IB Chemistry 12

Pressure/Volume of Air Full Lab Write Up

Introduction:

According to Boyle’s Law, the volume of any given amount of gas held at a constant temperature varies inversely with the applied pressure. In other words, when the pressure increases the volume decreases. When pressure decreases, volume increases. This can be derived from the following equation: P1 V1=P2 V2

The common use of this equation is to predict how a change in pressure or volume will alter the volume/pressure of the gas. Thus, the product of the initial volume and pressure is equal to the product of pressure and volume after a change in either pressure or volume under constant temperature.

Aim:

In this experiment, we will investigate the relationship between the pressure and volume of air. My hypothesis is as we decrease the volume (press down on the syringe) then the pressure measured by the pressure gauge will increase.

Materials:

* Pressure gauge (kPa = ± 2.0) (mmHg = ± 10.0)

* Rubber stopper

* Extender

* Stopcock

* 60.0 mL Syringe (± 0.5)

Figure 1a Figure 1b

Procedure:

1. Obtain all required materials from the teacher.

2. Fill the syringe to its maximum measured capacity of air (60.0 mL ± 0.5) by gradually pulling the syringe extender away from the actual syringe. [See Figure 1a]. Next, carefully attach the syringe to the stopcock, extender, rubber stopper, and pressure gauge accordingly. [See Figure 1b] Make sure the stock cock is opened (test the stock cock and syringe head of time so you know that the left turn allows the air to flow though while the right turn closes the valve and doesn’t let air escape) so that the air from the syringe can enter through the extender to the pressure gauge. 3. Using the 60.0 mL ± 0.5 syringe, for the first trial carefully push the plunger down slightly to a lowered volume of 55.0 mL ± 0.5 and hold this position to record the pressure movement (the inner red numbers represent pressure in units of kilopascals, while the outer numbers in the black font are measured in mmHg or Mercury). 4. Repeat step 3, but instead of lowering the plunger to 55.0 mL ± 0.5, lower the plunger at a constant interval of 5 [so that the next data point is 50.0 mL ± 0.5, and the next 45.0 mL ± 0.5, 40.0 mL ± 0.5, 35.0 mL ± 0.5, 30.0 mL ± 0.5, 25.0 mL ± 0.5, 20.0 mL ± 0.5] each time accurately recording the pressure readings. 5. Graph and interpret data and the relationship between pressure and volume of air at room temperature.

Results:

Summary Data of Volume and Pressure of air (gaseous mixture that mostly includes nitrogen, oxygen, argon and carbon dioxide) at a constant room temperature of 21.0 ± 1.0˚C. Volume (mL) (± 0.5)| Pressure (mmHg) (± 10.0)| Pressure (kPa) (± 2.0)| 55.0| 90.5| 12.1|

50.0| 100.1| 13.3|

45.0| 110.0| 14.7|

40.0| 125.0| 16.7|

35.0| 145.0| 19.3|

30.0| 165.5| 22.1|

25.0| 200.0| 26.7|

20.0| 250.1| 33.3|

Data Summary of Pressure and Inverse Volume

1/Volume (1/mL) (±0.001)| Pressure x Volume (mmHg)| Pressure x Volume (kPa)| 0.018| 4977.5| 665.5|

0.020| 5005.0| 665.0|

0.022| 4950.0| 661.5|

0.025| 5000.0| 668.0|

0.029| 5075.0| 675.5|

0.033| 4965.0| 663.0|

0.040| 5000.0| 667.5|

0.050| 5002.0| 666.0|

Theoretical Pressure Calculations:

P1 V1=P2 V2

Using the equation P1 V1=P2 V2, I calculated the actual pressure (the value that I theoretically could produce) and compared it with my experimental value (what I measured during the experiment itself). Both sides of the equation must balance each other.

Trial 1:

P1 V1=P2 V2

(90.5 mmHg ± 10.0)(55.0 mL ± 0.5) = (P2) (50.0 mL ± 0.5)

P2 = 99.6 mmHg ± 10.0%

Trial 2:

(100.1 mmHg ± 10.0)(50.0 mL ± 0.5) = (P2) (45.0 mL ± 0.5) P2 = 111.2 mmHg ± 9.0%

Trial 3:

(110.0 mmHg ± 10.0)(45.0 mL ± 0.5) = (P2) (40.0 mL ± 0.5) P2 = 123.8 mmHg ± 8.1%

Trial 4:

(125.0...