Chemical Reaction Engineering Flashcards

1
Q

What is a chemical reaction?

A

A process where one or more substances are converted to one or more different substances.
There is a change in CHEMICAL IDENTITY

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define Conversion

A

Conversion is used to measure the progress of a reaction
n. reacted / n. fed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define Yield

A

Yield shows how much of a reactant was transformed into a desired product

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define Selectivity

A

Selectivity shows the fraction of a desired product in all products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define Chemical Equilibrium

A

Chemical Equilibrium is the state of a system where all reactants and products are present with NO TENDENCY FOR FURTHER CHANGE in conc. over time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Gibbs free energy equation used for

A

To calculate composition of reaction mixture at eq. under chosen react. cond.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define Steady State

A

Steady state is where there are NO CHANGES IN TIME in composition of reaction mixture and conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Define Rate of reaction

A

Rate of reaction gives quantitative info about the process and changes in reaction conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define Space/Residence time

A

Space/Residence time is the time needed to PROCESS ONE REACTOR VOLUME OF FLUID @ set inlet conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the Space/Residence time equation

A

Volume of reactor / volumetric flow rate of fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define Space velocity

A

Space velocity is the ratio of the volumetric flow rate and reactor volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the Space velocity equation

A

SV = 1/residence time = volumetric flow rate/ volume of reactor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the rate of reaction equation?

A

-rA = moles of A consumed / (vol)(time)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How to find instantaneous rate of reaction

A

It is an infinitely small interval of time, expressed as limit or DERATIVE EXPRESSION

 rA = -(ΔCA/Δt)  --> rA = -lim(ΔCA/Δt) --> rA = - dCA / dt
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Define Rate Law

A

Rate Law describes relationship of reaction rate & reactant conc. in an eq.

-rA = k (CA)^m (CB)^n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Factors affection RoR

A
  • Temperature
  • Reaction Order
  • Conc.
  • (Pressure)
  • (Catalyst)
17
Q

What is the Arrhenius Equation

A

k= Ae^(-Ea / RT)

lnk = (-Ea/R) (1/T) + lnA
y = m x c

18
Q

What do Conc/Time graphs look like

19
Q

What do Rate/Conc graphs look liek

20
Q

How to determine k from 1st/2nd order reactions

A

1st Order: ln(Co/C) / time graph, m = k
2nd Order: 1/C / time graph, m = k

21
Q

What is a Batch Reactor and conditions

A

1-10,000L vessels
With controlled temp/pres/vol @ UNSTEADY state

22
Q

Batch Reactor Advantages

A
  • HIGH CONVERSIONS
  • Batch reactor jacket changes heating/cooling
  • Versatile, (consecutive production of products)
  • Produces small amount of products in TESTING PHASE
23
Q

Batch Reactor Disadvantages

A
  • HIGH COST of LABOUR
  • Hard MAINTAINANCE
  • Lots of time CLEANING
24
Q

Batch Reactor Application

A
  • LIQUID PHASE reaction @ high temp w/ biological materials
  • chem/pharma/food industry:
    • fermentation
    • sewage treatment
    • photobioreactors
25
What is a Semi-Batch Reactor and conditions
- Reactant added CONTINUOUSLY to another reactant - optimal for GAS & LIQ. reactions, no bubble formation (unlike batch)
26
What is a Tubular / Plug Flow Reactor and conditions
- reactants flow continuously @ STEADY STATE
27
What affects diameter size in PFR
- construction/pumping cost - desired residence time - heat transfer needs LOW DIAMETER = HIGH RoR
28
What is a Continuous Flow Reactor and conditions
- CONTINUOUS feed of reactants and withdrawal of products - for HGIH QUANTITIES of products - must run for months
29
Define Parabolic Flow Rate
- LOWER flowrate (velocity) than turbulent - LAMINAR flow - Re > 2100 - no eddies & no mixing
30
Define Flat Flow Rate
- HIGHER flowrate (velocity) than laminar - TURBLUENT / plug flow - Re > 2100 - RANDOM eddies & mixing
31
Tubular Reactor Applications
- Hydrogenation - Hydrocracking - Polymerization - Reforming - Catalytic Converters
32
Tubular Reactor Advantages
- Either small / large scale - HIGH CONVERSION - NO RADIAL VARIATION in CONC - GOOD HEAT TRANSFER - LOW OPERATING COST
33
Tubular Reactor Disadvantages
- undesired THERMAL GRADIENTS - CHANNELLING may occur - Shutdown & cleaning could be EXPENSIVE
34
What is a Continuous Stirred Tank Reactor and conditions
- Has constant volume and stirring - OPEN system & STEADY STATE - in series
35
CSTR Application
- Homogenous liq-phase flow reactions -pharma / biological processes (fermentation)
36
CSTR Advantages
- easy to maintain temp - LOW UPFRONT cost - HIGH HEAT CAPACITY - accessible interior
37
CSTR Disadvantages
- LOW CONVERSION - (small reactor)