Experiment 5 Pre-Lab PDF

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Experiment 5 Pre-Lab...

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CHEM 101L Pre-Lab 5

Fall 2021

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UNC ONYEN

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Experiment 5: Gas Forming Reactions and Rockets Experiment #5 Pre-Lab Assignment Instructions: 1. When answering questions, do not repeat or copy from the lab manual. You are encouraged to use the Lab Manual as a reference, but plagiarized answers will not be graded. 2. Do not ever work to answer these questions with a partner - avoid plagiarism and cheating. 3. Do not exceed the limit given for each question. 4. Do not remove instructions or any bolded text. This section will help prepare you for writing an introduction for future experiments: 1. (2) What is the objective of this lab (what will be measured; how will fuel be obtained; what comparisons are you making)? (2-3 sentences)

The objective of this lab is to understand the usefulness of a catalyst in chemical reactions and use one to increase the rate of a reaction that produces gas. Fuel will be obtained from combustion reactions to propel a mini-rocket. 2.

(1) Why is this experiment relevant? Think about the reactions that will be performed, what measurements will be done, and what information will be gathered. (3-5 sentences)

This experiment is relevant because implimenting a catalyst can increase the rate of a reaction without influencing the energy of products or reactants and can produce gas faster. The catalyst Is not included in products or reactants because it is not consumed and it recycled to its original state to be reused. We will measure the efficiency of each rocket with the different gases to see which one performs the best.

3. (2) What is the purpose of the yeast in this experiment? (be specific; 2-3 sentences) Yeast produced an enzyme called catalase, nature's catalyst, which is a single-celled microorganism. This catalase is able to decompose 60 million molecules of hydrogen peroxide per second. So this catalase from yeast is used as a catalyst to break down hydrogen peroxide to get oxygen gas by itself as a gas.

CHEM 101L Pre-Lab 5

Fall 2021

4. (4) Summarize this experiment: Provide a bulleted list of tasks for this experiment, using 1 phrase or sentence per bullet. You can use a maximum of 5 bullet points to describe Experiment 5.

1)Prepare two gas-generating setups with plastic tubing and a half-filled water tub. 2)Combine yeast and hydrogen peroxide in the first tube until it starts to bubble and foam is created then remove the foam and place rubber stopper 3)Wait two minutes to collect gas with callibrated pippette bulb. 4) add mossy zinc to hydrochloric acid in test tube and add rubber stopper then wait two minutes to collect gas. 5) Ask TA to launch the rockets and record details of This next section is designed to prepare you for the experimental portion of the experiment, as well as your discussion an analysis after the experiment. Answer each question carefully. You may need to reference the lab manual or textbook to answer these questions. For some questions, you will likely need to think carefully about the reasoning (the answer won't be exactly written in a book!). 1. (3) Look up (use an internet search engine) and reference the SDS (Safety Data Sheet) for 3% hydrogen peroxide (H2O2), zinc, and 6M HCl. Report the health hazard ratings, one potential hazard and one prevention method for both compounds below. o 3% Hydrogen peroxide (H2O2) -Health Hazard Information: NFPA scale; 0 health, 0 flammability, 0 reactivity, 0 specific hazard - Potential Health Hazard: Can cause severe skin burns and eye damage -Hazard statement: May cause fire or explosion, strong oxidizer -Prevention: keep away from heat, sparks, open flames, or hot surfaces.

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Zinc -Health Hazard information: 3 health, 0 flammabiltiy, 0 reactivity, 0 specific hazard - Potential Health Hazard: causes serious eye damage, harmful if swallowed -Hazard statement: Very toxic to aquatic life with long lasting effects - Prevention: wear propper PPE, wash skin thoroughly and avoid release to environment

6M HCl

CHEM 101L Pre-Lab 5

Fall 2021

-Health Hazard Information: 3 health, 0 flammabiltiy, 0 reactivity, 0 specific hazard - Potential Health Hazard: Causes severe skin burns and eye damage, may cause respiratory irritation -Hazard statement: may be corrosive to metals -Prevention: keep only in original container, avoid breathing dust/fumes/gas/vapors, etc.

