How Much Is a Mole?

Introduction

What does a mole of gas look like? Throw away those boring 22.4 L cardboard cubes and instead produce this volume of gas before the students’ very eyes!

Concepts

• Eudiometer
• Stoichiometry
• Ideal gas law

Background

A eudiometer is a clear, graduated cylinder or container used to measure the volume of gases produced in chemical reactions. While most have a volume capacity of 50–100 mL, the one used in this demonstration has a capacity of 24 L.

The eudiometer chamber is first filled with water. The system is closed and the reaction vessel is connected to the eudiometer. The eudiometer is then opened to the reaction vessel, the gas-producing reaction is started, and the gas produced dramatically displaces the water in the eudiometer. Once the reaction is complete, the volume of gas in the eudiometer can be measured.

The ideal gas law and the stoichiometry of the gas-producing reaction are used to calculate the theoretical volume of gas produced. Consider the reaction used in Demonstration 1:

One mole of CO₂ gas is produced for every mole of sodium bicarbonate reacted. The moles of gas produced (n_CO2) can be calculated from the mass of sodium bicarbonate used in the reaction.

From the ideal gas law, the volume of CO₂ produced, V_CO2, depends on the temperature and pressure, according to the following equation:

where R is the universal gas constant

while T is the temperature in K, and P is the pressure in atmospheres.

At standard temperature and pressure (STP), T is 273.15 K, and P is 1 atm. If one mole of gas is produced, this translates to 22.4 L of gas at STP. The mass of sodium bicarbonate used in the reaction, divided by its molar mass and multiplied by 22.4 L yields the theoretical volume of gas produced at 0 °C and 1 atm pressure.

The total moles of gas contained in the eudiometer is equal to the moles of CO₂ produced and the moles of water vapor above the liquid. The total pressure of the system, using Dalton’s Law, is equal to the sum of the partial pressure of the components.

P_T = P_CO2 + P_H2O

The pressure due to CO₂ is equal to the total pressure of the gases in the eudiometer minus the vapor pressure of water.

P_CO2 = P_T – P_H2O

The volume of CO₂ collected will be measured at laboratory conditions of temperature and pressure. If we let

V₁ = volume of gas collected, (L)
T₁ = temperature of gas collected (K)
P₁ = pressure of gas collected (P_T – P_H2O)

the moles of gas collected equal then at standard temperature and pressure this equation becomes where V₂ is the volume of gas collected at standard temperature and pressure.

Combining these equations yields By rearranging the equation and substituting (P_T – P_H2O) for P₁, the volume of collected gas at STP, (V₂), can be calculated. This value is compared to the theoretical volume of CO₂ and the percent error is determined.

Three lab demonstrations are included with this kit. The first uses the reaction of sodium bicarbonate with hydrochloric acid to produce carbon dioxide. The second involves the conversion of a liquid, N₂(l), or a solid, CO₂(s), to the gas phase. The final demonstration has an active metal reacting with an acid to form hydrogen gas.

Each demonstration will utilize the following procedure for preparing the eudiometer.

Experiment Overview

Lab Demo 1: The Reaction of a Bicarbonate With an Acid
Carbon dioxide gas is produced when sodium bicarbonate is reacted with an acid, like hydrochloric acid. This is a bubbling, visual reaction. The production of gas occurs very fast, but the reaction is not quite as dramatic as the reaction between an active metal and an acid.

Lab Demo 2: Converting One Mole of Liquid or Solid to One Mole of Gas
The traditional method for calculating molar volumes involves generating oxygen gas—potassium chlorate is heated with manganese dioxide, a catalyst, to produce oxygen gas. This method is quite hazardous because large amounts of oxygen gas are produced and potassium chlorate is a powerful oxidizer of organic materials including the rubber stopper used in the setup. In fact, potassium chlorate is a frequent source of accidents on school premises. An easier and safer method presented in this laboratory activity for the calculation of molar volumes involves the use of carbon dioxide or liquid nitrogen instead of oxygen gas.

N₂(l) —> N₂(g)
CO₂(s) —> CO₂(g)

Lab Demo 3: The Reaction of an Active Metal With an Acid
When magnesium metal reacts with hydrochloric acid, hydrogen is produced. The gas can be collected in a eudiometer where its volume may be determined. Knowing the number of moles of magnesium used, we can calculate the volume of hydrogen produced per mole of magnesium consumed. The balanced equation for this reaction allows us to determine the volume of one mole of gas at standard temperature and pressure.

