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# A question on Boyle's Law and Charles's Law?

I know that boyle said. Pressure X Volume = CONSTANT

and charles said. Volume/Temperature= CONSTANT

My question:

are they always the same constant?

### 3 Answers

- denwel33Lv 51 decade agoFavorite Answer
When considered separately, the two laws have different constants.

For Boyle's Law, the constant is the absolute temperature of the gas.

For Charles' Law, the constant is the absolute pressure of the gas.

Neither one of these is included in the equation for each law, because, due to being constant, they are not really necessary. For Boyle's Law, the equation is P1V1 = P2V2 (P being pressure and V being volume) and for Charles' Law, the equation is V1/T1 = V2/T2 (V being volume and T being temperature).

Due to being compatible with one another, the two laws can be combined to give a single equation that follows them both. When the two laws are combined, the constant of the resulting equation is divided by the number of moles of gas to give the Universal Gas Constant (R), which is equal to 8.31 J / K mol.

The resulting equation is pV = nRT

p = absolute pressure

V = volume of gas

T = absolute temperature

n = number of moles of gas

If the constant of the equation from the combined laws is divided by the actual number of molecules in the gas (N), you get Boltzmann's Constant (k), which is equal to 1.38 x 10^ -23 J / K.

The resulting equation in this case is pV = NkT.

- JoyceLv 44 years ago
The Kinetic Molecular theory of gasses states that 1)gasses are made up of particles moving constantly at random high speeds. 2) V is directly proptional to T :. The faster the gas particles move, the > Temp and > in Kinetic Energy 3) Particles are independant of each other 4) Particles are very far apart 5) Pressure is caused by impact of particles on the wall of a container. Boyles Law: P1V1=P2V2 therefore p and v are directly proportional. As the velocity increases the particles hit the side of the container faster :. P increases Charles Law: V is directly proportional to T so that is just the 2nd principle in the Kinetic Molecular theory so just reexplain it. Anyway im not gonna do the whole thing, but hopefully that will give you a starting point. Just Look at the equation and compare it to the info i gave you on the Kinetic Molecular theory. Goodluck. Msg back if you get stuck again

- Nick TLv 71 decade ago
Boyle's law describes the inversely proportional relationship between the absolute pressure and volume of a gas, if the temperature is kept constant within a closed system.

Charles's law states that at constant pressure, the volume of a given mass of an ideal gas increases or decreases by the same factor as its temperature on the absolute temperature scale (i.e. the gas expands as the temperature increases).