Alka Seltzer and density

Density of Gas

Lab

Chem Catalyst• You have seen the

commercials, maybe used the product yourself.

• What is happening when the tablet begins to fizz?

• Does all of the tablet’s initial matter remain in the water? Explain your answer.

• If not, where does it go?

In your comp book…

• Write down the title and goal of the gas density lab.

• Write down the procedure required to obtain the volume of gas released from ½ an antacid tablet.

• Write down the procedure required to obtain the mass of the gas released from ½ an antacid tablet.

Goals

1. Develop a simple method that allows for capturing the gas released from a chemical reaction

2. Determine the density of the released gas3. Determine why gas generally moves up and

out of a beaker4. Determine is a chemical reaction has taken

place

Main ideas

• All matter has density, even if the matter can not be seen

• The density of gas is much less than the density of solids and liquids

• The pressure of the trapped gas on the liquid is greater that external air pressure.

To find the density of anything, what information do you need?

Answer:

• The mass and volume of the object

Materials needed

• 100 ml graduated cylinder• 600 ml griffin beaker, 100ml beaker• Water• 2 antacid tablets (keep these dry until use!)• Piece of aluminum foil• Good eyesight and quick reflexes

To Find the volume of gas

From Antacid tablet

Procedure to determine the volume of gas

a. Fill up a graduated cylinder to the very top with warm water (record temperature)

b. Fill a 400 ml ml beaker about ½ full of warm water

c. Cover the top of the cylinder with a piece of aluminum foil

d. Quickly invert the cylinder an place into the beaker

e. Remove the aluminum foilf. Break an antacid tablet in half

Procedure, part 2

g. Drop ½ of the antacid tablet into the beaker, quickly cover the tablet with the inverted graduated cylinder

h. As antacid dissolves the level of water in cylinder should go down

i. Make sure all pieces of antacid dissolve under the cylinder

j. Repeat procedure with other ½ of tablet.k. Clean up area, wash beaker and cylinder

Volume chart

Antacid Tablet section

Volume of gas (include units)

Temperature of water (⁰C)

1st Piece

2nd Piece

To find the mass of gas from an antacid tablet

Procedure to determine the mass of gas locked in a antacid tablet

1. Take a small beaker (100 ml) and fill it with 40 ml of warm water

2. Find the mass of beaker with water and a tablet of antacid, DO NOT put tablet into water during the weigh in

3. Add 1 tablet of antacid to water , let tablet dissolve completely

4. Find the mass of beaker and water after tablet dissolved

5. Clean and dry beaker

Chart for mass of gas

Description of objects to be measured

Mass value (g)

Mass of all (beaker, water, tablet)

before tablet was placed into beaker

Mass of all (beaker, water,)

after tablet dissolved

Mass of the gas: The difference between the above measures

Temperature of the water value in degrees celsius:

Calculate density of gas

Determine the density of gas :

__________________ g/ml

__________________ g/cm3

List of ingredients of Alka Seltzer

A lot of Baking Powder (BiCarbonate of Soda)A tiny amount of AspirinA small amount of Citric Acid for flavor

What material(s) do you think composes the gas? (Hint: Think of what you exhale with every breath)