Metal + Acid —> Hydrogen Gas + a Salt

Materials

Safety Precautions

Use glass insertion safety tips when inserting glass tubes into rubber stoppers. Concentrated hydrochloric acid is very corrosive to all body tissue, especially skin and eyes. It is also toxic by ingestion and inhalation. Check all connections and follow directions very carefully—created gases in a closed system can be hazardous. Liquid nitrogen boils at –195.79 °C and dry ice sublimes at –78.48 °C. Both can easily cause frostbite. Do not inhale the gases. Perform this demonstration in a well-ventilated room. Wear fully insulated gloves which are able to withstand low temperatures. Also, wear chemical splash goggles and a chemical-resistant apron. Before stoppering the Erlenmeyer flask, make sure the rubber stopper has been removed from the base of the eudiometer. Open the stopcock immediately after stoppering the flask. This will prevent a possible buildup of pressure which could result in an explosion of the apparatus! If the balloon starts to inflate excessively, immediately make sure the stopcock is opened and the stopper has been removed from the base of the eudiometer. Lab Demo 3 should be a science teacher demonstration only! Acids are corrosive to skin and eyes and are toxic by ingestion. A large amount of hydrogen gas is produced in this demonstration. Hydrogen is potentially explosive when mixed with oxygen. Do not perform this demonstration near an open flame or spark. Use extreme caution. Do not inhale the hydrogen gas. Perform this procedure in a well-ventilated room. Read all available safety information on each chemical used in this demonstration. Before stoppering the Erlenmeyer flask, make sure the rubber stopper has been removed from the base of the eudiometer. Immediately after stoppering the Erlenmeyer flask, open the stopcock to prevent a buildup of pressure, which could result in an explosion of the apparatus. If the balloon starts to inflate excessively, immediately make sure the stopcock is opened and the stopper has been removed from the base of the eudiometer. The reaction between an active metal and an acid is highly exothermic. Wear insulated gloves when handling the flask during the reaction. Cool the flask in an ice/water bath. Do not use metal powder; use metal turnings. Use only one-half mole or less of metal turnings. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron when performing any of these demonstrations. The mole eudiometer should be a science teacher demonstration only! Do not allow students to perform any of the procedures. Please review current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulation that may apply, before proceeding. For Lab Demos 1 and 3, check the pH of the solution in the Erlenmeyer flask and neutralize, if needed. The neutral contents of the Erlenmeyer flask and overflow container may be disposed of down the drain with excess water according to Flinn Suggested Disposal Method #26b. The contents of the overflow container in Lab Demo 2 may be disposed of down the drain with excess water according to Flinn Suggested Disposal Method #26b.

Prelab Preparation

Preparation of Mole Eudiometer

1. Place the empty 24-L eudiometer chamber into the overflow tank.
2. Lightly plug the bottom hole of the eudiometer with a size 4 solid rubber stopper.
3. Insert the temperature probe into a size 4, one-hole rubber stopper.
4. Insert a 3-inch glass tube into the other size 4, one-hole rubber stopper.
5. Insert a 3-inch glass tube into the size 10, one-hole rubber stopper.
6. Insert a 3-inch glass tube into the size 1, one-hole rubber stopper.
7. Insert the stopper with the temperature probe into the side hole of the eudiometer. Twist and push the stopper slightly to create a tight seal to prevent leakage when the eudiometer is filled (see Figure 1).
   {13884_Preparation_Figure_1}
8. Fill the overflow tank with water until the water level is about 1 inch above the bottom-stoppered hole.
9. Fill the eudiometer with water until the water level reaches the top. The stoppers in the side holes may have to be tightened to prevent leakage.
10. Attach the two-way valve to one end of the 66-inch piece of plastic tubing. Attach the glass tube/size 4 stopper assembly to the other end of the plastic tubing (from step 4).
11. Place the size 4 stopper, attached to the two-way valve, in the top hole of the eudiometer. Close the two-way valve so the eudiometer is sealed from the atmosphere.
12. Attach the 18-inch and two 3-inch pieces of plastic tubing to the T-connector. The 18-inch piece should be on one of the side connections.
13. Attach the other end of the 18-inch piece of plastic tubing to the glass tube/size 10 rubber stopper assembly (from step 5).
14. Attach the “right angle,” 3-inch piece of plastic tubing to the glass tube/size 1 rubber stopper assembly (from step 6).
15. Place a balloon over the end of the glass tube/size 1 rubber stopper assembly (see Figure 2).
    {13884_Preparation_Figure_2}
16. Attach the other 3-inch piece of plastic tubing to the two-way valve (see Figure 3).
    {13884_Preparation_Figure_3}
17. Make sure all fittings are tight.
18. Remove the bottom stopper from the side of the eudiometer. There should be a small drop in the water level inside the eudiometer (about ½-L). The level should then remain constant. Note: If the eudiometer leaks air slightly from the top, a light coating of stopcock grease can restore the seal.
19. Replace the bottom stopper to the side of the eudiometer (see Figure 3).
20. The eudiometer is now ready for the demonstration.

