CHEM 30A QUIZ 8 GASES NAME: Total 20 points Time 25 min PLEASE SHOW ALL WORKING

Question

CHEM 30A QUIZ 8 GASES NAME: Total 20 points Time 25 min PLEASE SHOW ALL WORKING FOR FULL POINTS. Use bathroom and phones before the start of the test. Piease sit on assigned seats 1) A 5.00-L tank contains helium gas at 1.50 atm. What is the pressure of the gas in torr? A) 1.50 tor B) 507 torr C) 760 torr D) 1140 torr E)75 torr 2) At constant temperature, a sample of helium at 760 torr in a closed container was compressed from 5.00 L to 3.00 L, with no change in moles or temperature. What was the new pressure exerted by the helium on its container? A) 800. torr B) 2280 tor C) 15.0 torr D) 3800 torr E) 1220 torT Answer 3)The volume of a gas with an initial pressure of 380 mmHg atm increases from 5.0 L to 80 L what is the final pressure of the gas.in atm, assuming no change in moles or temperature? A) 238 atm B) 2.4 atm C) 0.31 at D) 0.80 atm E) 8.0 atm Answer 4) The temperature of a 500 mL sample of gs froan 150. K to 350. K. What is the final volume of the sample of gas, if the pressure and moles in te bsioer is A) 210 ml B) 1170 mL C) 0.0095 ml D) 00470 mL E) 110. mL Answer hept coestant? 5) A gas at 5.00 atm pressure was stored in a tank during the winter at 50 "C. During the summer, the emperature in the storage area reached 40.0 C What was the pressure in the gas tank then? A) 0.625 atm B) 4.44 atm C) 5.63 atm D) 40.0 atm E) 69.5 at Answer

Explanation / Answer

1. 1 atm = 760 torr

    therefore by coverting the 1.5 atm in torr , we get

     = 1.5 x 760 torr

     = 1140 torr

answer = 1140 torr

2. According the question the moles and temperature are constant

therefore by ideal gas law eqaution

~ PV=nRT

~   PV = Constant

therefore , P1V1 = P2V2

P1 = initial pressure

P2 = final pressure

V1= initial volume

V2 = final volume

putting the values we get,

~ 760 x 5 = P2 x 3

~ P2 = 1270 torr (approx)

3.

By ideal gas law eqaution

~ PV=nRT

According to the qst,

~   PV = Constant

therefore , P1V1 = P2V2

~ 380 x 5 = P2 x 8

~ P2 = 237.5 torr

by converting it into atm we get

1 torr = 1/760 atm

therefore ; 237.5 torr = 237.5/760 atm

hence answer = 0.31 atm

4. By ideal gas law eqaution

~ PV=nRT

According to the qst,

~   V is directy proportional to T

~ V ~ T

~ V= kT

~ V1/T1 =V2/T2

hence putting the values

= 500/150 = V2/350

Answer - V2 = 1170 ml

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