Lecture 3 (Physical properties)

Question 1

What are the characteristics of Solutions?

Answer 1

• Transparent to light
• Does not separate on standing
• Non-filterable

Question 2

What are the characteristics of Colloids?

Answer 2

• Murky/opaque to light
• Does not separate on standing
• Non-filterable

Question 3

What are the characteristics of Heterogenous mixtures?

Answer 3

• Murky/opaque to light
• Separates on standing
• Filterable

Question 4

What is a Homogenous mixture?

Answer 4

A uniform mixture that has the same composition throughout

Question 5

What is a solution?

Answer 5

A homogenous mixture that contains particles the size of a typical ion or small molecule

Question 6

What is a colloid?

Answer 6

A homogenous mixture that contains particles that range in diameter from 2 to 500nm

Question 7

Why don’t oil and water mix?

Answer 7

Because they have different intermolecular forces

Question 8

What are Solid hydrates?

Answer 8

Ionic compounds that attract water strongly enough to hold onto water molecules even when crystalline

Question 9

What is the difference in effect of temperature on solubility in solids and gases?

Answer 9

SOLIDS: as temperature increases, solubility INCREASES

GASES: as temperature increases, solubility DECREASES

Question 10

Define Henry’s law

Answer 10

The solubility (or concentration) of a gas is directly proportional to the partial pressure of the gas if temperature is constant

[concentration (C) divided by pressure (P) is constant when T is constant]

Question 11

How do you calculate Molarity (M)?

Answer 11

Moles of solute / Volume of solution

Question 12

How do you calculate Moles of solute?

Answer 12

Molarity X Volume of solution

Question 13

How do you calculate Volume of solution?

Answer 13

Moles of solute / Molarity

Question 14

What is a way of expressing percent concentration of a solution?

Answer 14

Weight/volume percent concentration

W/V% concentration = Mass of solute (g) / Volume of solution (mL) X 100

Question 15

What is a way of expressing a volume of solute as a % of the volume of final solution?

Answer 15

Volume/volume percent concentration

V/V% concentration = Volume of solute (mL) / Volume of solution (mL) X 100

Question 16

What is the Dilution factor?

Answer 16

The ratio of the initial and final solution volumes (V1/V2)

Question 17

What is the difference between electrolytes and non-electrolytes?

Answer 17

ELECTROLYTES = dissolve in water and separate into ions forming solutions that are able to conduct electricity

NON-ELECTROLYTES = dissolve in water but as molecules not as ions -> solutions don’t conduct electricity

Question 18

What is the difference between a strong electrolyte, weak electrolyte and a non-electrolyte?

Answer 18

Strong electrolyte = completely dissociates into ions in an aqueous solution

Weak electrolyte = forms mostly molecules and a few ions in an aqueous solution

Non-electrolyte = dissolves as molecules in an aqueous solution

Question 19

What are the physical properties of solutions?

Answer 19

• VAPOR PRESSURE is lower for a solution than for a pure solvent
• BOILING POINT is higher for a solution than for a pure solvent
• FREEZING POINT is lower for a solution than for a pure solvent
• OSMOSIS occurs when a solution is separated from a pure solvent by a semipermeable membrane

Question 20

What is osmolarity?

Answer 20

The sum of the molarities of all dissolved particles in 1.0 liter of solution

Question 21

When are two liquids called Isotonic?

Answer 21

When they have the same osmolarity

Question 22

How is dialysis linked to osmosis?

Answer 22

In dialysis, the membrane allows the passage of solvent and small dissolved molecules but prevents passage of proteins and larger particles -> used to remove metabolic waste products from blood