Unit 1 Flashcards
chemistry
the science that deals with matter and the changes that matter undergoes
matter
the materials of the universe
chemical change
where one or more substances become different substances
scientific method
observation
qualitative
quantitative
can be witnessed/recorded
qualitative observation
doesn’t involve a number
color, odor, appearance
quantitative observation
involves a # (mass, volume) & units
measurement
hypothesis
possible explanation for the observations
experiment
test hypothesis
theory/model
once we have hypothesis that agrees w/ observations
a set of tested hypotheses that explains some part of nature
why?
an interpretation of the behavior of nature
change as more info becomes available
law of conservation of mass
the total mass of materials involved is the same before and after a chemical change
natural law
generally observed behavior as statement
often see that same behavior applies to many diff systems
Ex: law of conservation of mass
law
a summary of observed behavior
what?
scientific notation
method used to make writing very large/very small #’s more compact & easier to use
units
define the scale of measurement being used
English system
mass - lb
length - ft
time - s
temp - F
SI system
mass - kg
length - m
time - s
temp - K
metric prefixes
Good Mornings kan definitely call me my name
giga, G, 109
mega, M, 106
kilo, k, 103
deci, d, 10-1
centi, c, 10-2
milli, m, 10-3
micro, µ, 10-6
nano, n, 10-9
volume
the amount of space that an obj occupies
metric - liter (L)
SI - m3
in lab, milliliter (mL) = cm3 (cc)
mass
quantity of matter in an obj
SI - kg
in lab, gram(g)
certain digits
always the same
uncertain digits
estimated & may vary
significant figures
’s recorded in a measurement
determined by uncertainty of the measurement
do: nonzero, captive 0’s, trailing 0’s (if decimal)
infinite: exact & counted #’s
don’t: conversion factors, sci notation, leading 0’s
rounding off
carry all digits until final calculation
if first insignificant digit is 5+, up; -5, down
NOT sequential
sig fig multiplication/division
use # of sig figs in limiting term
limiting term
the measurement w/ the smallest # of sig figs or decimal places
sig fig addition/subtraction
smallest # of decimal places
accuracy
how close the measurement is to the true value
precision
a measure of how close the measurements r to each other
equivalence statement
defines the relationship b/w diff units
Ex: 1 kg = 2.205 lbs
conversion factor
a ratio of the 2 parts of an equivalence statement that relates the 2 units
Ex: 1kg/2.205lbs
dimensional analysis
the process of converting from 1 unit to another
choose conversion factor that cancels the units u don’t want
when cubing/squaring, make sure to cube/square the WHOLE conversion factor
Kelvin
absolute temp scale
doesn’t use degree notation, just K
temperature conversion
C - K = C + 273
K - C = K - 273
F - C = (F-32)/1.8
C - F = 1.8(C) + 32
extensive property
depends on quantity of sample measured
mass, volume
intensive property
independent of sample size
prop’s often characteristic of substance being measrued
Ex: density, temp, melting & boiling pts
density
D = m/v
g/cm3 or g/mL
