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 Develop a simple method that allows for capturing the gas released from a chemical reaction Determine the density of the released gas Determine why gas generally moves up and out of a beaker 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 Fill up a graduated cylinder to the very top with warm water (record temperature) Fill a 400 ml ml beaker about ½ full of warm water Cover the top of the cylinder with a piece of aluminum foil Quickly invert the cylinder an place into the beaker Remove the aluminum foil 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 Take a small beaker (100 ml) and fill it with 40 ml of warm water Find the mass of beaker with water and a tablet of antacid, DO NOT put tablet into water during the weigh in Add 1 tablet of antacid to water , let tablet dissolve completely Find the mass of beaker and water after tablet dissolved Clean and dry beaker
Chart for mass of gas before tablet was placed into beaker 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 Aspirin A 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)