PART A: BOYLE’S LAW

Data Processing:

X: If the height of mercury in opened end tube is higher than the closed end tube.

Y: If the height of mercury in opened end tube is lower than the closed end tube.

Volume of gas = Height of gasVg = hg

Pressure of gas = PP = Px

= Patm – Phg

= Patm + (Px1 – Px2)Volume of gas = Height of gasV = hg

= k – x2

Pressure of gas = PP = Py

= Patm – Phg

= Patm – (Py1 – Py2)

Volume of gas = Height of gasV = hg

= k- y2

(Px1 – Px2) difference in height (Py1 – Py2)

P, pressure of gas

V, volume of gas

PV

0.00 72.915 16.8 1224.9720.90 73.815 18.0 1328.6701.70 74.615 18.3 1365.4554.90 68.015 15.2 1033.8287.10 65.815 15.4 1013.551

From the above data, two sets of graphs can be obtained. The first graph is the plot of P versus V; the second is the plot of P versus 1/V

Conclusion:From the results obtained, it is concluded that pressure decreases as the volume increases, at constant temperature.

Discussion:1. Since the diameter of the tube is assumed to be constant, the volume of gas

sample ≡ height of gas column.

2. The apparatus used by Boyle in this experiment was very simple. The pressure exerted on the gas by the mercury level is adjusted so that the level is equally the same in both of the tube hand. Thus it is equal to the atmospheric pressure. Note that the tube is open at the top and it is therefore exposed to atmospheric pressure. As the opened end tube is moved further up, there is an increase in the pressure on the gas sample. This subsequently decreases the volume occupied by the gas. By moving up the opened end further (which increases the pressure), the volume occupied by the gas sample continues to decrease.

3. The shape of the graph for the P versus V should be of a half-meniscus line approaching V (X-axis) but the graph obtained was not perfect due to certain errors and limitation occurred while undergoing the experiment. To overcome the problems many improvements can be adapted.

P versus V

21

21.5

22

22.5

23

23.5

24.5 25 25.5 26 26.5 27

V

P

P versus 1/V

0

5

10

15

20

25

30

0 0.01 0.02 0.03 0.04 0.05

1/V

P

Evaluation:

Limitation RecommendationWhile conducting the experiment the closed end tube is not really air tight causes leakage to happen. Thus the experiment results are not accurate.

Fold the rubber tube that needs to be screwed. Instead of that, put any other thing at the end of the rubber tube in order to decrease chances for outside air from getting into the tube.

The ruler provided was not in the good condition as there was certain figure that has already disappeared.

Replaced the traditional wooden ruler with the latest one that made from plastic or metal. It is more practical as they are in the good condition. Hence better result can be obtained.

PART B: CHARLES’ LAW

Data Processing:

Source Temperature, T (ºC) Height, h (mm) T + 273.15 V/TIce + methanol

28.0 80.0 301.2 0.266

Ice Water10.1 74.0 283.3 0.261

Pipe water50.0 87.0 323.2 0.269

Warm water27.0 79.0 300.2 0.263

Conclusion:1. From the result obtained we can conclude that volume is proportional to the

temperature, the pressure being a constant.2. The absolute zero from the graph is -270 ºC.

Discussion:1. The diameter of the tube is assumed to be a constant, therefore the relation

between them are volume of gas sample ≡ height of the column.

2. The absolute zero is theoretically the lowest temperature achievable, which is -273.15ºC. The absolute zero is the starting point of the Kelvin temperature scale, K.

3. The absolute zero value is not accurately obtained to be -273.15 ºC, but is instead -270.0 ºC. This is caused by certain errors and limitations that occurred while doing the experiment. Many improvements can be adapted to the experiment to overcome the problems.

Evaluation:

Limitation RecommendationWhile measuring the height of gas, the glass tube has to be taken out from the solution. This might cause changes of the height as the temperature changed and will result to an inaccurate result

Carry out the procedure by taking the reading as soon as the glass tube is taken out from the solution. Avoid any possible delay while taking the readings.

It is impossible to keep the temperature maintained while the mercury plug is still moving using the manual method, especially for temperatures that are higher than room temperature.

Use the electronic water bath to for the temperatures that are higher than room temperature rather than using manual water bath. It is because the temperature is digitally controlled and maintained by electronic device. The accuracy is higher.

PART C: IDEAL GAS LAW

Data Processing:

Measurements ReadingsMass of flask + foil + rubber band 67.2117 ± 0.0001 gMass of flask + foil + rubber band + condensate

67.3627 ± 0.0001 g

Mass of condensate, m 0.1510 ± 0.0001 gTemperature of boiling water, T 100.00 ± 0.1ºCBarometer reading, P 72.915 ± 0.001 cm HgVolume of the flask, V 105 ± 1 ml

In order to calculate the RMM of the unknown, the ideal gas equation can be used which is as below:

and it is known that ,

Manipulation of the equation gives:

Where: P = Pressure, atm

V = volume, dm3

m = the mass, gM = molar massR = the molar gas constant; 0.082 atmdm3 K-1 mol-1 or 8.314 JK-1 mol-1

T = temperature, K

† Before substituting the values, they must be converted to the proper units of measurement first. The table below shows the conversion of the values:

Old Unit Value New Unit Value T = 100 ºC + 273.15 T = 373.15 K

P = 0.9594 atm

V = 0.105 dm3

The RMM is;

= (0.510g)(0.082atm dm 3 K -1 mol -1 )(373K) (0.9544atm)(0.105dm3)

P = 72.915cmHg x 1atm 76cmHg

V = 105cm 3 x 1dm3 1000

Conclusion:

The RMM of the unknown can be found by using the ideal gas law equation. Therefore the relative molecular mass for the unknown is 45.847g mole-1. The unknown substance is predicted to be ethanol (46.02g mole-1).

Discussion:

The ideal gas equation shows the relationship among the four variables P (pressure), V (volume), T (temperature) and n (number of moles). An ideal gas is a theoretical gas of which the pressure-volume-temperature behaviour can be completely accounted for by the equation. The molecules of an ideal gas do not attract or repel each other, and their volume is small (often negligible) compared to the volume of the container. Though ideal gas does not occur practically, discrepancies in the behaviour of real gases over a reasonable temperature and pressure ranges do not affect calculations.

The unknown substance is identified as ethanol.