Unit 1 Flashcards
What is chemistry?
The study of matter and the changes it undergoes
What is matter?
Anything that has mass and takes up space
What is an atom?
Smallest amount of an element (ex. 1 gram of Copper)
What is a molecule?
Smallest amount of a compound (ex. 1 molecule of h20)
What is a compound?
A substance composed of two or more elements
What are the four states of matter?
Solid, liquid, gas, plasma
What is a pure substance?
An element or compound
What is a mixture?
A combination of two or more pure substances, or mixtures
What are components?
Pure substances within a mixture
What is a homogeneous mixture?
A mixture that is uniform throughout
What is a heterogeneous mixture?
A mixture that is not uniform throughout
What is a solution?
Homogeneous mixture
What is a phase?
A distinctly different region within a mixture
What is separation by inspection?
Usually only works for solids
What is filtration?
Does not work for solutions / homogeneous mixtures
What is distillation?
The process of heating a liquid to the boiling point, condensing the heated vapor by cooling and returning either a portion of, or none of, the condensed vapors to the distillation vessel
What is centrifigation?
Spinning a serum / liquid so the heavier stuff goes to the bottom
What is chromatography?
works with polar and nonpolar molecules and a solvent is pushed through to separate them through polarity
What is a property?
A characteristic that allows one substance to be distingushed from another
What is a physical property?
a characteristic that can be observed or measured without changing the identity of a substance (color, melting point, boiling point etc)
What is a chemical property?
describes the way a substance may react to another (ex, flammability oxidation)
What is an intensive property?
a property that does not depend upon the amount of the substance (ex. temperature, density, boiling point)
What is an extensive property?
a property that depends on the amount of matter in a sample (ex. mass, volume)
What is a physical change?
A change in which the form or appearance changes, but no new substances are formed
What is a chemical change?
when a substance changes chemically into another substance
What is a change of state?
the physical change from one state of matter to another. all changes are physical
S to L
melting
S to G
sublimation
L to S
freezing
L to G
vaporization / evaporation
G to L
condensation
G to S
vapor deposition
What is qualitative data?
a measure that is reported without a number and unit (ex. the coffee is hot, the barbell is heavy)
What is quantitative data?
a measurement reported with a number and a unit (ex. 13)
k, 10^3
kilo
d, 10^-1
deci
c, 10^-2
centi
m, 10^-3
milli
u, 10^-6
micro
n, 10^-9
nano
How to use prefixes?
Start with the prefix unit on the left and the base unit on the right
What is accuracy?
how close a measurement is to the true value
What is precision?
how close a series of measurements are to one another (repeatability)
What is a random error?
left and right of true value, no repeatability
What is a systematic error?
a consistent difference between the measured values and true values
What is a certain digit?
The numbers read from a measuring instrument
What is an uncertain digit?
a digit that must be estimated
What are significant digits?
all certain + one uncertain, also called significant figures or sig figs
How do you read a graduated cylinder?
bottom of the meniscus
Rule #1 for sig figs
non-zero numbers are significant (ex. 63.5 = 3 sig figs)
rule #2 for sig figs
zeros between nonzero digits are significant (ex. 1001 = 4 sig figs)
rules #3 for sig figs
Zeros at the beginning of a number are never significant (ex. 0.00506 = 3 sig figs)
rule #4 for sig figs
Zeros that appear to the right of a nonzero number in a measurement that has a decimal point are always significant (ex. 105.00 = 5 sig figs)
rule #5 for sig figs
When a number ends in zeros, but has no decimal point, the zeros are not significant (ex. 1000 = 1 sig fig)
What are two situations in which the number has an unlimited amount of sig figs?
A counting number (ex. 19 students, 40 pennies) and a defined number (ex. 60 seconds in 1 minute)
When doing word problems, what do you start with?
What’s not a question
Mass =
density x volume
volume =
mass/density
density =
mass / volume
density of h2o
1 g/mL
Boiling point of h2o
100 degrees Celcius
Freezing H2O
0 degrees C
Tf = (1.8) x (Tc) + 32
Celcius to Farenheit
Tc = (Tf - 32) / 1.8
Farenheit to Celcius
Tc = Tk - 273
Kelvin to Celcius
Tk = Tc + 273
Celcius to Kelvin