2. (1) In this experiment, you are instructed to fill the calibrated pipette bulb with water prior to gas collection. Why? (1-2 sentences)

The calibrated pipette bulb is filled with water prior to gas collection so it can be displaced with hydrogen and then oxygen.

3. In this experiment, a number of recommendations are given to better ensure success. Provide 1-2 sentences of reasoning for each below: o

(1) Why do you wait until the rate of bubbling slows in the reaction of yeast and hydrogen peroxide?

You wait for the rate of bubbling to slow in the reaction of yeast and hydrogen peroxide to ensure that the reaction is done taking place.

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(1) How is the experiment improved by removing the foam that forms from the yeast reacting with hydrogen peroxide?

Th experiment is improved by removing the foam that forms because the foam can prevent the collection of hydrogen from the reaction.

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(1) Why is it important to wait at least two minutes after adding zinc to collect hydrogen?

It is important to wait at least 2 minutes so ensure that the hydrogen gas is done forming after you removed the foam.

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(1) What would happen if you used a stopper without a hole in Reaction A?

CHEM 101L Pre-Lab 5

Fall 2021

If we used a stopper without a hole in Reaction A, the tube would explode from the pressure of the built up gas.

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(1) What would happen if you did not use a stopper in Reaction A?

If we did not use a stopper, the gas would escape the tube without us being able to measure it.

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(1) Why do you need to wait another 1-2 minutes after attaching the stopper before you collect oxygen?

Waiting a couple of minutes make sure that the reaction has sped up and slowed down so that you can collect the foam and let the reaction continue to produce more oxygen.

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(1) Why is it important to NOT create a seal between the pipette bulb and the tubing when collecting oxygen gas?

It is important not to create a seal so that the water can run out of the pipette bulb.

2. (2) Why is it important to prevent mixing of the hydrogen peroxide with the zinc/acid mixture in the waste container? (be specific) Hydrogen peroxide and the zinc/acid mixture are both hazardous materials that if mixed together in the waste container would cause another chemical reaction which could be extremely dangerous and potentially cause an explosion. 1. Write out the following equations for a reaction between Zinc and HCl. All equations must be balanced and include states of matter to receive credit: o (1) Balanced Molecular Equation Zn(s) +2HCl (aq) ----> ZnCl2 (aq) + H2 (g) o

(2) Complete Ionic Equation

CHEM 101L Pre-Lab 5

Fall 2021

Zn (s) + 2H^+(aq) + 2Cl^-(aq) ----> Zn ^2+ (aq) +2Cl^-(aq)+ H2(g) o

(2) Net Ionic Equation Zn(s) + 2H^+(aq) ----> Zn^2+(aq) + H2(g) (2) Which element undergoes reduction, and which oxidation?

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Zinc is oxidized and hydrogen is reduced

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(1) Which species does not change electronic state, and is therefore a spectator ion? Chlorine

2. (1) Write out and balance Reaction C from the lab manual and use this equation and your knowledge of combustion reactions to generate hypotheses from the prompts below (include states of matter): 2H2(g) +O2(g)-----> 2H2O(aq) o

Generate a hypothesis about how each of the following factors might affect propulsion. 

(1) Amount of H2 fuel

With more H2 fuel, the rocket will propel farther because H2 is highly flammable



Fuel-to-oxygen ratio

The more oxygen there is, the combustion will create more energy that propels the rocket farther.

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(1) Order of addition of gases to the rocket (H2 or O2 first)

CHEM 101L Pre-Lab 5

Fall 2021

Adding oxygen first will lead to a better propulsion of the rocket becayse H2 can escape more easily.

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(1) Purity of gases collected—e.g. if Reactions A and B run hot, you may be collecting water vapor in addition to H2 and O2

Since pure oxygen and hydrogen are highly flammable, the more pure the substances are, the more energy they will create to launch the rocket further.

TA ONLY:

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