Preparation of Acid Cylinder

1. The base and the lip of the plastic 100-mL graduated cylinder may have to be removed to fit into a 2- or 4-L Erlenmeyer flask.
2. Carefully remove the base of the plastic graduated cylinder with a sharp knife or box cutter. Leave the bottom of the cylinder—just remove the “edges.”
3. If the pour spout of the graduated cylinder is too large to fit into the Erlenmeyer flask, trim it off with a sharp knife or box cutter.
4. Use this plastic tube for Demonstrations 1 and 3. Never use a glass tube inside the Erlenmeyer flask.

Lab Demo 1: The Reaction of a Bicarbonate With an Acid

Predemonstration Measurements and Calculations

1. Determine whether a mole or simple fraction of a mole of sodium bicarbonate will be used. Record this value in Part I of the data table. The data table can be handed out or placed on an overhead projector.
2. Calculate the mass of sodium bicarbonate needed. The molar mass of sodium bicarbonate is 84.01 g/mole. Record this value in the data table.
3. Concentrated hydrochloric acid is 12 molar in HCl—83 mL contains 1 mole of HCl. Determine the volume of concentrated hydrochloric acid needed to completely react with the selected moles of sodium bicarbonate. Record this value in the data table. Fill out the rest of Part I of the data table.
4. Using a temperature probe, measure the temperature of the water in the eudiometer. Record this value in Part II of the data table.
5. Look up the vapor pressure of water at this temperature in the tables at the bottom of the data table and record the value in Part II of the data table.
6. Calculate the volume of CO₂ gas that would be produced, at standard temperature and pressure, from the selected amounts of sodium bicarbonate and hydrochloric acid. Record this value as theoretical volume of CO₂(g) in Part II of the data table.

Procedure

Lab Demo 1: The Reaction of a Bicarbonate With an Acid

1. Check to make sure the rubber stopper fits correctly into the Erlenmeyer flask (see Figure 4). A 2- or 4-L Erlenmeyer flask is recommended.
   {13884_Procedure_Figure_4}
2. Remove the rubber stopper from the Erlenmeyer flask.
3. Open the two-way valve to let air into the eudiometer and slowly add air until the water level reaches 20.0 L in the eudiometer. Close the two-way valve to the eudiometer. Record the starting volume level in Part II of the data table.
4. Mass a weighing dish to the nearest 0.1 gram.
5. Calculate the combined mass of the weighing dish and sodium bicarbonate needed.
6. Mass the proper amount of bicarbonate needed. Hint: If massing out a full mole, measure out a half mole twice. This will prevent solid from spilling all over the pan, etc.
7. Carefully add the massed solid to the Erlenmeyer flask. Tap the weighing dish so that any residual solid drops into the flask.
8. Add approximately 300 mL of water to the Erlenmeyer flask. Swirl. Observe whether the solid reacts with the water.
9. Tie a 12" cotton string around the lip of the 100-mL graduated cylinder with the plastic base and spout cut off.
10. Measure the volume of stock acid needed into a 150-mL beaker. Carefully transfer this acid into the 100-mL graduated cylinder with base and spout cut off. Pour in 5 mL extra to ensure a complete reaction.
11. Use the free end of the string to lower the graduated cylinder containing the measured volume of acid into the Erlenmeyer flask. Carefully, but securely, stopper the Erlenmeyer flask so that approximately 2" of the string is draped over the outside of the flask. When the flask is stoppered, the graduated cylinder should be hanging inside the flask. The size 10, one-hole stopper should contain the glass tubing connected to the plastic line going to the two-way valve, which is then connected to the eudiometer (see Figure 4). Do not allow the acid to spill out of the cylinder at this point.
12. Open the two-way valve so the gas that is formed in the Erlenmeyer flask can flow into the eudiometer and force the water out into the overflow tank. Warning: Make sure the stopper has been removed from the base of the eudiometer.
13. Slowly tip the Erlenmeyer flask so about 50 mL of the acid spills out of the graduated cylinder into the flask. The reaction will begin. As the gas replaces the water in the eudiometer, the eudiometer must be held down to prevent it from floating.
    • IMPORTANT: Never, Never, Never tip the flask so that the opening of the glass tubing at the top of the flask is submerged—even for an instant. If the opening does get submerged, the gas pressure in the flask can rapidly rise and force the stopper to fly out of the top of the flask.
    • The outflow rate of the gas can be regulated by the rate the acid is spilled out of the graduated cylinder onto the bottom of the flask. This spill rate is controlled by the angle that the flask is tipped as you hold it. Gradually introduce more acid from the cylinder into the flask allowing the reaction to occur on a steady, slow rate. A good flow rate is 2–3 liters of gas per minute.
14. When most of the sodium bicarbonate has reacted, swirl the flask so that all the solid comes in contact with the acid. Gradually let all the acid in the graduated cylinder spill out into the flask.
15. When swirling is no longer followed by bubbling, the reaction in the flask is complete. Measure the volume of gas collected in the eudiometer to the nearest 0.1 liter. Record the value in Part II of the data table.
16. Record the temperature of the gases in the eudiometer in Part II of the data table.
17. Convert the observed volume of gas collected under laboratory conditions to the volume that would exist under standard conditions by completing the data table and using the combined gas laws.
18. Compare the observed volume of CO₂ at STP to the theoretical volume and calculate the percent error.
19. Dismantle the eudiometer and drain the overflow tank.

