# Finding temperature through a manometer

• Twoism
In summary, the mercury manometer attached to a gas cell shows a drop in mercury height from 120 mm to 30 mm when placed in an industrial freezer. This indicates a decrease in pressure, assuming the volume remains constant. The initial temperature is assumed to be 0C due to being in an ice-water mixture. Further information is needed to find the pressure of the system.
Twoism

## Homework Statement

The mercury manometer shown in the figure is attached to a gas cell. The mercury height h is 120 mm when the cell is placed in an ice-water mixture. The mercury height drops to 30 mm when the device is carried into an industrial freezer. HINT: The right tube of the manometer is much narrower than the left tube. What reasonable assumption can you make about the gas volume?
[PLAIN]http://img36.imageshack.us/img36/6331/knightfigure1650.jpg
I'm assuming the temperature is originally at 0C since it says it's in an ice-water mixture. I'm also assuming pressure is constant throughout the problem.

V/T=V/T
C+273=K

## The Attempt at a Solution

I attempted to do:
120/273K = 90/T
T=-68.25C
Wrong answer. I'm guessing there's more to put into the volume part of the equation than just the height, but I don't know exactly what. Can anyone help? Thanks.

Last edited by a moderator:
After much observation, I was wrong to conclude pressure would be the same. After reading the hint carefully, I came to the conclusion pressure changes, while volume remains constant. Still, I don't know how to find the pressure of the system.

p1*v1/t1=p2*v2/t2

Last edited:

## 1. What is a manometer?

A manometer is a scientific instrument that is used to measure the pressure of a gas or liquid in a closed container. It consists of a U-shaped tube filled with a liquid, usually mercury or water, and a scale to measure the difference in height between the two sides of the tube.

## 2. How does a manometer measure temperature?

A manometer does not directly measure temperature. However, it can indirectly measure temperature by using the ideal gas law, which states that the pressure and volume of a gas are directly proportional to its temperature. By measuring the pressure of a gas with a manometer, the temperature of the gas can be calculated.

## 3. What is the process of finding temperature through a manometer?

The process involves setting up the manometer, measuring the pressure of the gas, and then using the ideal gas law to calculate the temperature. This can be done by equating the pressure measured by the manometer to the product of the gas constant, the temperature, and the number of moles of gas present.

## 4. What are the advantages of using a manometer to find temperature?

One advantage of using a manometer is that it is a simple and relatively inexpensive instrument. It also allows for indirect measurement of temperature without having to come into direct contact with the gas being measured. Additionally, manometers can be used to measure a wide range of pressures, making them versatile in various scientific experiments.

## 5. Are there any limitations to using a manometer to find temperature?

Yes, there are some limitations to using a manometer to find temperature. One limitation is that it can only measure the pressure of a gas in a closed container, so it cannot be used for gases in open environments. Additionally, the accuracy of the temperature measurement may be affected by factors such as the type of liquid used in the manometer and external factors like air temperature and humidity.

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