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Gas lawsChemistryHigh schoolabout 0:56

What is the pressure of 0.25 mol of gas in 2 L at 400 K?: animated lesson

A narrated, step-by-step gas laws video lesson with captions. Final answer: P = 4.10287 atm.

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Video with a synthetic English voice and captions. Pick another language for subtitles in that language, or open the interactive version.

Video narrated by a synthetic voice (Piper TTS, en_US-ljspeech-high voice (LJ Speech dataset, public domain)); the steps come from our maths engine and the answer was checked independently. Download MP4 (0.4 MB) · Captions (WebVTT)

Steps on screen

1. The problem
Worked example
What is the pressure of 0.25 mol of gas in 2 L at 400 K?
2. Step by step
1. $R = 0.082057366\ \text{L·atm/(mol·K)}$
  Choose the gas constant to match the units
2. $P = \frac{nRT}{V} = \frac{0.25 \times 0.082057366 \times 400}{2} = 4.10287\ \text{atm}$
  Rearrange PV = nRT for P and substitute
3. The answer
$P = 4.10287\ \text{atm}$
P = 4.10287 atm
4. Check
- PV = 8.20574 and nRT = 8.20574, which agree.

Transcript

The problem. Here is the problem: What is the pressure of 0.25 mol of gas in 2 L at 400 K? Solve PV equals nRT for P, with pressure in atm, volume in litres, amount in moles and temperature in kelvin.

Step by step. Choose the gas constant to match the units. Pressure is in atm and volume in litres. Rearrange PV equals nRT for P and substitute.

The answer. So the answer is P equals 4.10287 atm. An ideal gas obeys PV equals nRT: pressure times volume is proportional to the amount of gas and its absolute temperature. Real gases follow it closely at low pressure and high temperature.

Check. PV equals 8.20574 and nRT equals 8.20574, which agree.

About gas laws

Use the ideal gas law and the combined gas law to find pressure, volume, temperature or moles.

What is the pressure of 0.25 mol of gas in 2 L at 400 K?