Exam 1

Question 1

Molar conversations in solutions

Answer 1

atoms, ions, or molecules -> * NA -> moles

Mass (g) substance -> *mol/g -> moles
# atoms, ions, or molecules -> *NA -> moles
Concentration solution (M) -> * vol (L) -> moles
Volume solution (L) -> *mol/L -> moles

Question 2

Low boiling points =

Answer 2

Associated with low molecular weights; experience weaker intermolecular forces

Question 3

Hydrogen bonding

Answer 3

Hydrogen atom covalently bonded to N, O, F, any electronegative

Question 4

Volatile vs nonvolatile liquids

Answer 4

Volatile: Evaporates more easily, resulting in higher vapor pressure
Nonvolatile: Evaporates slowly and has low vapor pressure

Question 5

Exothermic

Answer 5

Heat given off in a system; surroundings get warmer (making beaker get warm); energy decreases; Delta H < 0; Product < Reaction
Condensation, deposition, freezing

Question 6

Endothermic

Answer 6

Heat absorbed by system; surroundings get colder (making beaker get cold); energy increases; Delta H > 0; Product < Reaction
Vaporization, sublimation, melting

Question 7

Solution

Answer 7

Homogenous mixture of 2+ substances; solutions can be liquid, solid, gas

Question 8

Solvent

Answer 8

Only one found in a solution; substance in highest quailty

Question 9

Solute

Answer 9

Can be more than one in a solution; substances other than solvent; dissolved in solvent

Question 10

Aqueous solution

Answer 10

Liquid solution where solvent is water

Question 11

Molarity (M)

Answer 11

moles of solute/liters of solution

Question 12

Mass percent

Answer 12

(Mass of solute/total mass of solution) *100

Question 13

Mole fraction of component A

Answer 13

XA = nA/(nA+nB)
nA: solute trying to find
nA + nB: sum of moles

Convert mass of solvent into moles using molar mass
Convert mass of solute into moles using molar mass
Used to find vapor pressure
Mole fractions: XA + XB = 1
Always less than 1; 0 < XA < 1; always decimal
No unit

Question 14

Molality (m)

Answer 14

moles of solute/kilograms of solvent
Used to find freezing point depression or boiling point elevation
Solvent: Determined by larger moles; base; used to dissolve

Question 15

Mass percent (w/w%)

Answer 15

(Mass solute/total mass solution) * 100; Parts per hundred

Question 16

Parts per million (ppm)

Answer 16

(Mass solute/total mass solution) * 10^6; Really small amount of solute in solution

Question 17

Parts per billion (ppb)

Answer 17

(Mass solute/total mass solution) * 10^9

Question 18

Like dissolves like

Answer 18

Polar dissolves polar; Nonpolar dissolves nonpolar

Question 19

Solvent-solvent interactions

Answer 19

IMF between 2 solvent molecules

Question 20

Solute-solute interactions

Answer 20

IMF between 2 solute molecules

Question 21

Solvent-solute interactions

Answer 21

IMF between 1 solute molecule and 1 solvent molecule