Solutions

Question 1

Describe the process of solvation

Answer 1

Solvation is the breaking of intermolecular forces between solute particles and between solvant particles, with formation of intermolecular forces between solute and solvent particles. In an aqueous solution, water is the solvent.

Question 2

Describe the difference between solubility and saturation

Answer 2

Solubility is the amount of solute contained in a solvent. Saturation refers to the maximum solubility of a compound at a given temperature; you cannot dissolve any more of the solute just by adding more at this temperature

Question 3

What is one way in which solubility of a compound can be increased

Answer 3

Solubility of solids can be increased by increasing temperature.
Solubility of gases can be increased by decreasing temperature or increasing the partial pressure of the gas above the solvent (henry’s law)

Question 4

Name two ions that form salts that are always soluble

Answer 4

Group 1 metals, ammonium, NO3- (nitrate), acetate salts are always soluble

Question 5

Percent composition

Answer 5

(mass of Solute/Mass of solution) x 100

-For aqueous solution and solid-in-solid solution

Question 6

Mole Fraction

Answer 6

Xa= (moles of A/ Tot moles of all species)

-Used for calculating vapor pressure depression and partial pressure of gases in a system

Question 7

Molarity(M)

Answer 7

(moles of solute/Liters of solution)

- concentration and used in rate laws, law of mass action, osmotic pressure, pH and pOH and nernst equation

Question 8

Molality (m)

Answer 8

(moles of solute/kg of solvent)

-Used for boiling point elevation and freezing point depression

Question 9

Normality

Answer 9

Number of equivalents per liter

- molarity of a species of interest and is used for acid-base and oxidation reduction reactions

Question 10

Ion Product (IP)

Answer 10

Similar to Q

- to determine where the system is with respect to equilibrium position

Question 11

IP

Answer 11

Unsaturated so dissolution

Question 12

IP=Ksp

Answer 12

Saturated; equilibrium

Question 13

IP>Ksp

Answer 13

supersaturated; precipitate

Question 14

Kf

Answer 14

Formation or stability constant (Kf): it is the equilibrium contant for complex formation. Its value is usually greater than Ksp because complex ion in solution greatly increases solubility

Question 15

Colligative properties

Answer 15

Physical properties of solutions that depend on the concentration of dissolved particles but not their chemical identity
- Vapor pressure, boiling point elevation, freezing point depression, osmotic pressure

Question 16

Raoult’s law

Answer 16

Pa=XaPa
-The presence of other solutes decrease the evaporation rate of a solvent without affecting its condensation rate, thus decreasing its vapor pressure

Question 17

How are molality and molarity related for water and for other solvents

Answer 17

Water: m and M are nearly equal at room temperature because 1L solution is 1kg solvent for dilute solutions
Other solvents: m and M differ significantly because their densities are not 1g/ml like water