Experiment 7: Gas Law Goals 1. Students will understand the ideal gas law

2. Students will understand partial pressure 3. Students will understand limiting reagents

Objectives:

1. Students will be able to determine the identity of an unknown metal

2. Students will be able to use a gas collection tube

3. Students will be able to safely handle chemicals

4. Students will be able to do limiting reagent stoichiometry calculations

Introduction :

In this experiment you will be determining the identity of an unknown metal by determining the atomic mass and comparing your experimental results with the expected value. Obtaining accurate results will require taking a number of corrections into account.

Equipment:

1. Barometer (on the front wall)

2. Gas measuring tube (x8)

3. Buret Stand (x4)

4. Scissors

5. Thermometer, 0.1o C (x4)

6. 2-hole rubber stopper, #0 (x8)

7. Bucket

8. Universal pH paper

*Reagents:

1. Metal ribbon

2. Steel wool

3. 12 M HCl

4. Copper wire

5. Sodium bicarbonate

Resources:

1. http://science.widener.edu/svb/video/

2. CRC Handbook of Chemistry and Physics – You may use any edition

3. NIOSH Pocket Guide to Chemical Hazards (NPG) – http://www.cdc.gov/niosh/npg/

4. SIRI MSDS Database – http://siri.org/msds/index.php

5. NIST Fundamental Constants – http://physics.nist.gov/cuu/

6. Comprehensive Guide to Chemical Resistant Best Gloves – http://www.chemrest.com/ Widener University Chem 147 Page 46 5/18/2017

7. 12 Principles of Green Chemistry – http://bit.ly/1zV7h5c

8. Wikipedia – Eudiometer – http://en.wikipedia.org/wiki/Eudiometer

Procedure

1. Safety. Prior to working in the lab, you need to research physical properties, health and safety information for copper, water, hydrochloric acid and hydrogen. Check the material data safety sheet (MSDS), the NIOSH “Pocket Guide to Chemical Hazards” and “International Chemical Safety Cards”. Find the following information and give references: (a. CAS number b. Relevant physical properties c. NFPA code and meaning d. Necessary precautions)

2. Determination of atomic mass. Develop a procedure for determining the atomic mass. You can start with a piece of metal ribbon. If you add this to concentrated hydrochloric acid the ribbon will react and produce hydrogen gas. Details that you need to account for include:

a. Write the balanced chemical equation with phase designations for the reaction of the metal with hydrochloric acid. The metal will have a charge of +1, +2, +3, or +4.

b. How can you determine that the reaction has gone to completion?

c. Most metals react with oxygen in the air to produce oxides. What problem could this cause? How can you fix or avoid this problem?

d. Use 5-10 mL of HCl. It is important that the metal is the limiting reagent, how will you know if all the metal has reacted? For your first trial, start with 0.05 g of metal and adjust the mass accordingly based on the volume of gas produced.

e. Determine the vapor pressure of water for the conditions of this experiment. Prepare a graph of vapor pressure vs temperature for water. What information do you need to record during the experiment to use this graph to determine the vapor pressure of water?

f. How does the difference between the level of the water inside the gas collection tube and the level of water outside the gas collection tube affect the volume reading? What can you do to fix or avoid this problem and obtain the correct volume of gas?

g. Technique is important to getting good results. How many trials are you going to perform to get good experimental results?

h. The waste will be very acidic and contain excess HCl. How can you neutralize this prior to disposal? What does your experimental procedure need to include to address Green principal #1, Prevention?

3. Your procedure should include step-by-step detail for the following:

a. A balanced chemical equation with phase designations.

b. A consideration of all questions listed above for the determination of R.

c. Detail on what substances you use, the quantities you use and how you measure them, what glassware you use, etc.

d. A graph of vapor pressure vs temperature for water.

e. Numbered references for all external information you use.

f. Safety and waste disposal information.

g. Detail should be sufficient for another student to reproduce your experiment using nothing but your procedure.

Notes:

1- It must have all the steps.

2- All data should be recorded.

3- I will upload my previous procedure from exp.6 to show you how I need the work to be like!

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