Lab Demo 2: Converting One Mole of Liquid or Solid to One Mole of Gas

Setup of the Eudiometer

1. Prepare the ediometer as outlined in the Prelab Preparation (see Figure 5).
   {13884_Procedure_Figure_5}

Demonstration
Throughout this procedure, it will be necessary to record material weights and observations on the data and results table attached.

1. Weigh the clean, dry, 50-mL Erlenmeyer flask. Record in Part I of data table.
2. Calculate the theoretical combined mass of the 50-mL flask and one (1) mole, or simple fraction of one mole, of liquid nitrogen (or dry ice). Record in Part I of the data table.
3. Carefully insert a 3" length of glass tubing into the #1 one-hole stopper. 1" of tubing should extend above the stopper.
4. Connect the stopper to the plastic T connector with a 18" section of plastic tubing.
5. Check to make sure the rubber stopper fits correctly into the 50-mL flask (see Figure 6).
   {13884_Procedure_Figure_6}
6. Measure exactly one mole, or simple fraction of one mole, of liquid nitrogen (or dry ice) into the 50-mL flask as precisely as possible (using an electronic balance) and stopper the flask with the one-hole stopper connected to the balloon and eudiometer.

   Note: This part is tricky and requires some practice. Tips to help are as follows: Wear protective insulating gloves and goggles. Fill a small Styrofoam^® cup (creased to form a small spout) about ⅔ full with liquid nitrogen. Pour the liquid nitrogen from the cup into the flask. Pour about 5.0 g more than necessary. Watch the balance closely as the liquid rapidly boils off. Be ready to stopper the flask immediately when the correct mass of liquid remains in the flask.
   Note: Dry ice (solid carbon dioxide) may be used in place of liquid nitrogen. Grind the dry ice into small granules using a mortar and pestle. Then use either a spatula or a creased square of paper to place the solid in the 50-mL Erlenmeyer flask. Put in about 0.5 g more than necessary. Watch the balance closely as the solid sublimes. Be ready to stopper the flask immediately when one (1) mole of solid remains in the flask. Place the flask on a hot plate and heat gently to aid in the sublimation process.

