The document Work, Heat And Energy - Thermodynamic Chemistry Notes | EduRev is a part of the Chemistry Course Physical Chemistry.

All you need of Chemistry at this link: Chemistry

**WORK, HEAT AND ENERGY****When process is isothermal:** Ideal gas equation is: PV = nRT

When process is isothermal then

PV = constant

i.e., P_{1}V_{1} = P_{2}V_{2}

**When possible is adiabatic:**

According to first law dq = dU â€“ Ï‰

dq = dU + Pdv (Ï‰ = â€“Pdv)

â‡’ dq = CV dT + pdv (dU = CVdT)

When process is adiabatic then dq = 0

i.e. 0 = CVdT + PdV

âˆµ

â‡’

â‡’

â‡’

â‡’

â‡’ putting the value o f CV

â‡’

â‡’

Integrate this equation we get

Constant (C) = ln T + ln V^{r â€“ 1} = ln TV^{r â€“ 1 }

i.e. TV ^{r - 1} = constant

like this we can solve

PV^{r} = constant,

i.e. for adiabat ic process

PV^{r} = constant

V^{r â€“ 1}T = constant

T^{r}P^{1 â€“ r} = constant

where Î³ is atomicity and is equal to

Isothermal process: Is of two type (1) reversible and irreversible

**ISOTHERMAL WORK, HEAT AND ENERGY**

**(A) When process is reversible:** We know that in reversible process infinit e small change takes place i.e. integration will be possible in reversible process.**Work in reversible process: **We know that

W = - P_{ext} dV

where P is pressure & dV is change in vo lume it is posit ive.

Let expansion of gas from volume V_{1} and V_{2} isothermal expansion.

W = â€“ P dV

where know in isothermal process

PV = constant

P_{1}V_{1 }= P_{2}V_{2}

When V_{1} < V_{2} or P_{1} > P_{2} then expansion takes place and work is negative. When V_{1} > V_{2} or P_{1} < P_{2} then compression takes place & work is posit ive.

**Energy in isothermal reversible process:**

dH = nC_{P}dT

when process is isothermal then dT = 0 then

dH = 0

dV = nC_{V}dT

when process is isothermal then dT = 0 then

from first law, dq = dU â€“ Ï‰ and

dU = 0 dq = â€“Ï‰

**Isothermal irreversible work, heat & energy:** When process is irreversible then process is very fast and integration will not possible.

**Work in irreversible process: **

W = - P_{ext} dV

Let expansion of gas from volume V_{1} and V_{2} from pressure P_{1 }to P_{2 }then P_{2} is external pressure:

W = - P_{ext }dV = â€“P_{2} (V_{2} â€“ V_{1})

W = â€“P_{2} (V_{1} â€“ V_{1})

P_{1}V_{1} = nRT

P_{2}V_{2} = nRT

and

If expansion of gas from volume V_{1} to V_{2} & P_{1} to P_{2 }against pressure P_{3} then

Offer running on EduRev: __Apply code STAYHOME200__ to get INR 200 off on our premium plan EduRev Infinity!

77 videos|83 docs|32 tests

### First Law of Thermodynamics

- Video | 11:27 min
### Introduction & Basic Concepts of Thermodynamics

- Video | 19:41 min
### Test: Thermodynamics And Thermochemistry- 3

- Test | 30 ques | 90 min
### Recall the Maxwell equations - Thermodynamics

- Video | 04:27 min
### Thermodynamic Equation Of State - Thermodynamics

- Video | 16:47 min
### Thermodynamic Equation Of State - Thermodynamic

- Doc | 2 pages

- Introduction & Basic Concepts of Thermodynamics
- Doc | 3 pages
- Thermodynamic Magic Square - Thermodynamic
- Doc | 2 pages