Tutorial 5 (Molarity, Molality, Milliequivalents, Millimoles and Milliosmoles)

Question 1

What are the units used for the volume and the mass?

Answer 1

L, Kg

Question 2

What is a mole?

Answer 2

A mole equals grams of substance/molecular weight of the substance
1 mole of a substance = molecular weight of a substance

Question 3

What are millimoles?

Answer 3

Millimoles (mmol) used to express electrolyte concentrations in millimoles per liter (mmol/L).
Moles is 1000 millimoles

Question 4

What is the weight, in milligrams, of 1 mmol of HPO4?
MWT:95.98

Answer 4

1millimoles=0.001moles
0.001=g/95.98
g=0.09598
mg=95.98mg

Question 5

Define molarity

Answer 5

Molarity (M) is defined as the number of moles of solute per liter of solution.

Question 6

Define molality

Answer 6

Molality (m) is defined as the number of moles of solute per kilogram of solvent.

Question 7

True or False
Molarity and Molality are always equal

Answer 7

False
Molarity and Molality are only equal in case of water

Question 8

What is the molarity of a solution that contains 210.0 g of Al2(SO4)3 in 2.75 liters of a solution?

Answer 8

n(Al2(SO4)3)= 0.613
M=n/L
M=0.613/2.75
M=0.2M

Question 9

What is the molality of a solution in which 49.0 g of H2SO4 is dissolved in 250 mL of water?
Mwt. of H2SO4 = 98.0

Answer 9

2m
Steps in tutorial 5 slides
Slide no. 15

Question 10

Define milliequivalents

Answer 10

concentration of electrolytes in solution is expressed in terms of milliequivalents
o For monovalent species, the numeric values of the milliequivalent and millimole are identical.
o For non-monovalent, the mmoles must be multiplied by their valence

Question 11

Osmolarity

Answer 11

number of milliosmoles per liter of solution.

Question 12

Osmole

Answer 12

A unit of measurement that defines the number of moles of solute that contribute to the osmotic pressure of a solution.

Question 13

Equation of the osmolarity

Answer 13

Osmolarity=Molarity×n