# When doing calculations, should pressure be in atm or Pa?

• Lee
In summary, when doing calculations involving pressure and energy (in joules), it is recommended to use Pascals for pressure, volume in cubic meters, and the universal gas constant R = 8.3145 J mol^-1 K^-1. This ensures consistency and simplifies the calculations.
Lee
When doing calculations, should pressure be in atm or Pa? (looking for answers in joules)

Doesn't matter AFAIK as long as you adjust the constants for example R in PV=nRT.

Good'o. I just wanted to double check.

Use Pascals. P = F / A, Force is usually given in Newtons amd 1 Pa = 1 Nm^-2.

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all you need is to have is consistant units.
pressure in Pa, volume in cubic meters and R = 8.3145 J mol^-1 K^-1
then work will be in joules

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Always choose the path with the least number of conversions.

Daniel.

## 1. What is the difference between atm and Pa?

The unit atm (atmosphere) is a measurement of pressure commonly used in everyday contexts, while Pa (Pascal) is the standard unit of pressure in the International System of Units (SI). 1 atm is equal to 101,325 Pa.

## 2. When should I use atm and when should I use Pa?

Atm is typically used for low pressure measurements (e.g. atmospheric pressure) while Pa is used for higher pressure measurements (e.g. in laboratory experiments). It is important to use the appropriate unit depending on the scale of the pressure being measured.

## 3. Are there any other units of pressure besides atm and Pa?

Yes, there are many other units of pressure including bar, mmHg, and psi. However, atm and Pa are the most commonly used in scientific calculations.

## 4. How do I convert between atm and Pa?

To convert from atm to Pa, multiply the number of atm by 101,325. To convert from Pa to atm, divide the number of Pa by 101,325.

## 5. Is there a difference in accuracy between atm and Pa?

Atm and Pa are both accurate units of pressure, but Pa is considered to be more precise as it is the standard unit in scientific calculations. However, for most everyday purposes, the difference in accuracy between the two units is negligible.

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