Exam Q&A

Question 1

Write the type of thermodynamic process and properties

Answer 1

Adiabatic process: a process were no heat transfer into or out of the system process

Isochoric process: a process where no change in volume occurs in the system does not work

Isobaric process: a process in which no change in pressure occurs

Isothermal process: a process in which no change in temperature occurs

Question 2

State the definition of dynamic equilibrium

Answer 2

Rate of forward reaction = rate of backward reaction

Question 3

What are conjugate acids, base pairs with example

Answer 3

Pair of compounds that differ by a proton. Compounds which can mutually accept and donate hydrogen ions is called conjugate acid-base pair

Example: HClO4 —> H+ + ClO4-

Question 4

What is irreversible and reversible reaction with reaction

Answer 4

Reversible: Occurs in both directions, reactants can change to products also products can change into reactants

Irreversible: Occurs in one direction, when the reactants can change into products but products cannot change to reactants

Question 5

What is meant by electrolysis

Answer 5

The process of decomposition of an electrolyte by passage of electricity

Question 6

First and second law of thermodynamics

Answer 6

First law: “Energy can neither be created or be destroyed it can only be transferred from one form to another”

Second law: “ The entropy of any isolated system always increases”

Question 7

Molecule of ammonia react with borane. State the bonding and draw structure

Answer 7

Structure NH3 BH3

Dative covalent bond

Question 8

First 3 elements of period 3 shows a general increase in melting point, explain the trend in melting point across period 3 elements

Answer 8

Moving across period 3, the number of delocalized electrons per metal atom increases and radius of element decreases this increases melting point

Question 9

Electron configuration of potassium 2.8.8.1 and lithium is 2.1
Why is li more reactive than k?

Answer 9

K has more shells than Li. So the distance between the nucleus and outer most shell is greater in K which makes it easier for K to lose an electron

Question 10

What is enthalpy and entropy

Answer 10

Enthalpy: Enthalpy is the measurement of energy in the thermodynamics system
to calculate enthalpy (H) H=E+PV

Entropy: Entropy value depends on the physical state or condition of a system
Example the entropy of a solid, where the particles are not free to move, is less than the entropy of a gas where the particles will fill the container

Question 11

Role of salt bridge and diagram

Answer 11

Role of salt bridge: are u-shaped tubes made with agar-agar gel contains Kcl or KnO . Because there salts the ions have almost the same speed. If a salt bridge is not used, there will be accumulation of changes near two electrodes. The salt bridge provides a passage for the flow of charges in the internal circuit, -ve ions form copper electrode to zinc rod +ve ion zinc rod to copper rod. Hence flow of electricity is maintained

Question 12

What is electrochemical cell

Answer 12

Electrochemical cell: a device that converts electrical energy to chemical energy or vice versa through redox reaction

Question 13

Iodine and diamonds are crystals at room temperature. Why do diamonds have a higher melting point than iodine?

Answer 13

Because diamond has strong covalent bonds because of its 4 carbon atom forming a rigid tetrahedral structure. And these covalent bonds are extremely strong and requires a large amount of electricity to break, while iodine is held together by weak intermolecular forces leading to a lower melting point