EXPERIMENT: EFFECT OF SOLUTION CONCENTRATION ON REACTION RATE You have learned that as the concentration of reactants increases, there will most likely be a greater number of collisions, and hence increase the rate of a reaction. In this experiment, you will see a demonstration of this, with a twist. There will be three reactions going on in this experiment.

Objectives

Determine how solution concentration can affect the rate of a reaction.

The first reaction will be a reaction of the iodide ion (I-1) with hydrogen peroxide (H2O2) in an acidic solution. This reaction produces a slightly orange solution. In our experiment, we will add some orange food coloring to make this solution more orange.

2 H+ (aq) + 2 I- (aq) + H2O2 (aq) ⟶ I2 (aq) + 2 H2O (l)

The next reaction will be between the iodine and starch

I2 + starch ⟶ I2-starch complex (blue-black)

So, when starch is added to the iodine solution made from the first reaction, the solution will turn black immediately, so it is difficult to find the rate of reaction. In order to be able to time this reaction, you will slow it down with another reaction. Adding ascorbic acid will react with the iodine, reducing the concentration of the iodine available to react with the starch.

C6H8O6 (aq) + I2 (aq) ⟶ 2I- (aq) + C6H6O6 (aq) + 2 H+ (aq)

When the ascorbic acid is used up, the remaining iodine molecules can react with the starch and form the black color. The more ascorbic acid you add, the slower the reaction to form the iodine-starch complex will be.

Online Lab

Before you watch the video, make a hypothesis about the effect of increasing the amount of ascorbic acid will have on the rate of reaction. As you watch the video, make sure to carefully record your data and observations in your data table.

Use your data and observations to complete the assignment.

Analysis and Conclusions

Submit your data and the answers to these questions in the essay box below.

What was your hypothesis?

Plot your data as drops of ascorbic acid vs. time.

As the concentration of ascorbic acid was increased, did the rate of the formation of the iodine-starch complex increase or decrease? Explain your answer in terms of the chemical reactions involved.

Was your hypothesis correct?

Make a general rule about the effects of concentration of reactants on reaction rates.

For practice, the molecular formula for ascorbic acid is C6H8O6, and you used 6 g in this experiment, calculate the molarity of the ascorbic acid. Now calculate the concentration in moles per drop (assume 1 mL = 20 drops).

it wont let me link the video so here are the transcripts: This experiment will demonstrate how the solution concentration can affect the rate of a reaction. The materials for this experiment are:
5 one-hundred milliliter beakers, medium clear glasses or cups
5 fifty milliliter beakers, small clear glasses or cups
2 one-hundred-fifty milliliter Erlenmeyer flasks, large clear glasses, or cups
a one-hundred milliliter graduated cylinder or measuring cup
eye droppers or pipets
balance
a stop watch
digital time or clock with a second hand
water
3% hydrogen peroxide
yellow and red food dye
vinegar
laundry starch
decolorized idodine (not tincture of iodine)
and ascorbic acid in the form of a produce protector, such as Fruit Fresh.

Your job is to observe the experiment and collect your own data from this demonstration.
Step one: To begin, add ten milliliters of three percent hydrogen peroxide to each of the five one hundred milliliter beakers or medium glasses.
Step two: Add one hundred milliliters of vinegar to a one hundred-fifty milliliter Erlenmeyer flask or clear cup. Then add two or three drops of red and yellow food dye to the vinegar.
Step three: Add ten milliliters of the colored vinegar to each of the five fifty milliliters beakers.
Label the beakers A, B, C, D and E.
Step four: Add ten drops of laundry starch to each of the beakers containing the vinegar.
Step five: Add one milliliter or 20 drops of the decolorized iodine to each the the beakers containing the vinegar.
Step six: Measure out 6 grams of ascorbic acid (like Fruit Fresh) and add to a clean Erlenmeyer flask.
Step seven: Add one hundred milliliter of water to the ascorbic acid in the flask and swirl or stir to dissolve the ascorbic acid.
Step eight: Add ascorbic acid to each of the small beakers as follows:
Beaker A: 5 drops
Beaker B: 10 drops
Beaker C: 15 drops
Beaker D: 20 drops
Beaker E: 25 drops
Step nine: You will time how long it takes the solution to turn black.
With the timer ready, add the contents of Beaker A to the first larger flask and time the reaction, record your data in the data sheet.
Step ten: Add the contents of Beaker B to the second larger flask and record the time of reaction.
Step eleven: Repeat with Beaker C.
Step twelve: Repeat with Beaker D.
Step thirteen: Repeat with Beaker E.
Now you can use your data and observations to complete the assignment.