AP chemistry final review

Which of the following would have a faster rate of effusion: 15g of Kr or 15g of N₂?

• Kyrpton
• Nitrogen
• Both would have the same rate of effusion

why would O₂ effuse faster than CO₂ in the same room

• because it has more energy

• because it has a smaller molar mass

• because oxygen has a higher temperature

• they will effuse the same because the temperature is fixed

24.1% of all the isotopes of a an element have a mass of 75.23 amu, 48.7% have a mass of 74.61 amu, and 27.2% have a mass of 75.20 amu.
What is the average mass of this element?

• 74.92 amu
• 24.97 amu
• 75.01 amu
• 74.51 amu

Nitrogen has three occurring isotopes: Nitrogen-13, Nitrogen-14, Nitrogen-15. Which isotope is the most abundant?

• Nitrogen-13
• Nitrogen-14
• Nitrogen-15
• Based on the information given, it cannot be determined

You have a gas that has a pressure of 2 ATM and a volume of 10L.  What would be the new volume if the pressure was changed to 1 ATM?

• 5 L
• 20 L
• It would stay at 10L
• 1 L

Acidic buffer is made up of

• weak acid and weak base
• weak acid and its conjugate salt
• weak acid and its conjugate base
• strong acid and its conjugate base

Which solution A and B of equal volume and concentration mixed together to form a buffer?

• Nitric acid and potassium hydroxide
• Nitric acid and potassium nitrate
• Propanoic acid and potassium hydroxide
• Propanoic acid and potassium propanoate

When making a buffer of pH = 5, acids with the following K_a values are available. Which would be the best acid to use?

• 1.8 x 10^-5
• 1.8 x 10^-8
• 4.9 x 10^-10
• 3.0 x 10^-8

A buffer has a pH of 4.85 and contains formic acid and potassium formate.  What can you conclude about the concentrations of the components of the buffer?  The K_a of formic acid is 1.8 x 10^-4.

• Formic acid > Potassium formate
• Formic acid < Potassium formate
• Formic acid = Potassium formate
  
• More information is needed to determine the relative concentrations

What is the pH of a buffer that is 0.08 M NaA and 0.1 HA. The Ka of HA = 1.0 x 10^-4.

• 2.16
• 3.91
• 4.00
• 4.10