Experiment 5 Post Lab PDF

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Completed post lab for experiment 5. It is for Chemistry 101 Lab 2021/22...

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CHEM 101L Pre-Lab 5

Fall 2021

Name

Joe Smoe

UNC ONYEN

Joesmoe

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 is to measure and observe how different reactions can create gas and also use gas in order to create a rocket fuel out of the gases we obtained. We'll obtain the H2 gas from the redox reaction of zinc & hydrochloric acid and O2 from the decomposition of H2O2. We are comparing how these gases react to fire. 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 it represents decomposition reactions as well as combustion reactions and oxidation- reduction reactions. We will observe how H2 and O2 gases are products of two different reactions and collect these products for use as a fuel during a combustion reaction. We will gather information on how each of these gases react when ignited.

3. (2) What is the purpose of the yeast in this experiment? (be specific; 2-3 sentences) The yeast in this experiment is used to catalyze (speed up) the reaction between hydrogen peroxide through its production of catalase. The catalase will break down the hydrogen peroxide and produce oxygen gas from the reaction.

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.

-Set up apparatus to retrieve the gases from the reactions -Add yeast and hydrogen peroxide to test tube and collect O2 gas -Add zinc and hydrochloric acid to test tube and collect H2 gas -Decide ratio of H2 and O2 gases for rocket fuel and fill pipette according to optimal fuel ratio -Use pipette and observe results of the ignition of gas as rocket fuel 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: HMIS 0-4, irritant Potential health hazard: Harmful if swallowed, corrosive to skin and eyes , dangerous if inhaled Hazard statement: May cause fire or explosion, harmful if swallowed, severe skin burns and eye damage, harmful if inhaled Prevention: keep out of reach of children, read label before each use, keep away from heat/ open flame, wash after handling, wear proper PPE, do not eat or drink o

Zinc -Health Hazard Information: Corrosive category 1, Irritant category 4, environmentally damaging category 1 -Potential Health Hazard: eye damage, intestinal damage, skin damage, harmful if inhaled -Hazard Statement: causes serious eye damage, harmful if swallowed, very toxic to aquatic life with long lasting effects -Prevention: keep out of reach of children, do not eat drink or smoke when using, wear protective PPE, wash skin after handling, avoid release to environment, if swalled call poision

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6M HCl -Health Hazard Information: corrosive category 1, serious eye damage category 1, irritant category 3 -Potential Health Hazard:Harmful if swallowed or inhaled, can cause severe burns & eye damage -Hazard Statement: may be corrosive to metals, causes severe skin burns and eye damage, may cause respiratory irritation, causes serious eye damage Prevention: keep out of reach of children, keep in original container, avoid inhaling, wash throroughly after handling, use in well ventilated area, wear proper PPE

CHEM 101L Pre-Lab 5

Fall 2021

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

Filling the pipette with water prior to collecting the gas will allow us to measure how much of the gas is collected when the water is displaced.

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?

We wait in order to ensure the yeast has fully catalyzed the hydrogen peroxide into oxygen gas. This will allow the foam to stop forming so that it may be removed.

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

This ensures that foam will not get into the tubing and affect the collection of oxygen.

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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 after adding zinc to collect hydrogen in order to ensure that the pipette only collects the hydrogen gas.

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

The reaction would result in a build up of pressure and gasses that could cause an explosion.

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

The gaseous products from the reaction would be released into the environment.

CHEM 101L Pre-Lab 5 o

Fall 2021

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

Waiting ensures that your collection is purely O2. This gives time for the reaction to fully occur and displace the air with oxygen gas.

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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?

The water is displaced by the oxygen gas, so if there is a seal the water will not be able to flow out of the tube.

4. (2) Why is it important to prevent mixing of the hydrogen peroxide with the zinc/acid mixture in the waste container? (be specific)

The mixture of hydrogen peroxide with the zinc/acid mixture in the waste container could potentially result in a combustion reaction which could be harmful.

5. 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 Zn (s) + 2H+(aq) + 2Cl- (aq) --> Zn 2+ (aq) + 2Cl - (aq) + H2 (g)

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(2) Net Ionic Equation Zn (s) + 2H+ (aq) --> Zn 2+ (aq) + H2 (g)

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(2) Which element undergoes reduction, and which oxidation? Zinc gets oxidized and hydrogen gets reduced.

CHEM 101L Pre-Lab 5

o

Fall 2021

(1) Which species does not change electronic state, and is therefore a spectator ion? Chloride (2Cl- (aq))

6. (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 (l) o

Generate a hypothesis about how each of the following factors might a ff ect propulsion. § (1) Amount of H2 fuel

The H2 fuel will allow for a stronger combustion reaction, thus the more hydrogen fuel, the stronger the reaction will be and the further the rocket will propel.

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Fuel-to-oxygen ratio The fuel to oxygen ratio will determine how the combustion reaction takes place, how much energy is released and how much oxygen is used up in the reaction. The more fuel, the better the propulsion.

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

Adding O2 first will increase the combustion reaction as hydrogen combusts with the available oxygen. This will cause the propulsion to go further.

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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

The collection of water vapor in addition to the gases will disrupt the reaction taking place, thus inhibiting the propulsion that will occur from the reaction.

TA ONLY:

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