SNS - General Chemistry - Solutions

Question 1

Solutions

Solute

Answer 1

Substance that is dissolved in a solution

Question 2

Solutions Solvent

Answer 2

Dissolving medium of a solution; usually the component present in greater amounts

Question 3

Solutions Electrolyte

Answer 3

Solute that produces ions in solution (conducts electric current)

Question 4

Solutions Non-Electrolyte

Answer 4

Substance that doesn’t ionize in water, thereby resulting in a nonconduction solution

Question 5

Solutions Saturated Solution

Answer 5

Solution that has the minimum amount of solute that can be dissolved in the solvent at the particular temperature

Question 6

Solutions Unsaturated Solution

Answer 6

Solution that has more capacity for solute to be dissolved

Question 7

Solutions Supersaturated Solution

Answer 7

Solution containing more solute that a saturated solution

Question 8

Solvation

Answer 8

Clustering of solvent molecules around a solute

Question 9

Solutions Hydration

Answer 9

Water is the solvent that clusters around solute

Question 10

Solutions Miscible

Answer 10

Capable of mixing in all proportions

Question 11

Solutions Concentration Calculations Molarity (M)

Answer 11

The number of moles of solute per litre of solution

Question 12

Solutions Concentration Calculations Molality (m)

Answer 12

The number of moles of solute per kg of solvent

Question 13

Solutions Concentration Calculations Normality (N)

Answer 13

The number of equivalents of solute per litre of solution - basically the number of H+ or OH- ions that dissociate in solution For example, the normality of 2.5M of H2SO4 = 2 x 2.5 = 5N

Question 14

Solutions Concentration Calculations Mole Fraction

Answer 14

The ratio of the number of moles of a particular component to the total number of moles ina solution. For example, the mole fraction of water in a solution containing 3 moles of water and 2 moles of methanol = 3/5 = 0.6

Question 15

Solutions Concentration Calculations Weight Fraction

Answer 15

= grams of component/total grams of solution

Question 16

Solutions Concentration Calculations Weight/Volume Percent

Answer 16

= (weight of solute (g)/volume of solution (ml) ) x 100%

Question 17

Solutions Concentration Calculations Density

Answer 17

Equal to mass/volume This value can be used ot calculate the weight percent. For exampe, Solution X with a molarity of 1.433M and a density of 1.012 g/ml. If each ml has a mass of 1.012g, 1000ml has a mass of 1012g

Question 18

Solutions Concentration Calculations Dilution

Answer 18

If a solution is diluted or concentration, the number of moles doesn’t change but the volume of solution and concentration do change M1 x V1 = M2 x V2

Question 19

Precipitation Ksp

Answer 19

Solubility product constant AxBy (s) xA^y+ (aq) + yB^x- (aq) Ksp = [A^y+] x [B^x+]

Question 20

Precipitation Ion product

Answer 20

The product of the concentrations of the dissolved ions, each raised to its stoichiometric coefficient

Question 21

Precipitation Ksp when the molar solubility in water of Pb(IO3)2 is 4x10⁻⁵ moles per litre.

Answer 21

Pb(IO3)2 (s) Pb²+ (aq) + 2IO₃- (aq) Ksp = [Pb²+] x [IO₃-]² = (4x10−⁵) (8x10−⁵)² = 2.6x10-¹³

Question 22

Precipitation Ion product Ion product < Ksp

Answer 22

Unsaturated solution. No precipitate will form

Question 23

Precipitation Ion product Ion product = Ksp

Answer 23

Saturated solution. No precipitate will form

Question 24

Precipitation Ion product Ion product > Ksp

Answer 24

Saturated solution. Precipitation occurs

Question 25

Solubility

Carbonates

Answer 25

Insoluble

Question 26

Solubility

Phosphates

Answer 26

Insoluble

Question 27

Solubility

Sulphides

Answer 27

Insoluble

Question 28

Solubility

Sulphites

Answer 28

Insoluble

Question 29

Solubility

Exceptions to the sulphide, sulphate, carbonates and phosphate solubility

Answer 29

Alkali metals

Ammonium

Question 30

Solubility

Hydroxides

Answer 30

Insoluble, with the exception of alkali metals and Ca2+, Sr2+ and Ba2+

Question 31

Solubility

Metal Oxides

Answer 31

Insoluble with the exception of alkali metals and CaO, SrO and BaO

Question 32

Solubility

Salts of sulphate ion (SO4^2-)

Answer 32

Soluble with the exception of Ca2+, Sr2+, Ba2+ and Pb2+

Question 33

Solubility

Chlorides, bromides and iodides

Answer 33

Soluble, except Ag+, Pb2+ and Hg₂2+

Question 34

Solubility

Salts of the ammonium (NH4+) ion

Answer 34

Soluble

Question 35

Solubility

Alkali metal salts

Answer 35

Soluble

Question 36

Ions

Suffixes

-ous and -ric

Answer 36

For elements which can from more than one positive ion, the endings -rous and -ric represent the ions with lesser and greater charge respectively:

Fe2+ : ferrous, Fe3+ : ferric

Cu2+ : cuprous, Cu3+ : cupric

Question 37

What is the percent composition by mass of a salt water solution if 100g of the solution contains 20g NaCl?

