Absolute Pressure, Boyle's and Pascal's

The gauge pressure inside a container is 53,000 Pa. Calculate the absolute pressure in kPa.

(a)  

A machine has two dials. The first one gives a pressure reading of 55 kPa gauge, and the second has a reading of 115 kPa abs. Which of the following best describes the pressure readings?

• The first reading is higher than the second reading

  55 + 101.3 = 156.3

  is greater than 115

• The second reading is higher than the first reading

  115 is greater than 55

• The first reading is less than the second reading

  55 + 14.7 = 71.7 is less than 115

• The first reading is higher than the second reading

  55 is less than

  115 + 101.3

A machine has two dials. The first one gives a pressure reading of 5 psig, and the second reads 11 psia. Which of the following best describes the pressure readings?

• The first reading is higher than the second reading

  5 + 14.7 = 19.7 psi

  is greater than 11 psi

• The first reading is higher than the second reading

  11 psi is greater than 5 psi

• Both readings are equal because both measure pressure

• None of the readings is correct

Which best describes Boyle’s law? (Pick 3)

Absolute pressure refers to

• a. the pressure measured by a pressure gauge plus the atmospheric pressure.

• b. the pressure measured by a pressure gauge minus the atmospheric pressure.

• c. the highest pressure that a component can withstand.

• d. the pressure measured by a Bourdon tube pressure gauge.

A gas is initially at an absolute pressure of 400 kPa. If its volume doubles, what is its ultimate absolute pressure? Presume that the atmospheric pressure is 101.3 kPa.

• 800 kPa

• 200 kPa

• 100 kPa

• None of the above

A gas is initially at a gauge reading of 400 kPa. If its volume doubles, what is its ultimate absolute pressure? Presume that the atmospheric pressure is 101.3 kPa.

• 901.3 kPa

• 301.3 kPa

• 100 kPa

• 200 kPa

A 500 mL gas at 2 atm pressure is compressed to 250 mL. What is the new pressure of the gas?

• 1 atm

• 2 atm

• 4 atm

• 8 atm

Given a constant temperature, if you start with a gas at 100 kPa and 50 L, and then compress the gas to 25 L, what will be the new pressure?

• 50 kPa

• 100 kPa

• 200 kPa

• 400 kPa

The picture shows two completely identical mason jars. They're both filled with the same gas, only one of them has more in it (more molecules). What can you say about the pressures of both jars?

• P₁ > P₂ (greater pressure in jar 1)

• P₁< P₂ (greater pressure in jar 2)

• P₁ = P₂ (same pressure in both)

• There's not enough info to tell