CHEM 404 Lecture Notes - Lecture 9: Redox, Test Tube, Sodium Chloride

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orangewolf816

18 Jan 2020

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Added 8 drops of starch ml to be added. I chose these particular amounts because i wanted the reaction to be more intense than the one we did in part 3 so i could more easily see the color changes and they were more dramatic. We decided to multiply the values given by four in order to achieve this. One of the times we had predicted were in range. Reaction c behaved predictably would be quick because there is less na2s2o3 in the solution than the other reactions. Na2s2o3 helped to make the reaction quicker because it used the electrons from iodine, which was more concentrated in this reaction. When these two reactants react, it forms nai which we observe as the dark blue color. 2na2s2o3 (aq) + 12 (aq) 2nai (aq) + na2s4o6 (aq) Reaction b took longer than we had predicted, but overall it had acted predictably. We predicted that reaction be b would only take thirty seconds.

Related Questions

A student is performing rate measurements for the reaction of I- with H2O2 in a buffer solution. The rate law for the reaction is known to be Rate = kâ[I- ]^1 [H2O2]^1 . The student mixed 6 ml of DI water, 1.0 ml of Buffer, 1 ml of 0.3 M KI, 1 ml of 0.02 M Na2S2O3, 1 ml of 0.1 M H2O2 and 5 drops of starch and notices a color change after 54 seconds. What time would it take the solution to change the color if:

a) The concentrations of both KI and H2O2 were decreased by a factor of 2.

b) The concentration of Na2S2O3 was increased by a factor of 2.

Please check my work. I am have to bring my grade up so I need to make sure I get these right this week Here are my notes and answers from lab this week please let me know if I missed any.

NOTES:

Experiment 1: The Effect of Temperature on Catalase Activity

Test tube #1(10ÃÂ°C)

Add 5 mL of 3% hydrogen peroxide

Add 5 mL of water

Add 1 mL of catalase

Observe bubbles: No bubbles observed (or very, very little)

Color changed to red

Test Tube #2 (21.5ÃÂ°C)

Add 5 mL of 3% hydrogen peroxide

Add 5 mL of water

Add 1 mL of catalase

Observe bubbles: Bubbles appeared quickly and constantly for the first 10 seconds then stopped

Color changed to red

Test Tube #3 (40ÃÂ°C)

Add 5 mL of 3% hydrogen peroxide

Add 5 mL of water

Add 1 mL of catalase

Observe bubbles:Bubbles appeared slowly and Sporadically for about 10 seconds then stopped.

Color changed to red

Test Tube #4(60ÃÂ°C)

Add 5 mL of 3% hydrogen peroxide

Add 5 mL of water

Add 1 mL of catalase

Observe bubbles: Bubbles appeared instantly and continued sporadically continued for 10 seconds

color changed to red

Test Tube #5 (80ÃÂ°C)

Add 5 mL of 3% hydrogen peroxide

Add 5 mL of water

Add 1 mL of catalase

Observe bubbles:Bubbles appeared instantly, and sporadically continued for about 10 seconds then stopped.

Color of solution changed to red.

Experiment 2: The Effect of Substrate Concentration on Catalase Activity

Test Tube #1

Add 8mL Water

Add 2mL 3% Hydrogen Peroxide (mL)

Add 0.1 mL of catalase

Time for bubbles to stop forming: .38 seconds

Test Tube #2

Add 5mL Water

Add 5mL 3% Hydrogen Peroxide (mL)

Add 0.1 mL of catalase

Time for bubbles to stop forming: 32 seconds

Test Tube #3

Add 2mL Water

Add 8mL 3% Hydrogen Peroxide (mL)

Add 0.1 mL of catalase

Time for bubbles to stop forming: 28 seconds

Test Tube #4

Add 0mL Water

Add 10mL 3% Hydrogen Peroxide (mL)

Add 0.1 mL of catalase

Time for bubbles to stop forming: No bubbles

Experiment 3: The Effect of pH on Catalase Activity

Test Tube #1 (21.5ÃÂ°C)

Add 5 mL of 3% hydrogen peroxide

Add 5 mL of pH 2 buffer

Add 1 mL of Catalase Solution

Observation: No bubbles

Test Tube #2 (40ÃÂ°C)

Add 5 mL of 3% hydrogen peroxide

Add 5 mL of pH 6 buffer

Add 1 mL of Catalase Solution

Observation: bubbles appear immediately

Test Tube #3 (60ÃÂ°C)

Add 5 mL of 3% hydrogen peroxide

Add 10mL of pH 10 buffer

Add 1 mL of Catalase Solution

Observation: no bubbles.

Experiment 1: The Effect of Temperature on Catalase Activity

Lab Results

At which temperatures did catalase function somewhat, but not optimally?

40 degrees the bubbles appeared slowly and continued sporadically for about 10 seconds before stopping. At 60 & 80 degrees the bubbles appeared immediately but were sporadic as well.

Data Analysis

Why did catalase fail to function at 80 Â°C?

Because the Enzyme catalase denatures

Experiment 2: The Effect of Substrate Concentration on Catalase Activity

Lab Results

Fill in the table below with your results from the substrate concentration experiment.

Substrate Concentration Results
Test Tube	Bubbles Formation (min)
1	00:38 seconds
2	00:32 seconds
3	00:28 seconds
4	No bubbles.

Data Analysis

Before the catalase concentration was saturated with hydrogen peroxide, why did the enzyme function vary with substrate concentration?

The enzymes had varied results before the catalyst concentration was changed due to the differences in temperature. In experiment one all measurements were the same, the variable was the temperature. In experiment two, the concentrations of each material were the variable along with the temperature.

Experiment 3: The Effect of pH on Catalase Activity

Lab Results

What was the pH value at which catalase functioned the best?

pH 6 buffer

Data Analysis

Why did catalase only function in a limited range of pH values?

Conclusions

What are the enzyme, substrate, and product in these experiments?

The enzyme is Catalase

The Substrate is Hydrogen peroxide

The product was the bubbles.

What role does catalase play in the mammalian liver, or any other cell it is found in?

Catalase is an enzyme in the liver that breaks down harmful hydrogen peroxide into oxygen and water. When this reaction occurs, oxygen gas bubbles escape and create foam.

Reference:

https://www.scientificamerican.com/article/bring-science-home-liver-helping-enzymes/

A student is performing rate measurements for the reaction of I^- with H₂O₂ in a buffer solution. The rate law for the reaction is known to be Rate = kâ[I^-]¹[H₂O₂]¹. The student mixed 6 ml of DI water, 1.0 ml of Buffer, 1 ml of 0.3 M KI, 1 ml of 0.02 M Na₂S₂O₃,1 ml of 0.1 M H₂O₂ and 5 drops of starch and notices a color change after 54 seconds. What time would it take the solution to change the color if:

a) The concentrations of both KI and H2O2 were decreased by a factor of 2

b) The concentration of Na2S2O3 was increased by a factor of 2.

CHEM 404 Lecture Notes - Lecture 9: Redox, Test Tube, Sodium Chloride

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