# I submitted these figure and my professor told me they were wrong I don't know who else to figure it.

Submitted by kodihansen on Sat, 08/17/2013 - 14:45

Experiment 10 Assignment

 A.Room temperature 294.6 K B.Mass of Zinc used .25 mL C.Volume of 6M HCl used 10 mL D.Final temperature 285.2 K E.Final pressure 1.68 atm

 Results Calculation Description A.Moles of Zn reacted 1 1 would be in front of Zn in the reaction B.Moles of H2 produced. (The balanced reaction for this experiment isZn + 2HCl àZnCl2 + H2 There is a 1:1 ratio between moles of zinc and moles of H2, therefore the number of moles of Zn = moles of H2) 1 1 would be in front of H2 in the eqaution. C.Volume of gas collected at room temperature. [PV=nRT, R =0.08206 Latm/molK] D.Molar volume at room temperature (volume of gas collected at RT/moles of hydrogen) E.Molar volume at STP, use P1V1/T1 = P2V2/T2

Using the expected or accepted Molar Volume of H2 at STP (1atm, 273K), compare your results to the accepted value by calculating the percent error. Percent error = ((your value – accepted value)/accepted value) x 100

What gas laws did you use to complete the calculations of this experiment?

What do you feel is the largest source of experimental error in determining the molar volume at STP? If any.

What I learned by completing this experiment:

Print Lab Manual

Background

Robert Boyle found that, under isothermal conditions (constant temperature), the pressure of a gas is inversely proportional to its volume. This also means that the product of the pressure and volume is a constant. The equations that describe this relationship are:

P * V = constant

and

P1* V1= P2* V2

Jacques Charles found that the volume of a gas under isobaric conditions (constant pressure) is directly proportional to its temperature. As the temperature increases so does the volume that the gas occupies. The equations that describe this relationship are:

V / T= constant

and

V1/ T1= V2 / T2

It is possible to combine Boyle's law and Charles' law:

P1 * V1/ T1= P2* V2/ T2

The Ideal Gas Law includes the dependence of the volume on the number of gas moles, and an experimentally determined proportionality constant, called the Universal Gas Constant, which is designated by R.

The mathematical formulation of the law is written as follows:

(P * V) / (n * T) = R

or in the more familiar form:

P * V = n * R * T

The value for the Universal Gas Constant, R, is 0.0816 L atm/mol K.

One important result of the Ideal Gas Law is that under conditions of constant pressure and temperature, one mole of any gas will always occupy the same volume.

The volume that one mole of an ideal gas occupies when held at a specific temperature and pressure is referred to as a "molar volume". For example, at one atmosphere, the molar volume of any ideal gas is 22.414 L/mol at 0 �C and 24.137 L/mol at 21�C. Most gases follow the Ideal Gas Law closely at atmospheric pressure and room temperature.

In this experiment you will determine the molar volume of hydrogen gas and compare it with the value predicted by the Ideal Gas Law. Hydrogen gas is produced in the following reaction between zinc and hydrochloric acid:

Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)

One can calculate the molar volume of the gas at room temperature and pressure according to the equation:

Molar volume (L/mol) = (measured volume) / (number of moles)

To complete this lab you will need to: (1) Calculate the number of moles of H2produced (Hint: For every mole of zinc used in the reaction, one mole of H2is produced.). (2) Measure the volume of H2gas produced.

Procedures

1. Take an Erlenmeyer flask from the Containers shelf and place it on the workbench.

2. Add 10 mL of 6 M HCl solution from the Materials shelf to the Erlenmeyer flask.

3. Double-click on the Erlenmeyer flask and select "Close" to plug the flask with an air-tight stopper.

4. Take a thermometer and pressure gauge from the Instruments shelf and attach them directly to the flask. Change the units for the thermometer to K by clicking thermometer's unit button until K is displayed. Remember all gas work is done in Kelvin or K. Record the temperature which is room temperature. No need to record the pressure at this time. Note: The units on the pressure gauge should be changed to atm by clicking pressure gauge's unit button until atm is displayed below the readout. Remember atmospheres or atm are the units most commonly used in gas work.

5. Add 0.25 g of zinc (Zn) from the Materials shelf to the Erlenmeyer flask.

6. Watch for evidence of the reaction between the zinc and HCl (pay close attention to the mixture immediately after adding the zinc). Record all of the indications that the reaction has occurred in you Lab Notes.

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