7. At this point, as the liquid nitrogen continues to boil (the dry ice sublimes), the balloon will expand to allow for the increasing amount of nitrogen gas (or carbon dioxide). Open the valve immediately to allow the gas to flow to the mole eudiometer. As the gas flows to the mole eudiometer, water will be forced out of the eudiometer chamber. As the gas replaces the water in the eudiometer, the eudiometer must be held down to prevent it from floating.
8. If the flask becomes too cold and the boiling rate slows, gently swirl the flask.
9. When the transition in the flask is complete, measure the volume of gas collected in the eudiometer to the nearest 0.1 liter. Record in Part II of the data table.
10. Measure the temperature of the gas in the eudiometer to the nearest 0.1 °C. Record in Part II of the data table.
11. Determine the current barometric pressure and enter the data in Part II of the data table. (Reading may be obtained from your school barometer or, if one is not available, contact your local weather bureau.)
12. Measure the temperature of the water in the overflow tank and record it in Part II of the data table. Enter vapor pressure of water at this temperature from the reference table in Part II of the data table.

Lab Demo 3: The Reaction of an Active Metal With an Acid

Setup of the Eudiometer

1. Prepare the ediometer as outlined in the Prelab Preparation (see Figure 5).
   {13884_Procedure_Figure_5}

Part I. Preparation of the Reactants

1. Determine whether you will use one-half mole or some simple fraction of one-half mole of active metal. Do not use more than one-half mole of the active metal. Record in Part I of data table.
2. Calculate the mass of metal needed. Record in the data table.
3. Mass a small weighing dish to the 0.1 g. Record in the data table.
4. Calculate the combined mass of the weighing dish and the active metal needed. Record in the data table.
5. Mass the active metal turnings in the weighing dish on the pan of a balance until the mass is equivalent to the combined amount calculated above. Do not use metal powder; use metal turnings.
6. Carefully add all the massed metal to the Erlenmeyer flask. Tap the weighing dish so any residual solid drops into the flask.
7. Add approximately 300 mL of water to a Erlenmeyer flask.
8. The molarity of concentrated hydrochloric acid is 12 M. Record this value in the data table.
9. Write the chemical equation for the reaction to be run. Enter the required data in the data table.
10. Determine the moles of acid needed to react completely with the number of moles of metal being used. Refer to the balanced chemical equation for this reaction. Record in the data table. (Remember: Use only one-half mole or less of the active metal.)
11. Calculate the volume of stock solution that contains the number of moles of acid needed. Record in the data table.
12. Tie a 12" cotton string around the lip of a 100-mL graduated cylinder with the plastic base and spout cut off (see Preparation of Acid Cylinder).
13. Measure out the volume of acid solution, calculated in step 11, into a 150-mL beaker. Add 5 mL more to ensure a complete reaction.
14. Carefully add the acid in the beaker to the specially modified plastic graduated cylinder.
15. Carefully, by holding the string, lower the graduated cylinder containing the acid into the Erlenmeyer flask. At this point, do not allow the acid to spill into the flask.
16. Carefully, but securely, stopper the Erlenmeyer flask so that approximately 2" of the string are draped over the outside of the flask. When the flask is stoppered, the graduated cylinder should be hanging inside the flask. The size #10 one-hole stopper used should be connected to the plastic line going to the eudiometer.

Part II. Running the Reaction and the Volume of the Gas That Is Produced

1. Open the stopcock so the gas that is formed can flow into the eudiometer and force the water out into the overflow tank. Again make sure the stopper has been removed from the base of the eudiometer.
2. Important: This reaction is highly exothermic. As the reaction takes place, the flask must be cooled in a bucket (or other vessel) containing ice water.
3. Slowly tip the Erlenmeyer flask so some (about 30 mL) of the acid spills out of the graduated cylinder and onto the metal and water. The reaction will begin. As the gas replaces the water in the eudiometer, the eudiometer must be held down to prevent it from floating..
   1. IMPORTANT: Never, Never, Never tip the flask so that the opening of the glass tubing at the top of the flask is submerged—even for an instant. If the opening does get submerged, the gas pressure in the flask can rapidly rise and force the stopper to fly out of the top of the flask.
   2. The outflow rate of the gas can be regulated by the rate that acid is spilled out of the graduated cylinder into the flask. This spill rate is controlled by the angle that you tip the flask as you hold it. Gradually introduce more acid from the cylinder into the flask allowing the reaction to occur at a steady, slower rate. A good flow rate is 2–3 liters of gas per minute. Remember to cool the flask in an ice/water bath.
4. When most of the active metal has reacted, allow any remaining acid in the cylinder to spill out into the flask. Swirl the flask so that all the solid comes in contact with the acid. When no solid remains in the flask, the reaction is complete.
5. Measure the volume of gas collected in the eudiometer to the nearest 0.1 liter. Record in Part II of the data table.
6. Measure the temperature of the gas collected in the eudiometer. Record results in the data table.
7. Determine current barometric pressure and enter the data in the data table. (Reading may be obtained from your school barometer or, if one is not available, contact your local weather bureau.)
8. Measure the temperature of the water in the overflow tank and record in the data table. Enter vapor pressure of water at this temperature in Part II. (Refer to reference table).
9. Convert the observed volume of gas collected under laboratory conditions to the volume that would exist under standard conditions by completing the data table and using the combined gas laws

