If measurements of a gas are 50L and 300 kilopascals and then the gas is measured a second time and found to be 75L, describe what had to happen to the pressure (if temperature remained constant). Include which law supports this observation.

Question

If measurements of a gas are 50L and 300 kilopascals and then the gas is measured a second time and found to be 75L, describe what had to happen to the pressure (if temperature remained constant).  Include which law supports this observation.

needhelpp101 · Answer

@LaurenRoberts

anonymous · Answer

Calculate the new pressure with 
P1V1 = P2V2 
The pressure had to decrease if the volume increased. See Boyle's Law

anonymous · Answer

volume goes up, pressure goes up too

anonymous · Answer

If the volume increased, the other value will increase too.

jaynator495 · Answer

Explosive Diarrhea x100

needhelpp101 · Answer

HAHA @Jaynator495   OMG  >.<

needhelpp101 · Answer

@LaurenRoberts  Pressure had to decrease in order for the volume to increase.
The important thing to notice here is that temperature is being kept constant.
Assuming that the amount of gas you have remains constant as well, i.e. you don't add or remove gas from the container, then you can use the ideal gas law equation to write
P1⋅V1=n⋅R⋅T → for the first measurement
P2⋅V2=n⋅R⋅T → for the second measurement
If you replace the product n⋅R⋅T, which will be constant, in one of these two equations you'll get
P1⋅V1=P2⋅V2

This is the mathematical expression for Boyle's Law, which states that pressure and volume have an inverse relationship when temperature and number of moles (amount of gas) are key constant.
An inverse relationship means that if one increases, the other must decrease and vice versa.
Even before doing any calculations, you can use Boyle's Law to predict what will happen to the pressure. If volume increased from 50 to 75 L, then the pressure mush have decreased proportionally.
You can confirm this by
P2=V1V2⋅P2
P2=50L75L⋅300 kPa=200 kPa
The pressure indeed decreased, which corresponds to the increase in volume.
So, as a conclusion, when the temperature of the gas is constant, i.e. the average kinetic energy of the gas molecules remains unchanged, the volume the gas occupies can only increase if pressure decreases.
Likewise, the pressure of the gas can only decrease if the volume of the gas is increased.

jaynator495 · Answer

I normally dont come in math, but when i do... it tends to be for random reasons >_>

needhelpp101 · Answer

hehe

jaynator495 · Answer

I normally dont come in math, but when i do... it tends to be for random reasons >_>

jtfan2000 · Answer

Charles law - volume/temp both increase because they are related