CHEM 1001/CHM 1020/ Chm1025C/CHM1032C         Name:__Answers

Module 6 SamplePretest

Module Six Part E Gas Law Problems                            35 points

Boyle’s Law

1.  A sample of a gas has a volume of 100 mL when measured at 25 oC and

760 mmHg.  What volume will the gas occupy at 25 oC and 380 mmHg?

V1P1=V2P2

100 mL      X        760 mmHg      =      200 mL  (answer)

1                      380 mmHg

Charles Law

2. The volume of a gas is 100.0 mL at 27 oC.  At what temperature in degrees Celsius would the volume of the gas be 200.0 mL, assuming the pressure remains constant.

V1  =  V2                V2 T1__      =     T2

T1      T2                    V1

200.0 mL x 300 K    =   600 K (answer)

100.0 mL

Dalton’s Law of Partial Pressures

3. The volume of hydrogen collected over water is 100 mL at 25 oC and 763.8 torre.  Calculate the dry volume in milliliters of 200 mL of hydrogen gas collected over water at 25 oC at 760 torre pressure with the temperature remaining constant.  (The partial pressure of water vapor at 25 oC is 23.8 torre.)

Ptotal =  PH2 dry  + PH2O         PH2 dry  =  760 torre – 23.8 torre  =  736.2 torre

V1P1=V2P2

200 mL  x   736.2 torre       =   193.7 mL (Answer)

760 torre

Gay-Lussac’s Law

4.  A sample of gas occupies 100.0 L at 710.0 torre and 27 oC.  Calculate the pressure in torre if the temperature is changed to 127 oC , while the volume remains constant.

P1  =  P2                P1 T2__      =     P2

T1      T2                    T1

710.0 torre x 400 K    =   946.7 torre (answer)

300 K

Avogadro’s Law

5.   A 1.5 mole sample of a gas occupies 25.0 L at 758 torre and 27oC. Calculate the Volume of the gas, if more molecules are injected into the vessel increasing the moles to 2.5 moles, provided the pressure and the temperature do not change.

V1  =  V2                V1 n2__      =     V2

n1      n2                    n1

25.0 L x 2.5 mol    =   41.7 L (answer)

1.5 mol

Ideal Gas Equation-Combined Gas Laws

6. Calculate the number of moles of nitrogen gas in a 5.00 L cylinder at 27 oC and 4 atm pressure. R = 0.0821 L atm/ K mole )

PV = nRT

4 atm x 5.00 L                            =    0.813 mol

300 K  x 0.08205 L atm/Kmol

How much does this volume of gas weigh?

.813 mol x 28.0 g/mol = 22.8 g (answer)

Corwin 7th Paper and Pencil Homework:

Boyles Law:               Questions 15-20 p 307-8

Charles Law:              Questions 21-26 p 308

Gay-Lussac’s Law     Questions27-32 p308

Combined Gas Law:  Questions 33-42 p 308

Dalton’s  Law:            Questions 47-54 p 308

Ideal Gas Behavior and Gas Law:      Questions 55-66 p 308-9