Student Worksheet PDF

13884_Student1.pdf

Teacher Tips

• For Lab Demo 1, be sure to use care and proper technique when inserting the glass tubing into the one-hole rubber stoppers.
• We cannot stress enough to use the balloon to handle the excess pressure and be sure the two-way valve is open to prevent any buildup of pressure in the system.
• If an acid other than 12 M HCl is used, calculate the required volume of acid needed using the formula:
  {13884_Tips_Equation_8}
• The data sheet can be made into an overhead to enlist the students in the predemonstration calculations.
• A submergible pump (from an old aquarium) can greatly facilitate the emptying of the eudiometer and overflow tank.
• If the eudiometer leaks air slightly from the top, a light coating of stopcock grease can restore the seal.
• Ideally, the final water level in the eudiometer will be the same as the water level in the overflow tank. Any difference in levels will result in a pressure differential and must be taken into account.
• For Lab Demo 2, liquid nitrogen is often available from local welding supply firms. Consult your local telephone directory.
• Dry ice is often available at ice cream stores, especially before Halloween.
• Be sure to use care and proper technique when inserting the glass tubing into the one-hole rubber stoppers.
• We cannot stress enough to use the balloon to handle the excess pressure and be sure the two-way valve is open to prevent any buildup of pressure in the system.
• The data sheet can be made into an overhead to enlist the students in the predemonstration calculations.
• A submergible pump (from an old aquarium) can greatly facilitate the emptying of the eudiometer and overflow tank.
• If the eudiometer leaks air slightly from the top, a light coating of stopcock grease can restore the seal.
• Ideally, the final water level in the eudiometer will be the same as the water level in the overflow tank. Any difference in levels will result in a pressure differential and must be taken into account.
• For Lab Demo 3, Magnesium or aluminum metal with concentrated hydrochloric acid works very well for this demonstration. Sample chemical equations:

  Mg(s) + 2HCl(aq) —> H₂(g) + MgCl₂(aq)
  Al(s) + 3HCl(aq) —> 3/2H₂(g) + AlCl₃(aq)

• The active metal is the limiting reagent and the acid is in excess.
• Be sure to use care and proper technique when inserting the glass tubing into the one-hole rubber stoppers.
• We cannot stress enough to use the balloon to handle the excess pressure and be sure the two-way valve is open to prevent any buildup of pressure in the system.
• If an acid other than 12 M HCl is used, calculate the required volume of acid needed using the formula:
  {13884_Tips_Equation_9}
  The data sheet can be made into an overhead to enlist the students in the predemonstration calculations.
• A submergible pump (from an old aquarium) can greatly facilitate the emptying of the eudiometer and overflow tank.
• If the eudiometer leaks air slightly from the top, a light coating of stopcock grease can restore the seal.
• Ideally, the final water level in the eudiometer will be the same as the water level in the overflow tank. Any difference in levels will result in a pressure differential and must be taken into account.

Sample Data

Lab Demo 1: The Reaction of a Bicarbonate With an Acid

Part I: The Reactants

1. Number of moles of sodium bicarbonate 0.5 mole
2. Mass of sodium bicarbonate 42.00 grams
3. Molarity of the acid solution used 12 M
4. Moles of acid needed to react with all the moles 0.5 moles of sodium bicarbonate being used (Write the balanced chemical equation.) 
5. Volume of acid solution needed (milliliters) 42 milliliters

Part II: The Volume of the Gas That Is Produced

1. Volume of gas collected under lab conditions 12.5 liters (V₁)
   1. Starting volume 22.0 liters
   2. Final volume 9.5 liters
2. 1. Temperature of the gas collected (Celsius) 23.7 °C
   2. Temperature of the gas collected (Kelvin = °C + 273) 296.8 K (T₁)
3. 1. Pressure of the atmosphere (inches of Hg) 30.3 inches of Hg
   2. Pressure of the atmosphere (mm = in x 25.4 mm/in) 769 mm of Hg
4. 1. Temperature of the water in the eudiometer 23.7 °C
   2. Vapor pressure of water at this temperature 21.1 mm of Hg (Refer to the Table 1.)
5. Pressure of the dry gas collected 748 mm of Hg (P₁)

Convert the observed volume of the dry gas in the eudiometer to the volume under standard conditions (STP).

