How Does Heat Affect Pressure?

Question

Im in grade 8 so nothing to complicated

Answer 1

Here is my answer from a few weeks ago, to the same kind of question:

http://answers.yahoo.com/question/index;_ylt=AjLvQXOH0db6N3Vlx_xgGDnty6IX;_ylv=3?qid=20070914082628AAL3Eck&show=7#profile-info-04RhsFZqaa

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Answer 2

It is believed in classical physics that energy (heat in your case) affects the molecules by making them more active. This activity, from extra energy being added, causes the atoms to collide and bounce off of each other at a more rapid rate than the previous state of the system. When measured the heat can be tested with a thermometer and the pressure can be measured with a Gage.
If sufficient heat is added to a gas the energy can be measured by an increase in the pressure, if the gas is in a container that the physical volume can not change.

Answer 3

With regard to Gases, it's Gay Lussac's Law that's involved.
"At constant volume, the absolute pressure of a given mass of gas is directly proportional to its absolute temperature".

Basically, in a CLOSED system, gas pressure increases with increase in temperature and vice-versa. (if not enclosed, the gas will simply expand on heating or contract on cooling).
(As a matter of interest, the Temperature however MUST be in Absolute Units for accurate calculations when using the Gas Laws. For °C, it is changed to Kelvin units by adding 273 to the Celsius figure. (e.g. a gas temperature of 50°C = 50 + 273 = 323K. (K - 273 = °C).
(Should you be using Fahrenheit, then °F + 460 = Rankine absolute temperature (R).
(R - 460 = °F).

With liquids it's a different story. A completely LIQUID FULL, sealed container of liquid, when heated, will expand and, because liquids are incompressible, even a very small temperature increase will increase pressure dramatically and further temperatures increases can build up tremendous pressure...Not advisable.

Answer 4

If temp of a constant mass of gas increase the gas expands and if its volume is fixed ,I mean if it is placed in a closed container then expansion of the gas will cause the pressure to increase..

Answer 5

PV=nRT

Says it all!