Equilibrium & Solubility Flashcards Preview

MCAT Chemistry > Equilibrium & Solubility > Flashcards

Flashcards in Equilibrium & Solubility Deck (23):
1

Does a catalyst affect the reaction equilibrium?

Nope, it only affects the rate or reaction

2

Which physical states are not included when calculating equilibrium constant?

No liquids or solids

3

If the forward rate constant is 4x the reverse rate constant, what is K(eq) after a catalyst has been added that doubles the rate of the forward reaction?

CATALYST DO NOT AFFECT EQUILIBRIUM CONDITIONS!!
Catalysts lower the activation energy for the forward and reverse reaction, so the ratio of forward to reverse rate stays the same, so K(eq) stays the same. So K(eq) still equals 4.

4

Don't confuse reaction rate with rate constant!

Reaction rate = rate constant * [concentration]

5

When K>Q, which direction does the reaction proceed to reach equilibrium??

Right.
There is too much reactants and not enough products, that's why Q is smaller than K, so the reaction will proceed to the right.

6

When K

Left.
There is too much products and not enough reactants, that's why Q is bigger than K, so the reaction will proceed to the left.

7

Is the volume of a closed flask fixed or flexible?

Fixed because flasks are made of rigid material, so volume is fixed

8

Is the volume of a closed piston fixed or flexible?

Flexible because the wall of the piston is free to move so the volume can vary

9

Why is acid rain so bad?

It dissolves basic salts a lot more than water, because basic salts like magnesium hydroxide have reduced solubility water due to common ion effect

10

Basic salts are most soluble in what kind of solution?

Acidic solutions

11

Acidic salts are most soluble in what kind of solution?

Basic solutions

12

How does a water softener work?

ion exchange column

Hard water (rich in Ca2+(aq)) travels down the column where the anion in the ion exchange resin binds calcium cations to form an insoluble salt while releasing sodium cations (Na+(aq)) into solution.

Aqueous sodium cation is referred to as soft water. As calcium precipitates through the ion exchange column, it is filtered from the water, preventing it from
forming precipitates in the plumbing lines of appliances (such as a washer or water heater).

The column is filled with an ion exchange resin. The cation to be precipitated must have a lower molar solubility with the anion of the resin than the salt in the resin.

13

Why would someone use molality instead of molarity?

Unlike molarity, a solution's molality is independent of temperature and pressure.

14

Does more sugar dissolve in hot or cold water?

Hot, because solids dissolve better in liquids with increasing temperatures

15

Why do scuba divers that ascend tot he surface too quickly risk having air bubbles in their body?

Gas tends to dissolve in liquid in high pressure, when you ascend to the surface, the pressure drops and gases reform.

16

Why does boiling water before making ice cubes out of it result in clear ice cubes that have no trapped air bubbles.

The solubility of gases in liquids decreases with increasing temperature and so the gases are separated better from the liquid before freezing.

17

How do you find the concentration of particles?

iM = van't Hoff factor * Molarity
or
im = van't Hoff factor * moles

18

What does colligative properties depend on?

Just the number of solute particles (van't Hoff factor), not the identity of the particle.

ex. one mole of surcrose (i = 1) will have the same number of particles in solution as 0.5 moles of NaCl (i = 2)

19

What is a volatile liquid?

Liquids easily vaporized, so they have high vapor pressure

20

What is vapor pressure?

Pressure exerted by gaseous phase of liquid that evaporated from exposed surface of liquid

21

What contributes to higher vapor pressure?

weaker intermolecular forces makes it easier to evaporate

22

What does colligative properties do to vapor pressure?

vapor-pressure depression
solutes attach onto solvent molecules and this make it harder for it to enter the gas phase because more energy is needed to break the solute's interaction with solvent.

23

If you add salt in a pot to cook spaghetti, will the temperature the water boils increase or decrease

Increase
if you add salt to cook sphagetti, it boils at a higher temperature than unsalted water because of colligative properties