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Processes and Process

Variables

Chapter 2

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Mass and Volume

Densitymass/unit volume

g/cm3

Specific Volume volume/ unit mass

cm3 /g

Specific GravityDimensionless

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Specific Gravity

Ratio of the density of a substance to areference substance at a specific

condition

SG= ref 

The reference is often the density of

water at 4

0

C 1000 kg/m3 

62.43 lb/ft3 

1.000 g/cm3

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What Does this mean?

0

0

4

206.0SG

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American Petroleum Institute

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Example

Ex 2.5/ p. 54

Given: Volumetric flow rate = 10.5 L/min41.2% drug

sp. gr. =1.024

MW drug = 192

Required: a) conc. [kg/L]

b) flow rate [kgmol/min]

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 Flow Raterate at which material is transported in a pipe per unit

time

Mass flow rate

Mass/time

Volumetric flow rate

Volume/time

V 

m

V 

m

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Flow Rate Measurement

Flowmeter

Rotameter

Orifice Meter

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Example

Prob. 1/ p.57

Given: HC fuel

F = 40 gal/min sp. gr. = 0.91mass = 40,000 lb

Required: time to fill up

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Moles and Molecular Weight

Atomic Weight

Molecular Weight

gram-mole lb-mole

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Example

Ex 2.2/ p.46

Given:

2.00 lbmass of NaOHDetermine

a) lbmole of NaOH

b) gmole of NaOH 

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Mass and Mole Fraction

Mass fraction

Mole fraction

masstotal

Aof mass

 A x

molestotal

Aof moles

 A y

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Example

Ex. 2.6/p.57

Given:

solution: mass H2O = 7.5 kgmass NaOH = 6.5 kg

Required: mass fraction, mole fraction

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Multicomponent Solutions

Liquid/Solid mixtures  – assume %mass

Gas mixtures  – assume %n = %vol

Ex. Air ( 79% N2 and 21% O2)

MWave = 28.89 g/mol

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Example

Prob 3/p.61

Given

mixture %mn-C4H10 50

n-C5H12 30

n-C6H

1420

Required:

a) mass fraction c) % mole

b) mole fraction d) MWave

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Concentration

Mass concentrationMass/volume

Molar concentrationMoles/unit volume of the mixture

MolarityMolar concentration in gram moles per liter

of solutionppm and ppb

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Temperature

The degree of heat as an inherentquality of objects expressed as hotness

of coldness relative to something else.

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TYPES OF TEMPERATURESCALES

Relative Scale

Degree Fahrenheit (0F)

Degree Celsius (0C)

Absolute Scale

Degree Rankine (0

R)Kelvin (K)

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TEMPERATURE SCALES

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Temperature Conversion

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PRESSURE

The normal (perpendicular) force perunit area.

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PRESSURE

Absolute pressure = gauge pressure +barometer pressure

Gauge pressure (relative pressure)

is zero referenced against ambient air

pressureAbsolute pressure

is zero referenced against a perfect vacuum

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Atmospheric Pressure

Absolute pressure

Gauge pressure

Pabsolute = Pgauge + Patmospheric

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PRESSURE

Measured in psi, pascals, bars

Head

Height of a column of water or mercury 1 atm = a head of 33.9 ft of water

1 atm = a head of 760 mm of Hg

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Pressure Measurement

Bourdon Gauge

Manometer

Barometer

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In imperial units the Standard

 Atmospheric Pressure is 14.696 psi.

1 atm = 1.01325 bar = 101.3 kPa =

14.696 psi (lbf  /in2  )= 760 mmHg =10.33 mH 2 O = 760 torr = 29.92 inHg 

= 1013 mbar = 1.0332 kg f  /cm

2 

=33.90 ftH 2 O