Unit 4, Solutions and Solubility

Question 1

Dilution

Answer 1

the process of adding water to a concentrated or stock solution to achieve the molarity desired for a particular solution
*diluting with water does not alter # of moles, but does decrease concentration
*M1V1 = M2V2

Question 2

pH scale

Answer 2

a scale used to describe the acidity or basicity of a solution, based on the concentration of hydrogen ions in solution
*0-14, 0 = acidic, 14 = baisc, power of 10 btwn each number
*measures the hydrogen (hydronium) ion concentration

Question 3

Precision Rule

Answer 3

addition and subtraction
use least number of decimal places

Question 4

Certainty rule

Answer 4

multiplication and division
least number of significant digits

Question 5

Types of solutions

Answer 5

1. liquid solutions: S/L/G, D in L
2. Gaseous solutoins: G, D in G
3. Solid solutions: S, D in S- to create homogenous mixture

Question 6

Solution

Answer 6

homogenous mixture

Question 7

solute

Answer 7

substance being dissolved

Question 8

solvent

Answer 8

present in greater amount

Question 9

Unsaturated solution

Answer 9

More of the solute can dissolve in the given volume of solvent.

Question 10

Saturated solution

Answer 10

The solvent has dissolved the maximum amount
of solute possible at that current temperature.

Question 11

Supersaturated solution

Answer 11

An artificially created solution, that
contains more solute than would normally dissolve at a given
temperature. Involves heating, followed by gentle cooling.
A supersaturated solution is unstable/fragile.

Question 12

Concentration

Answer 12

• Molarity (M)
• represented with [ ]
• the amount of solute dissolved in a given amount of solution
• mol/L or M
• concentration = (quantity of solute) / (quantity of solution) = (moles of solute) / (litres of solution)
• M = n / V(solution)
• V(solution) = V(solute) + V(solvent)

Question 13

Concentrated solution

Answer 13

the greater the amount of the solute, the more concentrated the solution

Question 14

Dilute solution

Answer 14

very small amount of solute compound to amount of solvent, generally safer

Question 15

Solubility curve

Answer 15

• a graph representing the solubility of a substance at various temperatures
• on line = saturated solution
• above line = supersaturated solution
• below line = unsaturated solution

Question 16

Solubility

Answer 16

• the relative ability of a solute to dissolve into a solvent
• many factors affect it: temperature (main one), pressure
• temperature: solids in liquids (temp up = solubility up), gases in liquids (temp up = solubility down, since the gas will evaporate and leave solution), liquids in liquids (no really change)
• pressure: only really affects gases in liquids (higher pressure = increased solubility of gases in liquids- Henry’s Law)

Question 17

Hydronium Ion

Answer 17

H3O+(aq)
pH of a solution is related to the quantity of hydronium ions in a given amount of solution

Question 18

Bronsted-Lowry acids and bases

Answer 18

• an acid is a proton (H+) donor, and a base is a proton acceptor
• nitrogen and OH- are basic
• Steps:
  1. Label acid and base
  2. draw an arrow showing the acid donating an H+ ion to base
  3. Write new conjugate base (acid minus H+) and conjugate acid (base with extra H+), label them and draw the line connecting it to the oposite on other side
  4. remember to write charges on new things (except water) (if lost H+, charge is now neg, and vise versa)

Question 19

Properties of acids

Answer 19

• sour taste
• turns blue litmus paper red
• reacts iwth some metals to produce H2
• dissolves carbonate salts, releasing CO2

Question 20

Properties of bases

Answer 20

• bitter taste
• turns red litmus paper blue
• slippery to the touch

Question 21

Reactions of acids

Answer 21

1. Reactions that react with metals above hydrogen on the reactivity series produce H2(g)
2. Hydrochloric acid also reacts with carbonate compounds to produce CO2 (g), a salt, and H2O (l)
3. Acids and bases neutralize each other (acid + base –> salt + H2O (l)

Question 22

Electrolytes

Answer 22

acids and bases are electrolytes because they produce ions in solution

Question 23

Strong/weak acids and bases

Answer 23

strong acid/base: dissociates (ionizing) completely (99%), use –> to show dissociation of ions
weak acid/base: only dissociates slightly (2-6%), double arrow is used <—>

Question 24

Titration

Answer 24

a lab technique that puts to use neutralization of acids and bases.
It is specifically used to determine the
concentration of an unknown solution.

Question 25

2 ways to change pH of solution

Answer 25

1. Dilution of solution- when diluting, H+ concentration changes by adding volume of solvent 2. Acid base neutralization reaction (most effective) H+ combine with OH- to form H2o and salt

Question 26

# Titration Reaching endpoint

Answer 26

- solution in burette is added to unknown solution drop by drop until colour change occurs - equivalent point: [acid] = [base]

Question 27

Arrhenious theory

Answer 27

- acids and bases must dissociate to form H+ (acid) and OH- (base) in solution - ex. HCl or NaOH - defines acids and bases in H2O

Question 28

Ionic character

Answer 28

- Ionic character in a chemical bond refers to the degree to which electrons are transferred between two atoms rather than shared, resulting in a partial ionic or ionic bond. - basically electronegativity, increases as you go up and to the right