CHEM 1040L Lecture Notes - Lecture 12: Ideal Gas Law, Pressure Sensor

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copperfly323

1 Jun 2018

School

Department

Chemistry

Course

CHEM 1040L

Professor

Peter Padolik

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Experiment 12

Introduction

The objectives of Experiment Twelve are to demonstrate Boyle's Law by measuring the

pressure of gas (air) while varying volume, and to observe Aoto’s Law by measuring the

pressure of gas while varying the temperature in closed systems. This was accomplished by

using a syringe to create varying amounts of pressure. The MeasureNet system then recorded

the pressure as the volume was changed, as well as recording the temperature as the pressure

flask was submerged and cooled in water. The concepts that related to lecture included were

Boyle's Law, Charles' Law, and Dalton's Law. The techniques that related to lab included using a

stir plate, using the MeasureNet system to record pressure, volume, and temperature values,

measuring pressure with a pressure sensor, and creating pressure by using a syringe in a closed

system.

Experimental Procedure

The experimental procedure was downloaded and printed off of Chem21labs.com, titled

"Experiment Twelve: Behavior of Gases." It came from pages 12-6 through 12-9. The

procedures were followed exactly as they were stated in the handout.

Results

Atmospheric Pressure 758.4 atm

Questions

1. The graph was used to determine the Vtubing value because Vtubing on the graph is

the opposite sign of the equation's y-intercept, when using the graph plot of Vsyringe

vs. 1/Pair.

2. The plots generated by manipulating Pair and Vair that demonstrate Boyle's Law were

Pair vs. 1/ Vair and Vair vs. 1/Pair because the law state's that pressure and volume are

inversely proportional. This is show because the graph had the equation y=1637.6x+1E-

05, which is similar to x^-1.

3. Rearrangement of the Ideal Gas Law equals: P=nRT/V. The slope of the line of my

equation represents the multiplication of the "N, R, T". So therefore slope= nRT.

5. Grasping the barrel of the end of the syringe can influence the pressure measurements.

This is so because since there is a direct relationship between temperature and

pressure, temperature from your hand, holding it anywhere besides the base, can

cause the syringe to warm up, thus altering the pressure reading by increasing the

pressure.

6. The value of k= the y intercept Pair divided slope of Pair/Temp units. K was found to be

456.47. So, by adding 273.15K to Kappa to get the answer in Kelvins, you get

456.7+273.15=729.61K.

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Document Summary

The objectives of experiment twelve are to demonstrate boyle"s law by measuring the pressure of gas (air) while varying volume, and to observe a(cid:373)o(cid:374)to(cid:374)"s law by measuring the pressure of gas while varying the temperature in closed systems. This was accomplished by using a syringe to create varying amounts of pressure. The measurenet system then recorded the pressure as the volume was changed, as well as recording the temperature as the pressure flask was submerged and cooled in water. The concepts that related to lecture included were. The techniques that related to lab included using a stir plate, using the measurenet system to record pressure, volume, and temperature values, measuring pressure with a pressure sensor, and creating pressure by using a syringe in a closed system. The experimental procedure was downloaded and printed off of chem21labs. com, titled. The procedures were followed exactly as they were stated in the handout.

Related Questions

This is all in the context of a Gas Laws labratory involvingBoyle's Law and Amonton's Law:

For Boyle's Law the class used the Vernier pressure sensor todetermine the pressure of nine syringe readings, ranging from 60 to20 mL. With those values we multiplied the pressure by the Volume(total) for each reading and compared each to the averagecalculated K valule.

An example equation for a readings is as follows:

Volume syringe = 60mL, pressure (atm) = 1.206, Volume of smalltube (constant through the experiment, = 3.28),

Pressure (1.206atm) x Volume total (60+volume tube (3.28)) =64.444528.

Average value = 65.69823

(64.444528-65.69823)/65.69823 = -1.146

The -1.146 value is the change in percent from the calculatedvalue to the average.

For Amonton's Law, the apparatus was assembled to hold anErnlynmyer flask within a 1 L water bath that is gradually heatedto 80 degrees C. As the temperature increases, the class collectsthe pressure reading within the flask in incriments of 2 degrees soa graph can be contructed with pressure on its x axis andtemperature on the y. Once these points are plotted, the graph canbe extrapolated to determine a calculated estimate as to whatabsolute zero should be.

The trendline equation determined was y=.00423189x +.9022160.

Solving for zero, the absolute zero temperature is-214.1411048.

1. Is it necessary to know the volume of the apparatus in thispart of the experiment? Why or why not?

2. Ideally, what should happen to the pressure of a gas if theKelvin temperature is doubled?

3. Which technique, extrapolation or interpolation, is morereliable and why?

n this exercise, weighed samples of a solid unknown containing NaCl and NaHCO3 react with hydrochloric acid. The volume of the CO2 liberated by the reaction in the gas phase is measured with a gas collection syringe. From the volume we can calculate the number of moles of CO2 in the gas phase using the ideal gas approximation.

Since the CO2 is generated in an aqueous environment (aqueous HCl), some CO2 will dissolve in the liquid phase. The amount of CO2 dissolved in the liquid phase is computed using Henry's Law which requires knowing the partial pressure of CO2. As described in the exercise, this requires knowing the volume of the entire gas system ( VfTOT)

To insure that your answers agree with Mr. OSCER's, use the values in the below table for the basic constants required. .

	Value	Units
Ideal Gas Constant	0.0821	L-atm/mol K
Convert Celsius temperture to Kelvin	273.15	K
Atmospheric Pressure	760.0	Torr
Molar Mass of NaHCO3	84.01	g/mol
Henry's Law Constant for CO2 in water	3.2 X 10-2	mmol/mL-atm

The figure below illustrates the volumes that are designated by Vtube and Vsyr .

Note also that Vsyr = Vf â Vi .

The table below contains data collected for one run of the required reaction, where an unknown sample mixture containing some NaHCO3 is mixed with hydrochloric acid:

	Value	Units
Initial Weight of container (empty)	18.4395	g
Final Weight of container and unknown	18.6185	g
Volume of hydrochloric acid	10.0	mL
Volume of tube, V_tube (see Figure above)	92.3	mL
Initial volume of syringe (V_i)	5.0	mL
Final volume of syringe (V_f)	50.7	mL
Temperature	26.5	^oC
Atmospheric Pressure	764.4	Torr
Vapor Pressure of Water at 26.5 ^oC	25.8	Torr

Use this data to answer the following questions. The appropriate units are specified in the each question. Pay close attention to the number of significant figures in your answers.

weight of sample (g) mixture before the start of the reaction = .179 g. Volume of CO2 gas (mL) that is produced by the reaction and is now contained in the syringe= 45.7 mL

What mass (g) of NaHCO₃ was contained in the sample mixture that was mixed with HCl ?

Enter a numeric answer only, to the correct number of significant figures. Do not include units with your answer.

CHEM 1040L Lecture Notes - Lecture 12: Ideal Gas Law, Pressure Sensor

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