3. Salinity of Seawater

Question 1

Define Salinity

Answer 1

Salinity is defined as the ratio of electrical conductivity of the sample:

at 15oC and 1 atmosphere of pressure :

pottasium chloride (KCl) solution containing 32.4356g of KCl in 1kg of solution

Question 2

Define Concentration

Answer 2

Concentration is the measure of how much of a given substance there is mixed with another substance.

Question 3

What is the amount of a substance in chemistry measured in?

Answer 3

Moles

Question 4

What is the formula for finding number of moles?

Answer 4

Where

• n = number of moles
• m= mass in grams
• Mr= molar mass (Ar from periodic table)

Question 5

How can we find number of moles when given concentration and volume?

Answer 5

where:

• n= number of moles
• C= concentration
• V= volume in L

Question 6

What is molarity and what is its symbol?

Answer 6

Molarity is unit for concentration.

M (Capital) or mol/L

m (small= mass or moles)

Question 7

How do we find the concentration (molarity)?

Answer 7

Where:

• C= concentration
• n= number of moles
• V= volume in L

Question 8

1kg is equivalent to what in volume?

Answer 8

1kg= 1L

Question 9

Define freezing point depression

Answer 9

Freezing point depression is the temperature difference between the freezing point of a solution and the freezing point of its pure solvent.

It has a constant of -1.86^oC

Question 10

What is the formula for finding the freezing point?

Answer 10

Where:

• Tf= total freezing point
• Kf= freezing point depression constant
• meff= effective molality

Question 11

What is the difference between molarity and molality?

Answer 11

Molarity and molality are both measures of concentration of solutions.

Molarity is the ratio of moles to volume of the solution.

mol/L

Molality is the ratio of moles to the mass of the solution.

mol/ kg

Question 12

What is the formula for finding effective molality?

Answer 12

Question 13

How do you find molality?

Answer 13