# How Much Gas

Partner: Yuchen

Title: How Much Gas

CHM 151 LL

Wednesday: 11:15-2:00

Instructor: Dr. Leary

May 1, 2013

Introduction

In this project we will choose a solid reagent, Mg, CaCO3, or Na2CO3, to react with a hydrochloric acid solution, HCl. We are going to measure the amount of gaseous product obtained from the amount of gaseous product obtained from reaction. Then compare to theoretical yield, Percent Yield=Actual Yield of Gas/ Theoretical Yield of Gas×100, based on stoichiometric prediction. The Ideal Gas Law, PV=nRT, will be needed to calculate the mass of reactants and moles of gas produced. Where P is the pressure in atm, V is the volume in Liters, n is the number of moles, R is the constant 0.0821(atm*L/K*mok), and T is the temperature in Kelvins. In this lab the volume of reaction space needs to be measured. I have chosen to use Magnesium and the amount of H2 gas that the amount of magnesium, (.04g), used is 0.00229 mol H2.

Procedure

1. Fill a 125 mL flask with 50 mL of HCl (aq)

2. Obtain and set up the pressure sensor

3. Record intial temperature,( room temperature)

4. Take the initial pressure and make sure it’s constant for at least 10 seconds 5. Add Mg (s) to the HCl (aq) (use an amount between 0.2 g - 0.4 g) 6. Record the final pressure, until it plateaus

7. Repeat steps 1-6 two more time for a total of 3 trials

8. Measure the volume of the container holding the reaction

Observations, Data, and Results

| Trial 1| Trial 2| Trial 3|

Volume of HCL (mL)| 15 mL| 15 mL| 15 mL|

Mass of mg (g)| .04 g| .03 g| .032 g|

Minimum pressure (atm)| .9776 atm| .9966 atm| .9810 atm| Maximum pressure (atm)| 1.3346 atm| 1.3845 atm| 1.3550 atm|

Calculations

Balanced chemical equation

Mg (s) + 2HCI (aq) → MgCl2 (aq) + H2 (g)

Ideal gas equation

PV = nRT

P = 0.4 atm

V = volume of flask = 139 mL = 0.139 L

T = 23 ०C = 23 ०C + 273.15 = 296.15 K

Theoretical Yield

(0.4 atm)*(0.125 L) = n * (0.0821...

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