the instant a color change occurs, not time elapsed. Measure the temperature of the mixture
immediately. Record the exact temperature and elapsed time in your data table in the correct group (lab table #).
Discard the mixture as instructed. Rinse and dry the graduated cylinders.
5. Record the temperature and elapsed time from the other groups in the class in your data table.
Part 2 Data
Group
1
2
3
4
5
6
7
8
9
Temperature Celsius
Time (sec)
Analysis Questions:
1. Based on your experimental data, make a general statement (hypothesis) about the effect of concentration of
reactants on reaction rate.
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2. Make similar hypothesis about the effect of temperature on reaction rate.
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3. What other factors, beside concentration and temperature affect the reaction rate?
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4. How does the “Collision Theory” relate to the rate of a chemical reaction?
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5. How can a catalyst change your reaction? Explain what a catalyst would do to make change the rate?
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6. Explain why the pressure will not effect this reaction that you did?
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Teacher’s Notes Lab Preparation (iodine clock reaction):
Solution A:
(40 ml per group x 50 groups (5 classes w/ 10 groups each) = 2 Liters total)
4.3 g KIO3 (Potassium Iodate) Per 1 Liter solution (8.6g for 2 Liters)
Simplified – 2000ml H2O + 8.6gKIO3
Solution B:
(50 ml per group x 50 groups (5 classes w/ 10 groups each) = 2.5 Liters total)
2 g NaHSO3 (Sodium Bisulfite) per liter
Simplified – 2500ml H2O + 5gNaHSO3 + 5g starch (potato or corn)
Note: Make the starch solution first use heat to dissolve (may be slight cloudy since not all will dissolved,
decant and add more DI water if desire a clear solution). Wait for the solution to cools and add in NaHSO3
Lab Data
10ml of Solution A + 10ml of Solution B takes about 20 seconds to turn color.
Demo Solution
Potassium Permanganate (2mg in 50ml water) + NaOH (10g) + Sugar (6g in 750ml) give purple, blue, green
and orange as Permanganate loses O ions
Blue bottle http://chemistry.about.com/od/chemistrydemonstrations/ss/bluebottle_2.htm
1.
2.
3.
4.
5.
6.
Half-fill two one-liter Erlenmeyer flasks with tap water.
Dissolve 2.5 g of glucose
Dissolve 2.5 g of sodium hydroxide (NaOH)
Add ~1 ml of 0.1% methylene blue to each flask.
Stopper the flasks and shake them to dissolve the dye. The resulting solution will be blue.
Set the flasks aside (this is a good time to explain the chemistry of the demonstration). The liquid will gradually
become colorless as glucose is oxidized by the dissolved dioxygen. The effect of concentration on reaction rate
should be obvious. The flask with twice the concentration uses the dissolved oxygen in about half the time as the
other solution. A thin blue boundary can be expected to remain at the solution-air interface, since oxygen
remains available via diffusion.
7. The blue color of the solutions can be restored by swirling or shaking the contents of the flask.
8. The reaction can be repeated several times.