Factors affecting solubility and rate of dissolving

Question 1

rate of dissolving

Answer 1

the speed at which the solute dissolves in a solvent

Question 2

ROD: SA

Answer 2

increasing the surface area of the solute by crushing it

Question 3

ROD: Heat

Answer 3

increasing the kinetic energy= higher collision frequency which means it dissolves faster

Question 4

ROD: Agitation

Answer 4

increases the rate of dissolving by allowing unsaturated portions of the solution to come in contact with the solute.

Question 5

Factors affecting ROD

Answer 5

SA, heat, agitation

Question 6

factors affecting solubility

Answer 6

temperature, pressure, molecule size, polarity, ionic size and charge

Question 7

solubility: temperature

Answer 7

For most solid solutes, solubility increases 
with heat. Heating increases the spaces between the solvent 
molecules to allow for more solutes to dissolve.

To increase the solubility of gases in liquids, the temperature 
must be dropped. The drop in temperature decreases the 
speed of motion of the gas molecules and therefore, prevents 
the gas molecules from escaping the liquid.

Question 8

solubility: pressure

Answer 8

Increasing pressure increases the solubility of gases 
in liquids, but since solids and liquids are not compressible, we cannot change the pressure in order to change solubility of solids and liquids. Pressure has a great effect on the solubility of a gas only.

Question 9

solubility: molecule size

Answer 9

Smaller molecules are more soluble than the 
larger ones.

Question 10

solubility: polarity

Answer 10

Polar solutes dissolve better in polar solvents. Non-
polar solutes dissolve better in non-polar solvents (“like dissolves like”).

Question 11

factors affecting solubility of ionic compounds

Answer 11

ion size: smaller the ion, less distance between nuclei, stronger the bond= harder to dissolve. attraction between the electron clouds of both ions is stronger
ion charge: stronger bond= harder to dissolve ex +2 and -2 is stronger than +1, -1

Question 12

molar concentration of ions

Answer 12

multiply by the subscripts

Question 13

what compounds are always soluble?

Answer 13

all compounds of alkali metals, ammonium and nitrates are water soluble

Question 14

liquid in liquid solubility and temperature

Answer 14

When two liquids at the same temperature mix to form a solution, there is usually little or no energy exchanged between the particles of the liquids. For tis reason, the solubility of one liquid in another liquid is not affected by temperature

Question 15

solubility of a gas in a liquid

Answer 15

• The solubility of a gas in a liquid depends on temperature and pressure
• There is a large change in the kinetic energy of gas molecules when they enter or leave a solution
• Molecules in the gas state have greater kinetic energy than the same molecules dissolved in a solvent
• Increasing the temperature for a solution that contains dissolved gas molecules provides energy for the gas molecules to escape
• solubility decreases
• the solubility of a gas in a liquid is directly proportional to the pressure of that particular gas above the liquid but is not affected by the pressure of any other gas