# Answer to Question #56046 in General Chemistry for sue

Question #56046

Calculate the final pressure, in atmospheres, for each of the following with n and V constant.

Part A

A gas with an initial pressure of 1.20 atm at 87 ∘C is cooled to -50 ∘C.

Express your answer to two significant figures and include the appropriate units.

P = ???

Part B

A sample of N2 with an initial pressure of 780 mmHg at -50 ∘C is heated to 30 ∘C.

Express your answer to two significant figures and include the appropriate units.

P=???

Part A

A gas with an initial pressure of 1.20 atm at 87 ∘C is cooled to -50 ∘C.

Express your answer to two significant figures and include the appropriate units.

P = ???

Part B

A sample of N2 with an initial pressure of 780 mmHg at -50 ∘C is heated to 30 ∘C.

Express your answer to two significant figures and include the appropriate units.

P=???

Expert's answer

Part A The final pressure can be calculated using the formula of Gay-Lussac’s gas law converting the values of temperature to SI units T1 = 360.15 K; T2 = 223.15 K;

P2=T2P1/T1

P2 = 223.15x1.20/360.15 = 0.744 atm OR 121590 Pa

Part B. Using the same law and the values to the SI units

P1 = 103991 Pa; T2 = 303.15 K; T1 = 223.15 K;

P2 = 303.15x103991/223.15 = 141273 Pa

Answer: 121590 Pa; 141273 Pa

P2=T2P1/T1

P2 = 223.15x1.20/360.15 = 0.744 atm OR 121590 Pa

Part B. Using the same law and the values to the SI units

P1 = 103991 Pa; T2 = 303.15 K; T1 = 223.15 K;

P2 = 303.15x103991/223.15 = 141273 Pa

Answer: 121590 Pa; 141273 Pa

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