Can somneone please help with this Chem problem PLEEEEEEEEEASE! Thanks!?

Question

Would someone please explain this Chem prob.?
What is the new temp. in degrees C?
Solve for the new temperature in degrees C when the following pressure changes occur, with constant n and V:

a) A 10.0-L container of helium gas with a pressure of 250 torr at 0 degrees C is heated to give a pressure of 1500 torr.

b) A sample of air at 40 degrees C and 740 mm Hg is cooled to give a pressure of 680 mm Hg.



Please explain the work, Thanks!

Answer 1

Use this relationship: P1T2 = P2T1 aka Gay- Lassac law.
a)
P1 = 250 torr
T2 = ?
P2 = 1500 torr
T1 = 273 K
T2 = (P2T1)/P1 = 1638 K = 1365 C

b)
P1 = 740 mmHg
T2 = ?
P2 = 680 mmHg
T1 = 273 + 40 = 313K
T2 = (P2T1)/P1 = 288K = 15 C

In both cases you are solving for the second temperature. If you have trouble with formulas, review your math a bit. Remember to always convert from C to K when doing gas problems.

Dox GAS law = Do not eat chili and drink beer before a big date. ;o}

Answer 2

Answers:
(a) 1365.75 degree Celsius
(b) 14.6 degree Celsius


The SOLUTION:

Using the ideal gas equation,

PV = nRT

if n and V were to be held as constants, and of course, R is also a constant (the gas constant), we will be left with:

P = kT

or

P/T = k


If we use ratio and proportion between the two given values, we will get:

P1 / T1 = P2 / T2

Remember that the temperature should be represented in Kelvin Scale, so we need to convert the given temperatures from Celsius to Kelvin.

Kelvin = Celsius + 273.15


Thus, we can solve for (a) as follows:

(a) Given: P1 = 250 torr
P2 = 1500 torr
T1 = 0 degree Celsius --> 273.15 Kelvin (K)

Find: T2 = ?

From P1 / T1 = P2 / T2, we can re-arrange the equation into:

T2 = (P2 * T1) / P1

Hence, if we substitute the values we have for P1, P2, and T1, we get:

T2 = (1500 torr * 273.15 K) / 250 torr

.:. T2 = 1638.9 K

But the question asks us to give the answer in Celsius unit, so we just subtract 273.15 from it using this equation:

Celsius = Kelvin - 273.15

.:. T2 = 1365.75 degree Celsius


The same process is used in solving for (b). Try it.

(b) Given: P1 = 740 mmHg
P2 = 680 mmHg
T1 = 40 degree Celsius --> 313.15 K

Find: T2 = ? (REMEMBER: the question asks us to give the answer in Celsius unit, not just in Kelvin, okay?)

God bless! =)