Measuring the pressure of a gas

In summary, the conversation discusses the pressure difference in a tube, with one side containing water and the other containing gas. It is determined that the pressure difference is 1000 pascals, but there is a discrepancy in the calculation of the gas pressure. While one person argues that it should be 101,000 pascals (1000 pascals + atmospheric pressure), the other points out that atmospheric pressure is usually ignored when discussing gas pressure. In certain applications, however, it is necessary to use the absolute pressure, which includes atmospheric pressure.
  • #1
Steve143
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http://img526.imageshack.us/img526/8780/pressurew.jpg

I worked out that the pressure difference is 1000 pascals

For part b the book says the pressure of the gas is 1000 pascals but shouldn't it be 1000 pascals + 100,000 pascals (atmospheric pressure) making the pressure of the gas 101,000 pascals? because the water has atmospheric pressure on it from the left side of the tube and the gas is not only counteracting it but pushing the water too making me think it is pressure difference + atmospheric pressure. I can't think of a reason why atmospheric pressure would be ignored and it would be stated as 1000
 
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  • #2
When asked for the pressure it usually means the pressure disregarding atmospheric pressure. If atmospheric pressure is included it is called 'Absolute pressure' of the gas.
When dealing with the gas laws you must use the Absolute pressure.
So you are correct in some applications.
 
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FAQ: Measuring the pressure of a gas

What is the unit of measurement for gas pressure?

The unit of measurement for gas pressure is typically expressed in either Pascals (Pa) or atmospheres (atm).

How is gas pressure measured?

Gas pressure is typically measured using a device called a manometer, which consists of a U-shaped tube filled with a liquid, such as mercury or water. The gas is then introduced into one side of the tube, causing the liquid to move and creating a measurable pressure.

What factors affect gas pressure?

The main factors that affect gas pressure include temperature, volume, and the number of gas particles present. According to the ideal gas law, as temperature and volume increase, so does the pressure. Additionally, as the number of gas particles increases, the pressure also increases.

How is gas pressure related to altitude?

As altitude increases, the pressure of a gas decreases. This is because as altitude increases, there is less atmospheric pressure pushing down on the gas. This is why many people experience difficulty breathing at high altitudes, as there is less oxygen present due to the decrease in pressure.

What are some applications of measuring gas pressure?

Measuring gas pressure is important in various industries, such as in the production of food and beverages, in medical devices, and in monitoring gas pipelines for safety purposes. It is also used in everyday tasks like inflating car tires and checking the pressure of home appliances such as air conditioners.

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