ChE Calculations

• What is chemical engineering?

  Chemical engineering is a study of design and operation of chemical plants.
• what is dimension?

  a basic concept of measurement. It is a property that can be measured.
• Unit- means of expressing the dimension.
• Why is attaching a unit important?

  • Diminish possibility of errors in calculations
  • Reduce intermediate calculations and time in problem solving
  • Have a logical approach to the problem rather than remembering a formula and substituting numbers into it
  • Have easy interpretation of the physical meaning of the numbers you use
• system of units: a collection of units in which certain units are chosen as fundamental and all others are derived from them
• base units: the smallest unit of a physical quantity that can be measured and is independent of the units of measurement

  length, mass, time, temperature, electric current, luminous intensity, amount of substance
• multiple units: multiples or fractions of base units
• derived units

  1. multiplying or dividing base or multiple units (compound unit) 2. as defined equivalents of compound units
• dimensional homogeneity: equations must be dimensionally consistent

  each term in an equation must have the same net dimensions and units as every other term to which it is added, subtracted or equated
• scientific notation: a number is expressed as the product of another (usually between 0.1 and 10) and a power of 10. This is termed as Scientific Notation
• Mole: a certain amount of material corresponding to a specified number of molecules, atoms, electrons, or any other specified types of particles.
• Molecular Weight: weight of a given molecule
• Specific volume: inverse of density
• Density: substance's mass over volume
• Specific Gravity: ratio of the density of a substance to that of a reference substance (Water at 4degC for liquids and usually air for gases)
• Process: any operation or series of operations by which a particular objective is accomplished.
• Flow rate: For continuous processes, the flow rate of a process stream is the rate at which material is transported through a pipe
• Mass Flowrate: "mass (m) transported through a line per unit time (t)
• Molar Flow rate : number of moles (n) of a substance transported through a line per unit time (t)
• Volumentric Flow rate: volume (V) transported through a line per unit time (t)
• Mass fraction: "mass (weight) of a particular compound in a mixture or solution divided by the total mass (weight) of all the compounds in the mixture or solution
• Mole Fraction: number of moles of a particular compound in a mixture or solution divided by the total number of moles in the mixture or solution.