General Chemistry I
1 - Introduction
of matter and the changes that matter can undergo
n Au, H2O,
point, color, vapor pressure
two categories of matter are an element or a compound (more later)
n Two types of properties to describe matter
n no rearrangement of the atoms
n atoms will rearrange to form new substances
be of any phase
BE SEPARATED BY PHYSICAL MEANS!
Problems 1, 3, 5
Elements and Compounds
- cannot be decomposed by CHEMICAL means.
blocks' of the universe
by symbols (Table 1.2 - know)
n Compounds - decomposed by chemical means to
of constant composition
samples of a compound will have the same elements in the same ratio
Problems 7, 9, 11, 13, 15
Units of Measurement.
n Metric system - basis for SI system
n Units based on measurements of Earth
n Meter based on distance from equator to North Pole
n Heat based on energy to change water
n SI system
n Divides units into ‘base’ and ‘derived’
n Seven ‘base’ units
n All other units are a combination of the ‘base’ units
of substance (mol)
other units - derived units
( length3 )
[ mass * length / time2 ]
( mass / volume )
decimal amount of unit
- unit x 1000
- unit x 0.01
prefixes from Terra to femto
both abbreviation and unit
base unit by 0.001
between MASS and WEIGHT.
is a base unit
is a derived unit (mass x acceleration)
will not change with change in the gravitational field, but an object may
- Celsius (non SI unit)
(freezing) to 100 (normal boiling) to define step size
'step size' as Celsius
point is absolute zero
= OC + 273.15
correct for starting point!
n English - Fahrenheit
n Different step size (180 OF from freezing to boiling)
n Different starting point (32 OF = 0 OC)
n Must make TWO conversions
n Step size
n Starting point
n OF =
[(180/100) x OC] + 32OF
n OF =
[(9/5) x OC] + 32OF
n Rearranging, (OF - 32OF) x (5/9)
unit was the Litre (L)
commonly used for volume
unit = dm3
- 0.001 L
Units of Measurement
D/N mean weight!!!
of a substance / density of water
to the density in g/mL
between mass and volume using the value for density
& Extensive properties
Problems 17 -29 odd
Uncertainty in Measurements
n Exact numbers - no uncertainty
n numbers 'by definition’
n ‘Counting numbers’
n Measurement - inexact numbers - ALWAYS
n Precision and accuracy
n NOT the same thing!
n I don’t care what Webster says!!
Precision and Accuracy
- comparison of values to each other
- comparison of values to a TRUE value
to indicate first uncertain digit
digits are significant
n Between s.f.- significant (108)
n Right of decimal
AND right of s.f. - significant (10.0)
n left of first s.f. ARE NOT significant. (0.0153)
n Left decimal and right s.f. - maybe
n 5 significant figures
n Because I said so!
scientific notation to clear up ambiguity
n X =
n Z -
Significant Figures in Calculations
number of significant figures in the calculation
significant’ decimal place
may contain too many significant figures after manipulation
do we fix this?
to make answer display the correct number of significant figures
from first non-retained digit
n 0-4 round down (108.4 = 108)
n 6-9 round up (107.7 = 108)
- round up
- round to the even
at the end of a calculation, not in the middle!
Problems 31 - 37 odd
factors - equal to 1 (no units)
use several sequentially
use to cancel in numerator or denominator
Problems 39-49 odd
among the three states of matter.
between physical and chemical properties, as well as physical and chemical
among elements, compounds, and mixtures.
the symbol for the elements in Table 1.2
the basic SI units, the common metric prefixes and their meanings.
temperature among OF, OC, and K.
calculations involving density.
the number of significant figures in a measured quantity.
the result of a calculation with the proper number of significant figures.
metric and English system measurements using dimensional analysis.