Lecture 2: Mass and Energy Balance

Question 1

what principle is mass balance based on?

what law is this?

Answer 1

that matter cannot be created or destroyed

this is the law of mass conservation

Question 2

what general equations are assumed in mass balance?

Answer 2

mass in = mass out
or
mass in - mass out = mass accumulated or mass lost

Question 3

what is the pearson square rule

Answer 3

a simplified solution for mixing products based on an equilibrated mass balance

it is applied for mixing two syrups with different sugar concentrations to obtain a third product of specified concentration

Question 4

what is squash?

Answer 4

• a product popular in many tropical countries
• a bottled beverage with 15% or more fruit pulp
• sugar syrup can be added to increase the soluble solids content to ~40%
• acid and essence can be added to be diluted to 1:3 before consumption
• beverage is hot filled to a bottle and preserved with a preservation (sodium benzoate or potassium meta bi-sulfate)

Question 5

energy balance is used to account for what?

Answer 5

various forms of energy in a system

Question 6

how is energy balance different than mass balance?

Answer 6

mass balance accounts for thermal properties

Question 7

what principle is energy balance based on?

Answer 7

principle of conservation expressed by the first law of thermodynamics

Question 8

what is the equation of sensible heat?

Answer 8

Q = m* Cp * delta t

Question 9

what is the equation of latent heat?

Answer 9

Q = m*L

or Q = m * lambda