experiment 5 chem 101l 2019 lan UNC CHAPEL HILL PDF

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EXPERIMENT 5 UNC LAB 2019 PRE AND POST LAB...

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CHEM 101L Pre-Lab 5

Fall 2019

Name UNC onyen

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 are you measuring; how are you obtaining the fuel; what comparisons are you making)? (2-3 sentences) We will measure out .5g of yeast, 20ml of Hydrogen peroxide, 40 ml of HCL, and 1 gram of zinc metal. We will obtain the fuel by separating the oxygen gas from the reaction mixture, the oxygen gas is produced by the hydrogen peroxide that was decomposed by catalase. We are comparing the launches of four different launches

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(1) Why is this experiment relevant? Think about the reactions you will perform, what measurements you will be doing, and what information you will gather. (3-5 sentences) This experiment is relevant because this week we are conducting two different gas products reactions. We will be measuring two gases, the oxygen gas or the hydrogen gas and will be measuring the distance, sound, accuracy, etc. of each launch. The oxygen gas produced during the reaction will be separated from the reaction mixture. The hydrogen gas will be produced by electrons as zinc metal reacts with hydrochloric acid to produce the gas.

3. (2) What is the purpose of the yeast in this experiment? (be specific; 2-3 sentences) We need to be able to collect the oxygen gas produced from the reaction. The yeast is used to produce an enzyme so we can catalyze the reaction to be able to collect the oxygen gas.

CHEM 101L Pre-Lab 5

Fall 2019

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 a safe tub for the bubble that might drip from the test tubes Conduct the reaction for the oxygen gas Conduct the reaction for the hydrogen gas Get the TA to help us set off our rocket using the gases as fuel to move the rocket Record the distance, accuracy, sound, etc. of each gas

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 (H 2O2) ▪ ▪ ▪ ▪

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Zinc ▪ ▪ ▪

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Health Hazard Information: poses some extreme health risk Potential health hazard: inhalation, eye contact, skin contact, ingestion Hazard Statement: Store with care Prevention: Wear gloves, goggles, no not inhale due to strong odor1

Health Hazard Rating: health-1, flammability- 3 Potential health hazard: eye contact, skin contact, ingestion Prevention: Wear gloves, goggles, no not inhale can irritate nose and throat.

6M HCl ▪ ▪ ▪

Hazard Identification: corrosive, irritant Hazard statement: corrosive to metals, skin burns, eye damage, respiratory irritation, Precautionary statement: have product in container or labeled, keep out of reach of kids, read label, keep in original container, avoid breathing.

CHEM 101L Pre-Lab 5

Fall 2019

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 water is to take care of the bubbles which will occur when pouring your gases in. The water will press or tap the bubbles out.

3. In this experiment, a number of precautions are given to help you be more successful. Provide 1-2 sentences of reasoning for each below: 1. (1) Why do you wait until the rate of bubbling slows in the reaction of yeast and hydrogen peroxide? You need to wait in till the bubbling has slows because you need to collect the gas with your water-filled pipet bulb and need to keep any yeast foam out of the tubing.

2. (1) How is the experiment improved by removing the foam that forms from the yeast reacting with hydrogen peroxide? The experiment is improved from removing the foam because you are collect trying to collect just the oxygen gas not the foam produced from the yeast.

3. (1) Why is it important to wait at least two minutes after adding zinc to collect hydrogen? This will allow time for the air to be purged from the testing tube.

4. (1) What would happen if you used a stopper without a hole in Reaction A? You would not be able to collect the gas using your pipet tub.

5. (1) What would happen if you did not use a stopper in Reaction A? The testing tub would not be sealed all the way and my not mix properly.

CHEM 101L Pre-Lab 5

Fall 2019

6. (1) Why do you need to wait another 1-2 minutes after attaching the stopper before you collect oxygen? This will allow the newly created oxygen to push out the air out of the flask.

7. (1) Why is it important to NOT create a seal between the pipette bulb and the tubing when collecting oxygen gas? You need to leaver a gap so that the water can run out as it is pushed out by the oxygen being collected.

4. (2) Why is it important to prevent mixing of the hydrogen peroxide with the zinc/acid mixture in the waste container? (be specific) Acid mixed with an organic compound, reducing agents and metals can cause an explosion.

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-> ZnCl2(aq)+H2(g)

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(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- oxidized, Hydrogen- reduced

CHEM 101L Pre-Lab 5

o

Fall 2019

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

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+O2 -> 2H20 o

Generate a hypothesis about how each of the following factors might aff ect propulsion. 1. (1) Amount of H2 fuel This fuel is less dense and my make the rocket not travel far if it has too much.

2. Fuel-to-oxygen ratio This needs to be balanced as much as possible to be able to get the best results

3. (1) Order of addition of gases to the rocket (H 2 or O2 first) I don’t believe this is affect the experiment in any way because they will eventually mix.

4. (1) Purity of gases collected—e.g. if Reactions A and B run hot, you may be collecting water vapor in addition to H 2 and O2 This will harm the rockets ability to go because you need try your best to keep the water vapor out of the tube be make sure you are just getting the gasses produced.

TA ONLY: Late Penalty

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