Answer 37

= 20/100 x 100%

=20%

Question 38

If 92g glycerol is mixed with 90g water what will be the mole fractions of the two components

MW H2O = 18, MW C3H8O3 = 92

Answer 38

Moles H2O = 90/18 = 5

Moles C3H8O3 = 92/92 = 1

x_water = 5/6 = 0.833

x_glycerol = 1/6 = 0.167

Question 39

If enough water is added to 11g CaCl2 to make 100ml solution, what is the molarity of the solution?

Answer 39

1M is 1mol per litre

Moles CaCl2 = 11/(110) = 0.1

= 0.1 x (1000/100) = 1M

Question 40

If 10g NaOH is dissolved in 500g water, what is the molality?

Answer 40

Moles NaOH = 10/40 = 0.25

Molality = 0.25 x (1000/500) = 0.5m

Question 41

How many ml of a 5.5M NaOH solution must be used to prepare a 300ml of 1.2M NaOH solution?

Answer 41

0.3 x 1.2 = x5.5

x = 65ml

Question 42

Solution Equilibria

Answer 42

The process of solvation, like other reversible chemical and physical changes, tends towards an equilibrium. An ionic solid introduced into a polar solvent dissociates into its component ions:

A_mB_n (s) ⇔ mAn⁺ (aq) + nBm^- (aq)

Question 43

Ion Product

Answer 43

A slightly soluble ionic solid exists in equilibrium with its saturated solution:

A_mB_n (s) ⇔ mAn⁺ (aq) + nBm^- (aq)

The ion product is:

=[An⁺]m[Bm^-]n

Question 44

Solubility Product Constant

Answer 44

A slightly soluble ionic solid exists in equilibrium with its saturated solution:

AmBn (s) ⇔ mAn+ (aq) + nBm- (aq)

The solubilty product constant, Ksp is:

=[An+]m[Bm-]n in a saturated solution.

While ion product is defined with respect to initial concentrations and doesn’t necessarily represent either an equilibrium or a saturated solution, Ksp does. At any point other than equilibrium, the ion product is often referred to as Qsp

Each salt has its own characterisitic Ksp at a given temperature. If at a given temperature a salt’s IP=Ksp, the solution is saturated and the rate at which the solid dissolves is equal to the rate at which it precipitates out of solution

Question 45

The solubility of Fe(OH)3 in an aqueous solution was determined to be 4.5 x 10^-10 mol/L. What is the value of the Ksp for Fe(OH)3?

Answer 45

AmBn ⇔ mAⁿ⁺ + nB^m- Fe(OH)3 ⇔ Fe³⁺ + 3OH^- m=1, n=3

Ksp = [Aⁿ⁺]^m [B^m-]ⁿ Ksp = [Fe3+] [OH-]³

[Fe3+] = 4.5 x 10^-10 = 3[OH-]

Ksp = (4.5 x 10^-10) (3 x 4.5 x 10^-10)³ = 1.1 x 10^-36

Question 46

What are the concentrations of each of the ions in a saturated solution of PbBr2 given that the Ksp of PbBr2 is 2.1 x 10^-6?

If 5g PbBr2 is dissolved in water to make 1L solution at 25^oC would the solution be saturated, unsaturated or supersaturated?

Answer 46

PbBr2 ⇔ Pb²⁺ + 2Br^-

Ksp = [Pb²⁺] [Br^-]² = [x] [2x]² = 4x³ = 2.1 x 10^-6

x = 8.07 x 10^-3M

Moles PbBr2 = 5/136 = 1.36 x 10^-2 mol dissolved in 1L solution, solution is supersaturated

Question 47

The Ksp of AgI solution is 1 x 10^-16 mol/L. If a 1 x 10^-5 M solution of AgNO3 is saturated with AgI what will be the final concentration of iodide ions?

Answer 47

Ksp = 1 x 10^-16 = [Ag+] [I-] = (1 x 10^-5) [I-]

[I-] = 1 x 10^-11