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8/10/2019 disccusion

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Discussion

In experiment 1, we need to determine the relationship between pressure and volume

of an ideal gas based on Boyle Law. For this experiment, it can be divided into 3 difference

conditions. These conditions are, from pressured vessel to atmospheric pressure, from

atmospheric vessel to vacuum vessel and the last one is from pressured vessel to vacuum

vessel. The Boyles Law is verified in condition 1 because the difference between PV

before and after is only 0.013105.According to Boyles law, relationship between the

absolute pressure and volume of a gas is inversely proportional, if the temperature is kept

constant within a closed system. Thus, the results above proved the Boyles Law. As a

precaution for this part is we need to make sure the pump presser lever did not exceed 2 bar

as excessive pressure may result in glass cylinder breaking.

Then, in experiment 2 we need to determine the relationship between pressure and

temperature of an ideal gas based on Gay-Lussac Law. The experiment was conducted by

using 6 difference pressure started from 110 kPa abs to 160 kPa abs. Then, the average

temperature was obtained from 3 trials. The graph of Pressure against Temperature was

plotted to determine the patent of the gradient line. Based on the graph obtained,the pressure

is directly proportional the temperature. Hence, the Gay-Lussac law is verified. As a

precaution for this part is we need to make sure the pump presser lever did not exceed 2 bar

as excessive pressure may result in glass cylinder breaking.

Next, in experiment 3 we need to demonstrate the isentropic expansion process.

Isentropic expansion is a process of heat capacity of an ideal gas at constant volume and

pressure. It can be expressed as pVk= constant, p2V2k= p2V2

k. In isentropic process, there is

no heat loss or transferred and not even transformation could occur. The value of k is 1.4.In

this experiment, the value is 0.8820. There are some slightly difference between these two

values which is 0.73%. The expansion process was proven as isentropic.


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Then, experiment 4 is about Stepwise Depressurization. In this experiment, we need

to study the response of the pressurized vessel following stepwise depressurization. The valve

was opened until the pressure in the chamber is back to the atmospheric pressure which is

somewhere around 101.32 kPa. The depressurization shown that pressure decrease with time

and also affecting the temperature. As the pressure decrease, the temperature also decrease

in the system.

Next, experiment 5 is about Brief depressurization. The objective of the experiment is

to study the response of the pressurized vessel following a brief depressurization. During

this experiment, we need to connect the hose from compressive pump to pressurised

chamber before switch on the compressive pump and allow the pressure inside chamber to

increase until about 160kPa. The pump was switch off and the hose from the chamber was

removed. The pressure reading was recoded. Its started from150.3 kPa and ended at 138.8

kPa.The graph plotted in result section shown that it is decrease more linear compared to

stepwise. The expansion occur when the pressure of gas increase. Expansion of gas decrease

as the gas is free to flow out time by time.

In experiment 6 we need to determine the ratio of volume and compare it to the

theoretical value. For this experiment, it is same as at experiment 1 which is need to do for 3

conditions. These conditions are from pressured vessel to atmospheric pressure, from

atmospheric vessel to vacuum vessel and the last one is from pressured vessel to vacuum

vessel. The reading of pressures needs to be recorded before and after. By using the

formula,Volume1/Volume2 = (P2 final-P2 initial)/ (P1 initial-P1 final), we determine that

the difference before and after is 0.098 only.


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