1. A 334 mL cylinder contains 5.225 g of Helium at 23 °C. How many grams of He m

Question

1. A 334 mL cylinder contains 5.225 g of Helium at 23 °C. How many grams of He must be released to reduce the pressure to 75 atm? (Show all work.)

2. Place the following gases in order of increasing average speed at 25 °C: Ne, HBr, SO2, NF3, CO, He.

3. Suppose 120.0 kg of N2 is stored in a 1100.0 L metal cylinder at 280 °C. Calculate the pressure inside the canister assuming all of the liquid nitrogen vaporizes using both the ideal gas equation and the Van deer Waals equation. If the storage tank is rate to 180 atm, will the canister rupture when solving using the two methods? (Show all work.)

4. Arrange the following intermolecular forces in order of increasing strength. (Hydrogen bonding, DipoleDipole, IonDipole, London Dispersion Forces, and Ionic Bond)

5. Which of the two molecules, propane (C3H8) or heptane (C7H16), would have a

a. Greater London Dispersion Forces  

b. Lower boiling point  

c. Greater viscosity

6. Explain why water’s boiling point is over 100°C higher than the heaviest molecule from the same column such as H2S (60.0°C), H2Se (41.3°C), and H2Te (2.2°C) using intermolecular forces.

7. Use the ClausiusClapeyron equation to determine the enthalpy of vaporization using the data below. An experiment was preformed to determine that a certain liquid has a vapor pressure of 13.95 torr at 25.0°C and 144.78 torr at 75.0°C. (Hint: Remember to change the temperature to Kelvin.)

Explanation / Answer

Answer 1) P V =n*R*T

T= 273.15 +23 = 296.15 K

75 atm * 0.334 L =n* 0.0821 l atm/ * mol K * 296.15

n= 1.030 moles

amount of He = no of moles * molar mass of He = 1.030 mole * 4 g/mole = 4.12 g

so the amount of He releses = 5.225 -4.12= 1.105 gram

Answer 2)

Always remember the smaller the molar mass, more will be the speed
molar mass of species are Ne 20.1 g/mol, HBr 81 g/mol ,SO2,64g/mol , NF3, 71g/mol ,CO. 28 g/mol

so the speed in the increasing average order is
HBr < NF3 < SO2 < CO < Ne

4) Hydrogen bonding, DipoleDipole, IonDipole, London Dispersion Forces, and Ionic Bond

the inceasing order is

  London Dispersion Forces<Hydrogen bonding<IonDipole,<Ionic Bond

Answer 5)

Greater london dispersion force = heptane(C7H16)

lower boiling point = propane (C3H8)

Greater viscocity = heptane(C7H16)

Answer 6) why water’s boiling point is over 100°C higher than the heaviest molecule from the same column such as H2S (60.0°C), H2Se (41.3°C), and H2Te (2.2°C) using intermolecular forces.because only water has the capability to form intermolecular hydrogen bonding due to which its boiling point further increases upto 100 Co .

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