Topic 5 + 6

Question 1

What are COLLIGATIVE PROPERTIES OF SOLUTIONS?

Answer 1

The physical properties of a solution that depend only on the concentration of solute particles in a given quantity of solute, not on the chemical identity of the particles.

Question 2

What is vapor pressure?

Answer 2

the pressure exerted by a vapor above a liquid when the liquid and vapor are in equilibrium with each other.

Question 3

What is vapor pressure lowering?

Answer 3

the pressure exerted by a vapor above a liquid when the liquid and vapor are in equilibrium with each other.

Question 4

Does vapor pressure depend on temperature?

Answer 4

Yes

Question 5

What does non-volatile solute mean?

Answer 5

not easily vapourized solute

Question 6

Compare vapor-pressure of non-volatile solution to that of pure solvent

Answer 6

A solution that contains a non-volatile (not easily vapourized) solute always has a lower vapour-pressure than the pure solvent

Question 7

Describe equilibrium of vapor pressure of pure solvent

Answer 7

Vapor pressure is higher

Question 8

Describe equilibrium of vapor pressure of pure solvent

Answer 8

Vapor pressure is higher

→ Equilibrium is established between the liquid and vapour in a pure solvent

Question 9

Describe equilibrium of vapor pressure of solution containing non- volatile solute

Answer 9

In a solution, hydrated solute particles reduce the number of solvent particles able to leave the liquid.

→ Equilibrium is attained at a lower vapour pressure.

Question 10

Formula for Raoult’s law

Answer 10

vapour-pressure lowering is proportional to the mole fraction of the non-volatile solute

Question 11

This is the phase diagram of which substance?

Answer 11

Pure water

Question 12

What is boiling?

Answer 12

a form of evaporation where conversion from the liquid state → the vapor state occurs within the body of the liquid through bubble formation

Question 13

What is boiling point?

Answer 13

the temperature at which the vapor pressure of a liquid becomes equal to the external (atmospheric) pressure exerted on the liquid

Question 14

What is BOILING-POINT ELEVATIONt?

Answer 14

Addition of a nonvolatile solute to a solvent

→ makes the boiling point of the solution HIGHER than that of the solvent alone.

Question 15

Calculate

Boiling-point elevation of solutions

Answer 15

Question 16

What is FREEZING-POINT DEPRESSION?

Answer 16

Addition of a nonvolatile solute to a solvent

→ makes the freezing point of the solution LOWER than that of the solvent alone.

Question 17

Calculate

Freezing-point depression of solutions

Answer 17

Question 18

What is the van’t Hoff factor (i)?

Answer 18

The factor that denotes the total number of dissolved particles

Question 19

What is the relationship between colligative properties and osmolarity of solution?

Answer 19

Colligative properties are proportional to the osmolarity of the solution

Question 20

What is osmosis?

Answer 20

the passage of a solvent through a semipermeable membrane separating a dilute solution (or pure solvent) from a more concentrated solution.

Question 21

What is osmosis?

Answer 21

the passage of a solvent through a semipermeable membrane separating a dilute solution (or pure solvent) from a more concentrated solution.

Question 22

What is a semi-permeable membrane?

Answer 22

A membrane that allows certain types of molecules to pass through it but prohibits the passage of other types of molecules

Question 23

What is a semi-permeable membrane?

Answer 23

A membrane that allows certain types of molecules to pass through it but prohibits the passage of other types of molecules

Question 24

What is Osmotic pressure?

Answer 24

the pressure that must be applied to prevent the net flow of solvent through a semipermeable membrane from a solution of lower solute concentration to a solution of higher solute concentration

Question 25

What is osmolarity?

Answer 25

The product of a solution’s molarity and the number of particles produced per formula unit if the solute dissociates.

Osmolarity = molarity x i

i - the number of particles produced from the dissociation of one formula unit of produced per formula unit if the solute dissociate

=> The abbreviation for osmolarity is osmol.

Question 26

What is the osmolarity of 2M NaCl?

Answer 26

Osmolarity = molarity x i

2 particles per dissociation are produced when NaCl dissociates in solution.

NaCl → Na+ + Cl-

=> i is 2 → the osmolarity is twice the molarity.

Osmolarity = 2 M x 2 = 4 osmol

Question 27

What is the osmolarity of 2M CaCl2?

Answer 27

Osmolarity = molarity x i

For CaCl2, the value of i is 3, because three ions are produced from the dissociation of one CaCl2 formula unit.

CaCl2 → Ca2+ + 2Cl-

The osmolarity will therefore be triple the molarity:

Osmolarity = 2M x 3 = 6 osmol

Question 28

What is the osmolarity of 2 M glucose?

Answer 28

Glucose is a nondissociating solute.

→ Thus the value of i is 1, and the molarity and osmolarity will be the same—two molar and two osmolar.

Question 29

What is the osmolarity of 2 M in both NaCl and glucose?

Answer 29

With two solutes present, we must consider the collective effects of both solutes. For NaCl, i 􏰂 2; and for glucose, i 􏰂 1. The osmolarity is calculated as follow

Osmolarity = 2 M x 2 = 2 M x 1 = 6 osmol

Question 30

What is the formula for Osmotic pressure (π)?

Answer 30

• *1 mol/liter = 1 mol/0.001 m3 = 1000 mol/m3,**
• *so if concentration is given in mol/liter, you get the**

pressure in kilopascal!!!

Question 31

What is HYPOTONIC SOLUTION?

Answer 31

1. Solution with an osmotic pressure LOWER than that in cells.
2. Causes cells to hemolyze (burst).

Question 32

What is HYPOTONIC SOLUTION?

Answer 32

1. Solution with an osmotic pressure HIGHER than that in cells.
2. Causes cells to crenate (shrink).

Question 33

What is HYPOTONIC SOLUTION?

Answer 33

1. Solution with an osmotic pressure EQUAL to that in cells.
2. Has no effect on cell size.