chemistry lab

Unit 6 Lab: Properties of Gases

CHEM 1806

Purpose: To observe some properties of gases.

Materials: Student Supplied –matches, toothpicks, pie tin (or something similar), marker, white vinegar, 3% H2O2, measuring spoons, drinking straw, tissue paper, baking soda

LabPaq materials: Goggles, 5 test tubes, 24-well plate, Gas Assembly, pipet, rubbler stopper, #00, 1 hole, pipet tip with plastic gas delivery tube; Properties of Gases Experiment bag.

Procedure:

**Things that might help:

· Light a candle rather than trying to juggle the match and pipet at the same time.

· Put a small amount of water in the bottom of a glass that is not quite as tall as your pipet to store it when it is full of Hydrogen.

Hydrogen Gas

1. Place a small piece of mossy Zn in a test tube with HCl filled to within 1cm of the top of the tube.

2. Cap the test tube with the rubber stopper that has the short, straight, plastic gas delivery tubing in its center.

3. Use tissue to wedge this test tube into the 24-well plate to keep it upright. (I had a stand with my kit. I originally had the wrong materials) And place the whole apparatus in the pie tin. (There will be overflow later. Kitchen sink would work too.)

4. Observe the reaction.

5. Fill a pipet with water, invert and quickly place it on top of the gas delivery tube. The water will be displaced by the gas.

6. When all of the water has been displaced by gas, quickly remove the pipet and place your thumb over the end to keep the gas from escaping.

7. Light a match (I found a candle to be easier for this part). While holding the pipet horizontally, the end about 1 cm from the flame, squeeze a small amount of gas into the flame. Observe what happens and record in the Data Table.

8. Mark the pipet with the marker into about 3 equal parts.

9. Fill the marked pipet with water, invert it, and set it onto the gas generation tube, as before.

10. When the pipet is about 2/3 filled with gas, remove it, keeping it inverted (open end down), in a well that has water in it. (To seal the opening) OR a glass, as mentioned above.

Oxygen Gas

1. Place a few pieces of Mn into a second test tube.

2. Add enough 3% Hydrogen Peroxide (This is standard, pharmacy hydrogen peroxide) to fill the test tube to within 1 cm of the top.

3. Place the rubber stopper with the plastic gas delivery tube into the test tub. Wedge it into the 24-well plate so it stands upright and observe the reaction.

4. Fill a new pipet bulb completely with water, invert, and place it on top of the gas delivery tube, just like with the Hydrogen procedure.

5. When the water has been displaced with oxygen in the collection pipet, remove the pipet and place your thumb over the opening to keep gas from escaping.

6. Light a wooden toothpick, extinguish it and quickly, while still glowing, insert the toothpick into the O2 filled pipet. Record observations.

H2 + O2

** helpful to have the candle lit here.**

1. Take the collection pipet that was set aside from the Hydrogen experiment and place it on the Oxygen generation tube. (The point is to mix the remaining Hydrogen with oxygen.)

2. Collect enough oxygen to displace the remaining hydrogen.

3. Remove the pipet and cap the open end with your thumb to keep the gas from escaping.

4. Holding the pipet horizontally with the open end approximately 1 cm from a flame (candle or match), gently squeeze the contents of the pipet into the flame. Record observations.

5. Rinse the test tube assemblies.

Carbon Dioxide

**Keep the candle lit**

1. Put about 20-30 drops of Limewater into a well of the 24 well plate.

2. Put about 20-30 drops of bromothymol blue into a well of the 24 well plate.

3. Place ½ a teaspoon of sodium bicarbonate in the bottom of a test tube.

4. (There might be overflow here) Add half a pipet full, not an exact measurement, of white vinegar to the test tube. The reaction will be violent.

5. When the reaction has subsided, put the stopper with the copper and plastic tube on the test tube.

6. Place the open end of the gas delivery tube into the limewater that is in the well of the well plate.

7. Record observations.

8. Rinse the delivery tube carefully.

9. Place the gas delivery tube in the bromothymol blue and observe.

10. Light a tooth pick or match and place inside the test tube (have to remove stopper assembly first)

11. Record observations.

(2 pts) Data Table:

	Flame Reaction	Glowing Splint	Limewater Reaction	Bromothymol Blue
H2
O2
H2 and O2
CO2

Results and Discussion:

1. (4 pts) Why did the observed flame and glowing splint tests have the results they did?

2. (4 pts) Describe how the limewater reacted with the carbon dioxide.

3. (4 pts) Explain why the Carbon dioxide reacted with the bromothymol blue like it did.

4. (2 pts) I commonly use the carbon dioxide generation to “pour” CO2 on a lit candle. It is fun to watch but WHY is it possible. What happens with carbon dioxide and a lit match? Explain.

5. (4 pts) Insert a picture of one part of your set up.

When you are finished, save the file as LASTNAME_Gases and upload it to the Dropbox for Unit 6 Labs.