Dimensional
Analysis
USING UNITS TO SOLVE A MATH PROBLEM
Dimensional Analysis
Using conversion factors to convert between units.
Multiply by a fraction that equals 1 to change units
2/2 = 1
12 inches / 1 foot = 1
How to use
Identify the given and the unkn
Unit 2Part 2 Notes
Dimensional Analysis
a method of problem solving in which units are carried through all
calculations
ensures that the final answer of a calculation has the desired units; units get
multiplied together, divided into each other, or cancel
SCIENTIFIC NOTATION
A WAY OF WRITING VERY BIG AND VERY SMALL NUMBERS
M X 108
M is the mantissa
M X 108
M is the mantissa
8 is the exponent
HOW TO WRITE A NUMBER IN SCIENTIFIC
NOTATION
Move the decimal between the 1 st and 2nd sig
fig
This will give you
All certain values (from
graduations) and one
estimated value (from space
between)
The precision of an instrument
is indicated by the number of
significant digits (sig figs)
67.4 mL
mL
81.2 mL
2.36
1.All none zero digits are
significant.
EX: 275.68 g =
QUALITATIVE
non-numeric description (big, small, pinch, etc)
QUANTITATIVE
EVERY MEASUREMENT MADE QUANTITATIVELY
MUST HAVE A NUMBER AND A UNIT.
ESTABLISHED 1960 BY INTERNATIONAL
AGREEMENT.
1)
2)
3)
4)
5)
6)
7)
LENGTH = METER (m)
MASS = KILOGRAM (
MATH with SIG FIGS
MATH WITH SIG FIGS
Sig figs help you round your
answer with correct precision
An answer can only be as
precise as your least precise
measurement.
MULTIPLICATION / DIVISION
Round the final answer off to the
measurement with the least
Metric System
Measurement System in
Science
The Metric System
A decimal system (based on
units of 10)
AKA System International
(SI)
Basic Units of Measurement
Length - Meter (m)
Volume - Liter (L)
Mass - Gram (g)
Time Second (s) or (sec)
Changing th
Use the decimal method to solve
4 mL = _L
1
Copy the number and box in the
sig figs
200
2
Use the decimal method to solve
1.5 dm = _mm
3
Copy the number and box in the
sig figs
802.5
4
Round each number to the number
of sig figs listed
802.5
3 sig figs
5
Name _
Hour _
Show boxes for each.
1000 cl = _ L
120 mm = _ cm
200 cl = _ L
2 cm = _ mm
11000 L = _ kl
10 cl = _ ml
12000 m = _ km
8 g = _ cg
80 ml = _ cl
3 L = _ cl
2000 L = _ kl
5 cm = _ mm
4000 ml = _ L
11 cg = _ mg
900 cm = _ m
9000 m = _ km
7000 ml =
Name _
Hour _
Working With Numbers: Sig Figs
Complete the following statements by adding are or are not in the blanks provided.
1.
2.
3.
4.
Zeros between two significant digits _ significant.
Zeros to the right of a decimal point that precede all nonzero
Name _
Hr _
Give the number of significant figures in each of the following.
1.05 g _
0.0003040 mm _
29000 ft _
0.90 _
Determine the answer for each of the following. Be sure to use the correct number of significant
figures.
a) 17.34
4.900
+ 23.1
b)
9.80
Name _
Show all work
Desk_
Hour _
Table of Weights and Measures
Length
1 nautical mile=6076.11549 feet
1 inch = 2.54 cm
1 league = 5 280 yards
1 cable = 120 fathoms
1 fathom = 6 feet
1 degree = 69.047 miles
1 mile = 5280 feet
1 hand = 4 inches
Area
1 town
Dimensional Analysis Worksheet #2
1. 261 g kg
12. 0.74 Kcal/min to cal/sec
2. 3 days seconds
13. 1.42 g/cm2 to mg/mm2
3. 9,474 mm cm
4. 0.73 kL L
5. 5.93 cm3 m3
14. 10095 m/s to miles/s
15. 9.81 m/s2 to ft/s2
6. 498.82 cg mg
16. 8.41 g/mL to Kg/L
7. 1 ft3
Math with Sig Figs
12. Perform each of the following calculations and express all answers in the correct number of
significant figures:
a. 4.07 g + 1.863 g
b. 3127.55 cm 784.2 cm
c. 0.067 mL + 1.01 mL 2.5 mL
d. 36.427 m + 12.5 m + 6.33 m
13. Perform each
Significant Figures Worksheet
How many significant figures are in each of the following numbers?
