MOaD 8

Question 1

what is the general expression for hess law?

Answer 1

The general expression for calculating enthalpy changes is Hess’ Law for a reaction, which relies on the fact that H is a state function and so only the initial and final conditions matter.

Question 2

what is the Standard condition.

Answer 2

. These are T = 298.15 K and p = 1 atm = 101325 Pa.

Question 3

symbol that shows standard conditions

Answer 3

the plimsoll symbol (o).

Question 4

Hess’s law:

Answer 4

The standard enthalpy of an overall reaction is the sum of the standard enthalpies of the individual reactions into which a reaction may be divided.

Question 5

ΔH formula

Answer 5

= nCpΔT

Question 6

ΔHm formula

Answer 6

= Cp,mΔT

Question 7

ΔH varies with

Answer 7

temperature.

Question 8

kirckoff equation

Answer 8

𝐻_(𝑇_2 )= 𝐻_(𝑇_1 )+ ∫_(𝑇_1)^(𝑇_2)▒〖𝐶_𝑝 (𝑇).d𝑇〗

Question 9

The heat capacity at constant pressure for NH3 is given by:

Cp(NH3) = 33.8 + (2.9410-3)T + (21.4210-6)T 2

Calculate the change in enthalpy when the gas is raised from 300 K to 400 K.

Answer 9

slide 8

Question 10

enthalphy change kirchoff

Answer 10

〖Δ_r 𝐻〗(𝑇_2 )= 〖Δ_r 𝐻〗(𝑇_1 )+ ∫_(𝑇_1)^(𝑇_2)▒〖〖Δ𝐶〗_𝑝 (𝑇).d𝑇〗