The general gas equation was deprived from______?

Analyze the question: The question asks which laws were combined to give the general gas equation, PV/T = constant (the combined gas law). The word "deprived" is a typo for "derived".

Explain the concept:

• Boyle's law: At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure: V ∝ 1/P.
• Charles' law: At constant pressure, the volume of a fixed mass of gas is directly proportional to its absolute temperature: V ∝ T.

Step-by-step solution:

1. Combine the two proportionalities for a fixed mass of gas: V ∝ 1/P (Boyle) and V ∝ T (Charles)

2. Together they give: V ∝ T/P

3. Introduce a constant of proportionality: PV/T = constant

4. For a gas changing from one state to another: P₁V₁/T₁ = P₂V₂/T₂

5. For one mole of gas the constant is R, and for n moles: PV = nRT (the general gas equation)

Checking the options:

• A. Gay-Lussac's law (pressure law, P ∝ T) is also a gas law, but the standard derivation uses Boyle's and Charles' laws. Option A is therefore not the best answer.
• B. Graham's law concerns the rate of diffusion, so it is not involved.
• C. Boyle's and Charles' laws is correct.
• D. Dalton's atomic theory is about atoms, not gas behavior.

Exam tip: Remember "Boyle + Charles = general gas equation". Boyle gives the pressure-volume link and Charles gives the volume-temperature link, and combining them gives PV/T = constant.