1)
5.40 _
6)
1.2 x 103 _
2)
210 _
7)
0.00120 _
3)
801.5 _
8)
0.0102 _
4)
1,000 _
9)
9.010 x 10-6 _
5)
101.0100 _
10)
2,370.0 _
11)
Why are significant figures
EMPIRICAL
FORMULAS
FORMULAS WITH THE LOWEST WHOLE NUMBER
MOLE RATIO OF ATOMS IN A COMPOUND
HOW TO CALCULATE
All units must be in moles
% Composition or sample masses are used to
determine the ratio of elements in the compound
Before you begin, turn all %
1
Unit 8 - The Mole and Avogadros Number
By the end of this unit you should be able to:
Interpret a formula and calculate its mole weight
Convert between the units of grams and moles
Calculate the number of molecules or atoms in a given amount of subst
Unit 8 review
1
Whats the empirical formula of a
molecule containing 18.7% lithium,
16.3% carbon, and 65.0% oxygen?
2
Whats the molecular formula for the
last problem if the molar mass of the
compound is 295.2 grams/mole?
3
How many molecules are there in
Unit 8 Test Review: The Mole and Avogadros number KEY
1. 42.9 g O2
11. CH3O
2. 2.6 x 1024 molecules H202
12. X3Y
3. 58.3 g/mol
13. Empirical Formula CHO
4. 1360 g Ar
Molecular Formula C4H4O4
-21
5. 4.26 x 10 grams
14. Empirical Formula C3H3O
6. 1.78 x 102
THE MOLE
The amount of a substance containing
a specific # of particles
Similar to words like dozen, gross, etc
MOLE WEIGHT
a.k.a molar mass
calculated the same as formula
weights, except the unit is the
gram/mole
EXAMPLE
Oxygen
Fw: 2(16.0 u) = 32.0
Acid Nomenclature Worksheet
Name _
This side must be completed before leaving today
Write the formula for each of the
acids listed below:
Name each of the following acids:
1. Nitric acid
1. HClO4
2. Chloric acid
2. H3PO4
3. Hydrobromic acid
3. HCl (aq)
4.
Unit 7 Part 2: Naming and Formula Writing
By the end of this unit you should be able to:
Calculate the % composition of a substance
Name and write formulas for ionic compounds
Name and write formulas for covalent compounds
Write the formula/name for the
Name _
Date _
I.
Title: PERCENTAGE COMPOSITION A HYDRATE
Lab partner _
II.
Purpose: Determine the percent of water in the hydrate, copper (II) sulfate pentahydrate.
III.
Materials and apparatus: Evaporating dish, 2 g copper (II) sulfate pentahydrate (CuSO
Percentage of Sugar in Bubble Gum
Purpose
To determine the
percentage of sugar
in bubble gum.
Materials
balance, bubble gum
Procedure
Note: Chewed gum cannot be placed directly on the balance pan; it must
be wrapped in paper and the mass of the paper subt
In this activity students are given a tag (or necklace) to wear with the symbol of an ion and its
oxidation number. Positive ions are green and the negative ions are blue. The students are instructed
to "bond" with other ions and keep a record of their bo
Name _ Section _ Row _ Hour _
Bond with a Classmate
When you find another ion with which you can bond, write in each symbol and charge.
Then write the new compound formed by combining the two. Give the compounds name. Remember
Positive ions can only bond
Student # _
Name: _
Hour _
Bond with a Classmate
When you find another ion with which you can bond, write in each symbol and charge.
Then write the new compound formed by combining the two. Give the compounds
name. Remember Positive ions can only bond wit
PERCENT
COMPOSITION
HOW TO CALCULATE
1)
Calculate the formula weight of the
compound
2) Calculate the weight of each
element in the compound
% = WT. OF SAMPLE
WT. OF COMPD.
X 100
EXAMPLES
FeSO4
FORMULA WT:
151.9 u
55.8u + 32.1u + 4(16.0u)=
% COMPOSIT
Formula Writing &
Naming
Unit 7-Part 2
Formulas
Shorthand way of representing a
compound
Types:
Structural
Molecular
Empirical
Molecular Formula
Shows # and kinds of each atom in the
compound
Uses symbols and subscripts
Overall charge: zero (neutr
FORMULA
WEIGHTS
WEIGHT OF A MOLECULE, FORMULA UNIT OR ATOM
HOW TO CALCULATE
Look at the formula
Look up masses of elements on periodic table
(round off to 1 digit after the decimal tenths
place)
Multiply atomic masses by appropriate subscripts
from the