Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P,...

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Gases Unit 2

Transcript of Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P,...

Page 1: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Gases

Unit 2

Page 2: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas Law

Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T)

Relates: P, V, Twhen n is constant

Equation: P1V1 = P2V2

T1 T2

Page 3: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas Law

Has 3 variables and can also be used as any of the above minor gas laws

Suggestion:

Organize your info before you start!

Page 4: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas Law

Examples:

A gas has a volume of 800.0 mL at 23.00oC and 300.0 torr. What would the volume of the gas be at 227.0oC and 600.0 torr of pressure?

Page 5: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas Law

V1 = 800.0 mL

T1 = 23.00oC = 296 K

P1 = 300.0 torr

V2 = ? mL

T2 = 227.0oC = 500 K

P2 = 600.0 torr

Page 6: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas Law

P1V1 = P2V2

T1 T2

(300.0 torr)(800.0 mL) = (600.0 torr)(V2) 296 K 500 K810.811 = 1.20(V2) 1.20 1.20V2 = 675.7 mL

Page 7: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas LawA gas sample occupies 3.25 L at 24.5oC

and 350 kPa. Determine the temperature (in Celsius) at which the gas will occupy 4.25 L at 150 kPa.

V1 = 3.25 LT1 = 24.5oC = 297.5 KP1 = 350 kPaV2 = 4.25 LT2 = ? oCP2 = 150 kPa

Page 8: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas Law

P1V1 = P2V2

T1 T2

(350 kPa)(3.25 L) = (150 kPa)(4.25 L)297.5 K T2

3.82 = 637.5 1 T2

Cross multiply…

Page 9: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas Law

(3.82)(T2) = 637.5

3.82 3.82

T2 = 167 K

-273

T2 = -106oC

Page 10: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas Law0.73 L of nitrogen at STP is heated to

80.0oC and the volume is increased to 4.53 L. What is the new pressure in mm Hg?

V1 = 0.73 L

T1 = 273 K

P1 = 760 mm Hg

V2 = 4.53 L

T2 = 80.0oC = 353 K

P2 = ? mm Hg

Page 11: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas LawP1V1 = P2V2

T1 T2

(760 mm Hg)(0.73 L) = P2(4.53 L)

273 K 353 K2.03 = 0.0128(P2)

.0128 .0128P2 = 160 mm Hg

Page 12: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas LawIf a gas in a rigid container has a pressure of

1.75 atm at standard temperature, what is the new pressure when it is heated to 50.0oC?

P1 = 1.75 atm

T1 = 273 K

P2 = ? atm

T2 = 50.0oC = 323 K

V1 = V2

Page 13: Gases Unit 2. Combined Gas Law Combines the laws of Boyle (P,V), Charles (V, T), and Gay-Lussac (P, T) Relates: P, V, Twhen n is constant Equation:P 1.

Combined Gas Law

P1V1 = P2V2

T1 T2

(1.75 atm)(V) = (P2)(V) 273 K 323 K565.25(V) = (273)(P2)(V)273(V) 273(V)

P2 = 2.07 atm