Combined Law Calculator

Combined Gas Law:

\[ \frac{P1 \times V1}{T1} = \frac{P2 \times V2}{T2} \]

Initial Pressure (P1):

atm

Initial Volume (V1):

liters

Initial Temperature (T1):

Final Pressure (P2):

atm

Final Volume (V2):

liters

Final Temperature (T2):

Result:

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1. What is the Combined Gas Law?

The Combined Gas Law relates the pressure, volume, and temperature of a gas sample under different conditions. It combines Boyle's Law, Charles's Law, and Gay-Lussac's Law into one equation that describes how gases behave when pressure, volume, and temperature change.

2. How Does the Calculator Work?

The calculator uses the Combined Gas Law equation:

\[ \frac{P1 \times V1}{T1} = \frac{P2 \times V2}{T2} \]

Where:

\( P1 \) — Initial pressure (atm)
\( V1 \) — Initial volume (liters)
\( T1 \) — Initial temperature (Kelvin)
\( P2 \) — Final pressure (atm)
\( V2 \) — Final volume (liters)
\( T2 \) — Final temperature (Kelvin)

Explanation: The equation shows that the product of pressure and volume divided by temperature remains constant for a given amount of gas.

3. Importance of Combined Gas Law

Details: This law is essential for predicting how gases will behave under different conditions, with applications in chemistry, physics, engineering, and meteorology.

4. Using the Calculator

Tips: Enter any five known values (pressure in atm, volume in liters, temperature in Kelvin) and leave one field empty to calculate the unknown value. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: Why must temperature be in Kelvin?
A: The gas laws are derived using absolute temperature, where 0 K is absolute zero. Celsius or Fahrenheit scales have negative values which would give incorrect results.

Q2: When does the Combined Gas Law not apply?
A: It doesn't apply when the amount of gas changes (use Ideal Gas Law instead) or at very high pressures/low temperatures where real gas behavior deviates from ideal.

Q3: How do I convert Celsius to Kelvin?
A: Add 273.15 to the Celsius temperature. For example, 25°C = 298.15 K.

Q4: What are standard temperature and pressure (STP)?
A: STP is defined as 273.15 K (0°C) and 1 atm pressure, where 1 mole of ideal gas occupies 22.4 liters.

Q5: Can I use this for mixed units?
A: No, you must use consistent units (atm for pressure, liters for volume, Kelvin for temperature) for accurate results.