6. Volume of carbon dioxide gas collected under standard conditions (STP) (6) 11.3 liters (V₂)
7. Moles of carbon dioxide gas expected (7) 0.5 moles (See the balanced chemical equation.)
8. Volume of carbon dioxide gas at STP, theoretical (8) 11.2 liters
9. Percent error (9) 1 %
   {13884_Data_Table_1_Vapor Pressure of Water at Different Temperatures}

Lab Demo 2: Converting One Mole of Liquid or Solid to One Mole of Gas

Part I: The Starting Material

1. 1. Name of the substance used dry ice (solid CO₂)
   2. Chemical formula of the substance used CO₂
2. 1. Initial physical state gas
   2. Probable initial temperature of the substance used –78.5 °C
3. Number of moles of the substance that you will use 1 mole
4. Mass of the substance needed 44.0 grams
5. Mass of 50-mL Erlenmeyer flask 42.6 grams
6. Mass of 50-mL Erlenmeyer flask + mass of solid or liquid sample needed 86.8 grams

Part II: The Volume of the Gas That Is Produced

1. Name of the gas produced carbon dioxide
   
2. Chemical formula of the gas that is produced CO₂
   
3. Volume of the gas collected under lab conditions 25.1 liters (V₁)
4. 1. Temperature of the CO₂ gas collected (Celsius) 25.0 °C
   2. Temperature of the CO₂ gas collected (K = 273 + °C) 298 K (T₁)
5. 1. Pressure of the atmosphere (inches of Hg) 30.3 inches of Hg
   2. Pressure of the atmosphere (mm = in x 25.4 mm/in) 769 mm of Hg
6. 1. Temperature of the water in the overflow tank 25.0 °C
   2. Vapor pressure of water at this temperature 22.5 mm of Hg (Refer to the Table 1.)
7. Pressure of the dry CO₂ gas collected 747 mm of Hg (P₁)

Convert the observed volume of the dry gas in the eudiometer to the volume under standard conditions (STP).

8. Volume of the gas collected under standard conditions 22.6 liters (V₂)
9. Moles of gas expected 1 mole
10. Volume of gas at STP expected 22.4 liters
11. Percent error 0.9 %
    {13884_Data_Table_1_Vapor Pressure of Water at Different Temperatures}

Lab Demo 3: The Reaction of an Active Metal With an Acid

Part I: The Reactants

1. Number of moles of metal 0.5 mole
2. Mass of active metal needed 12.2 grams
3. Mass of weighing dish 2.4 grams
4. Mass of weighing dish and active metal 14.6 grams
5. Molarity of the acid solution used 12 M
6. Moles of acid needed to react with the moles of metal being used 1 mole

   (Write the balanced chemical equation.) 2HCl + Mg —> MgCl₂ + H₂

7. Volume of acid solution needed (milliliters) 83.5 milliliters

Part II: The Volume of the Gas That Is Produced

1. Name of the gas produced hydrogen
2. Chemical formula of the gas that is produced H₂
3. Volume of gas collected under lab conditions 13.0 liters (V₁)
1. Temperature of the hydrogen gas collected (Celsius) 21.9 °C
2. Temperature of the hydrogen gas collected (Kelvin) 295 K (T₁)
4. 1. Pressure of the atmosphere (inches of Hg) 29.5 inches of Hg
   2. Pressure of the atmosphere (mm = in x 25.4 mm/in) 750 mm of Hg
5. 1. Temperature of the water in the overflow tank 22.0 °C
   2. Vapor pressure of water at this temperature 19.8 mm of Hg (Consult a reference book for this value.)
6. Pressure of the dry hydrogen gas collected 717 mm of Hg (P₁)

Convert the observed volume of the dry gas in the eudiometer to the volume under standard conditions (STP).

8. Volume of hydrogen gas collected under standard conditions (STP) 11.4 liters (V₂)
9. Moles of hydrogen gas expected (See the balanced chemical equation.) 1 mole
10. Volume of hydrogen gas at STP expected 11.2 liters
11. Percent error 1.8%