Given a barometric pressure of 751.5 mmHg , calculate the pressure of each gas sample as indicat

Given a barometric pressure of 751.5 mmHg , calculate the...

Key Concepts

Barometric Pressure

Barometric pressure is the pressure exerted by the Earth's atmosphere at a given point and is often measured in units such as millimeters of mercury (mmHg). It serves as a reference value for many applications, including calibrating instruments and correcting measurements taken in enclosed systems.

Manometer

A manometer is a device used to measure the pressure of gases or liquids by observing the displacement of a fluid column in a U-shaped tube or similar apparatus. It provides a direct way to compare the pressure of a gas sample to a known reference, such as atmospheric pressure.

Pressure Calculation in Gas Systems

Calculating the pressure of gas samples using a manometer involves combining the ambient, or barometric, pressure with any differences indicated by the manometer readings. This process requires accounting for the contributions of both the external atmospheric pressure and the fluid column height difference to obtain an accurate measurement of the gas pressure.

Transcript

00:01 Hi there.

00:02 In this problem, we are given a barometric pressure, or in other words, the pressure of the atmosphere is equal to 751 .5 millimeters of mercury.

00:21 And then we have two monometers.

00:24 We have part a, where we have a monometer, which is a curved tube, with the right side here being open to the atmosphere, and the left side.

00:43 Be in the bulb that contains our gas of interest.

00:47 And what we notice in our first one is that the level of the mercury is higher on the gas side and it's lower on the atmosphere side.

01:01 So this is all our mercury in here.

01:04 So let's think about what that means.

01:07 Think about these two forces pushing down.

01:09 The gas is pushing down.

01:11 The atmosphere is pushing down.

01:12 The atmosphere is winning the contest.

01:15 It's pushing down harder than the gases.

01:19 How much harder is the measurement? so the difference between this point and this point, it looks to me like it is just past one point, it's just past one, both directions.

01:33 So i'm saying it's going from 1 .1 in the one direction to 1 .1 in the other direction.

01:39 Or in other words, i'm going to say the difference is 2 .2 centimeters.

01:44 Right? so we have a difference of 2 .1.

01:47 2 .2 centimeters and from the picture we know the atmosphere is pushing down harder.

01:54 So the atmosphere has a pressure of 751 .5 and we want to know the pressure of the gas on the left side.

02:06 Well if the difference is 2 .2 centimeters, i'm going to multiply that times 10 to change it to millimeters.

02:13 That is going to be a difference of 22 millimeters of hg.

02:19 The question is whether the gas has that much less pressure or that much more pressure.

02:25 Well, since we determine that the atmosphere must be pushing down harder for the gas to be farther up or for the mercury to be further up on the gas side, we're going to have to subtract this 22.

02:38 And when we do that, we get 729 .5 millimeters of 8 .3 .5.

02:45 G as the pressure of the gas in this first monometer...

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