Anyone good at chemistry?

Question

Can anyone help me? The volume of 400 mL of chlorine gas at 400 mm is decreased to 200 mL at constant temperature. What is the new gas pressure?

Why is the answer 800 mm Hg?

Answer 1

This uses the p1v1=p2v2 relationship, if you decrease the original volume by half, then you have to double the original pressure. You have the right answer.

Answer 2

This is just an example of the gas law called Boyle's law.

pressure x volume = constant

when temperature does not vary


For your problem:

400 mL x 400 mm Hg = 160,000

200 mL x ? mm Hg = 160,000

160,000 / 200 = 800 mm Hg



There are actually three named gas laws:

Boyle's law (1662, relating pressure and volume)
Charles's law (1787, relating volume and temperature)
Gay-Lussac's law (1809, relating pressure and temperature)

but they were a lot of trouble to remember separately, and were all combined into the "ideal gas law" that is:

PV = nRT


There is an ideal gas law calculator at:

http://www.chemicool.com/idealgas.html

Answer 3

Boyle's Law states that under conditions of constant temperature and quantity, there is an inverse relationship between the volume and pressure for an ideal gas.

based on the problem.,
we have..
P1 = 400 mm
V1 = 400 mL
V2 = 200 mL
P2 = ?

following the LAW., we come up wid d formula..
P1V1 = P2V2

we're looking for P2., we have..
P2 = (P1V1)/V2

substituting the values..
P2 = (400mL)(400mm)/200mL
= 800mm

therefore., the answer's correct!

Answer 4

If u decrease volume,pressure get high. Let's see what happens calculating the difference of pressure:


P= nRT/V

n and T are the same so we can say that:

PV=P'V'

we have to transform ml in L coz in equation for perfect gas u must use L so:

400ml=0.4 L

so:

400*0.4= 0.2*x

x= 800mmHg

Answer 5

Pressure and volume are said to be inversely proportional - as one goes down, the other goes up in proportion, and vice versa. So if the volume is halved, the pressure must double.