# Temperature Increase & Moles

• jimmy42
In summary, the ideal gas equation, n = PV/RT, shows that if everything else is equal and temperature rises, there will be fewer moles of gas. This is because n is inversely proportional to T, not directly proportional. To keep the pressure and volume constant while increasing temperature, some gas must be removed from the system. This can be understood through Avogadro's law, which relates volume and moles, and can be used to understand Boyle's and Charles's laws.

#### jimmy42

I have the variation of the ideal gas equation:

n = PV/RT

Assuming that everything else is equal and only temperature rises that will mean there are more moles than before. Is that right? How can that be?

Thanks for clearing it up.

First of all - you got it wrong, if everything stays constant and temperature goes up, n must go down. n is inversely, not directly proportional to T.

If the system is closed, and n is constant, heating the gas will mean pressure goes up. What can you do to lower the pressure?

Actually it means there will be fewer moles than before, because your formula says you are dividing by T not multiplying by it.

The only way you can keep the pressure and the volume both the same, and increase the temperature, is to remove some of the gas from the system. Think about what Boyle's and Charles's laws say about gases.

OK, thanks. I somehow forgot to do that, yes the pressure will go up.

If the system is closed, and n is constant, heating the gas will mean pressure goes up. What can you do to lower the pressure?

Reduce n?

jimmy42 said:
Reduce n?

Exactly. You have to OPEN the system and change it.

AlephZero said:
Actually it means there will be fewer moles than before, because your formula says you are dividing by T not multiplying by it.

The only way you can keep the pressure and the volume both the same, and increase the temperature, is to remove some of the gas from the system. Think about what Boyle's and Charles's laws say about gases.

Boyle's and Charles's law don't tell anything about n
its Avogadro's law relating V and n
with this you can relate all others!

## What is the relationship between temperature increase and moles?

The relationship between temperature increase and moles is governed by the ideal gas law, which states that the volume of a gas is directly proportional to the number of moles present and the temperature in Kelvin. This means that as the temperature increases, the volume of a gas also increases, assuming the number of moles and pressure remain constant.

## How does temperature affect the number of moles of a gas?

Temperature does not directly affect the number of moles of a gas. However, an increase in temperature can cause a gas to expand, leading to a decrease in the number of moles per unit volume. This is known as the molar concentration, which remains constant as long as the number of moles and volume are directly proportional.

## What is the significance of measuring temperature and moles in a chemical reaction?

Measuring temperature and moles in a chemical reaction allows scientists to accurately determine the amount of heat released or absorbed during the reaction. This is important in understanding the thermodynamics of a reaction and predicting its feasibility and efficiency.

## How does temperature increase affect the rate of a chemical reaction involving moles?

An increase in temperature can lead to an increase in the rate of a chemical reaction involving moles. This is because an increase in temperature provides more energy for the molecules to collide and react, leading to a higher frequency of successful collisions and a faster reaction rate.

## Can temperature and moles affect the equilibrium of a chemical reaction?

Yes, temperature and moles can affect the equilibrium of a chemical reaction. According to Le Chatelier's principle, an increase in temperature can shift the equilibrium towards the endothermic direction, while an increase in moles can shift the equilibrium towards the side with fewer moles. This can lead to changes in the equilibrium constant and ultimately affect the position of equilibrium in a chemical reaction.