IB INTERNAL ASSESMENT - CHEMISTRY LAB REPORT.

Objective:I. Investigating the effect of pressure on the volume of gas.

II. Investigating the effect of temperature on the volume of gas.III. Studying the ideal gas equation.

Apparatus:Ruler, opened end monometer, glass tube, thermometer, conical flask, beaker, mercury plug, retort stand, Bunsen burner.

Materials:Rubber band, aluminum foil, ice, water bath, anti bumping granule

Experiment 1 - Boyle’s Law

Hypothesis:The volume of gas is inversely proportional to its pressure.

Variables:I. Independent: The gas pressure

II. Dependent : reading of the ruler which represents the gas volumeIII. Constant: Temperature.

Result:Reading on the clip: 47.30 ± 0.05Reading where mercury of both opening has the same level: 34.00 ± 0.05Volume of gas under atmospheric pressure Patm: 13.30 ± 0.05

Mercury level in closed

end tube(mm) ± 0.5 mm

Mercury level in opened

end tube(mm) ± 0.5 mm

Difference in height =

P hg

Pressure of gas, P(P = Patm

+ P hg )

Height of gas ± 0.5

mm

Volume of gas ± 0.5

mm

PV

100.0 163.00 63 196 238.0 238.0 46648114.0 158.00 44 177 243.0 243.0 43011117.0 147.00 30 163 248.0 248.0 40424121.0 134.00 13 146 253.0 253.0 46938144.0 132.00 12 145 258.0 258.0 37410

*Assuming that the diameter of the tube is constant, then the volume of the gas directly proportional to the height of gas column.

Evaluation:The experiment shows the relationship between the pressure of the gas and its volume at constant temperature. According to Boyle’s Law, in a constant temperature, the volume of gas is inversely proportional to the applied pressure put on the gas.

V 1/PV = k/P (k is a constant)VP = k

Theoretically, when graph PV against V (volume) is plotted we should get constant graph or one straight line stretches through the y- axis. Unfortunately, this kind of graph fails to be obtained due to some limitations.

Experiment 2 - Charles’s Law.

Hypothesis:The volume of gas is directly proportional to its temperature.

Variables:I. Independent: The temperature of the environment

II. Dependent :Volume of the gasIII. Constant: Pressure of the gas.

Result:

Environment Temperature of the water,(T ºC) ± 0.5 ºC

Temperature of the water in Kelvin (T) , T= T ºC + 273.15

Height of the gas column ± 0.5 cm.

*Volume of gas.

Warm water 50.0 323.15 7.40 7.40Pipe water 29.0 302.15 6.70 6.70Water + Ice-water

6.0 279.5 6.20 6.20

Water + Ice-ethanol

-4.0 269.15 5.80 5.80

*Assuming that the diameter of the tube is constant, then the volume of the gas directly proportional to the height of gas column.

Evaluation:The experiment shows the relationship between the temperature of the gas and its volume at constant pressure. According to Charles’s Law, at a constant pressure, the volume of gas is inversely proportional to the absolute temperature of the gas.

V TV = kT (k is a constant)V/T = k

Theoretically, when graph Volume (V) against Absolute Temperature (K) is plotted we should get a liner graph with k (the constant) as a gradient of the graph. Unfortunately, this kind of graph fails to be obtained due to some limitations.

Experiment 3 - Ideal Gas Law

Results:Mass of the conical flask + foil + rubber band: 67.8405 ± 0.0001gMass of the conical flask + foil + rubber band + condensate: 67.9441 ± 0.0001gMass of condensate: 0.1036 ± 0.0001gTemperature of the boiling water: 97.0 ± 0.5 ºC Barometer reading:Volume of the conical flask (represents the volume of the condensate): 155 ± 0.5 ml

Based on Ideal gas equation:

PV = nRT

P= Pressure appliedV= Volume of the gasT= Absolute Temperature n = number of molR= Gas constant

We know that, mass /relative molecular mass = number of molm/M = n

Hence, PV = nRT PV = m RT M M= m RT PV

In this case,R: 8.134JK-1mol-1

P: 733mm Hg X 101.325 kPa 760mm Hg =97.7253 kPa

V: 155.0 cm3

1000 =0.155 dm3

T: 73.30 ºC + 273.15 =376.42 K

Relative molecular mass of unknown compound can be determined using this formula,

M= m RT PV =(0.1036 g)( 8.134JK -1 mol -1 )( 376.42 K) (97.7253 kPa)( 0.155 dm3)

=20.9 gram mol-1

Limitations and recommendations:

Limitations RecommendationsThe clip that is clipping the tube might not be air thigh

We can fold the tube several times and then clip it to ensure that it is air thigh

The ruler is not a perfect measurement instrument to measure the level of the mercury because it has large scales and uncertainties.

Replace ruler with other measurement instrument that has smaller scales and smaller uncertainties

The heat from our hand (generated by our body) might affect the results of the experiment when we hold the glass tube.

Avoid holding the glass tube using our hand.

When we took out the gas tube out of its environment to record the height of the gas column, the room temperature will affect the reading if we take too much time to determine the reading.

After we took out the gas tube out of its environment, we need to take the reading as fast as possible to avoid the room temperature from influents the reading.

The unequal distribution of heat wills influent the results.

We can stir the water slowly using a glass rod to distribute the heat in the water evenly.

Conclusion: The gas law is mathematically related to the temperature (T), pressure (P) and volume (V). The relationships are stated by Boyle’s Law, Charles Law and Ideal Gas Law.