Lecture Notes, Chapter 3
English & Metric Units and Dimensional Analysis


Kilo   k   1000
hecto   h   100
deca   da     10
unit              1
deci   d         0.1
centi   c        0.01
milli   m        0.001

mass in grams (g)     A nickel weighs about 5g.

distance in meters (m)     A nickel = 2 mm thick.

volume in liters (L)     1.057quarts = 1.000 liters
 

Mass is a measure of the quantity of matter.  Weight is a measure of the force of gravity on an object.
 

English Units

Length
12 inches (in.) = 1 foot (ft)
3 feet (ft) = 1 yard (yd)
5280 feet (ft) = 1 mile (mi)

Mass
16 ounces (oz) = 1 pound (lb)
2000 lb = 1 ton

Volume
2 pints (pt) = 1 quart (qt)
4 (qt) = 1 gallon (gal)

English/Metric   Conversions +
1 inch = 2.54 cm
1 pound = 453.6 g
1 quart = 0.946 L
1cm3 = 1 mL

Dimensional Analysis

Convert 27.2 ft. to meters (m).

27.2 ft x 12 in x2.54 cm   x 1 m = 8.29 m
1            1ft         1 in     100 cm
 

Convert 99 oz to kg.

99 oz x 1 lb x453.6 g  x 1 kg    = 2.8 kg
1         16 oz     1 lb      1000 g
 

Convert 1.0 ft3 to L

1.0 ft3 x12 in3 x 2.54 cm3x1 mL x 1 L     = 28 L
1            1 ft3        1 in1 cm3  1000 ml
 

Density = mass/volume

solids;     g/cm3
liquids;    g/mL
gases;      g/L

Sample densities

Au 19.3 g/cm3
H2O @ 4o C 1.00 g/mL
Air 1.29 g/L

Calculate the mass of 2500 mL of methane (density 0.714 g/L)

d = m ;     m = dv
      v
m = (2500mL) (0.714g/L) (1L/1000mL) = 1.785 g = 1.8 g
 

What is the mass in lbs. of 1.00 gal. H2O.
 

1.00 gal x 4 qt x 1 L      x 1000 mL x 1.00 g x1 lb      = 8.34 lb
                1 gal  1.057qt      1L         1 mL   453.6 g
 
 

Percentage = % = parts per 100

% = part x 100
      whole    1

Unless specified otherwise, we will use % by mass.

14-karat gold (Au) is 41.6 % copper (Cu). Calculate the mass of gold
in a 12.2 g 14-K gold ring. Let "R" stand for ring.
 

12.2 g R x 58.4 g Au = 7.12 g Au
    1            100. g R

% = part x 100
      whole    1

58.4 =  x       x  100
        12.2 g         1

x = (58.4) (12.2 g) = 7.12 g Au
             100

Temperature Scales
 
oF oC K
boiling point of H2O 212 100 373
freezing point of  H2O 32 0 273
absolute zero -460 -273 0

 

Temperature Conversions

K = oC + 273

oF = 1.8oC + 32

oC = (oF - 32 )
              1.8

Convert - 22oF to oC & K

oC = oF - 32
            1.8

oC = (-22 - 32) = - 30.oC
             1.8

K = 273 + oC

K = 273 + (-30) = 243 K

Energy = the capacity to perform work.
Common types of energy: mechanical, electrical, chemical, light, heat

Law of Conservation of Energy: In a non nuclear process energy can neither be created or destroyed.

Potential energy  = stored energy

Kinetic energy = energy due to the motion of matter

Units of Energy

J = Joule = kg m2
                  sec2

cal = calorie = heat needed to warm 1 g H2O from 14.5oC to 15.5oC

BTU = heat to warm 1 lb of H2O by 1oF

Specific heat (Sp. Ht.) = heat energy needed to warm 1 g of a substance by 1oC.

Examples
H2O(s) 2.1 J/goC
H2O() 4.184 J/goC
H2O() 1.00 cal/goC
Fe(s) 0.444 J/goC
O2(g) 0.92 J/goC

Heat is a measure of the quantity of energy while temperature is a measure of intensity.

Heat = (Sp.Ht.)(mass)( delta T)

 delta T = Tfinal - Tinitial

Calculate the joules of energy needed to warm 55g Al from 25oC to 79o C

Heat = (Sp.Ht.)(mass)( delta T)

= 0.908 J x 55g x(79oC - 25oC)   = 2696.76 = 2700 J
      goC       1              1
 

Heat always flows from a warm body to a cold body. The heat lost by the warm body equals that gained by the colder body. Heat lost is negative by convention because T = Tf - Ti < O.

A 60.0g Fe bar at 99.0oC is placed in

55.0 g H2O at 22.0oC. What is the final temperature.

- Heat Fe = + Heat H2O

- 0.444 J x (Tf - 99.0oC) x 60.0g  =  4.184 J x(Tf -22oC)x 55.02
         goC            1             1            goC            1             1

Tf = 30.0oC
 

Readme
Syllabus
Atomic Mass
Lec Notes 1-2
Hmwk Ch1-2
Lec Notes 3
Hmwk Ch3
Lec Notes 4
Hmwk Ch4
Lec Notes 5
Hmwk Ch5
Lec Notes 6
Hmwk Ch6
Lec Notes 7
Hmwk Ch7
Lec Notes 8
Hmwk Ch8
Lec Notes 9
Hmwk Ch9
Lec Notes 10
Hmwk Ch10
Lec Notes 12
Hmwk Ch12
Lec Notes 13
Hmwk Ch13
Formula Wrksht
Formula Ans
Equation Rules
Quantum No.s
Final Preparation
Exam 1T
Exam 3T
3T Answer Sheet
Dr. Plastas Main
MC Home