Chapter 1 - Chemistry and Measurement Flashcards
What is Chemistry?
the central science, everything depends on it
Give some examples of what chemistry has provided for us in the world
- better crop yields
- more nutritious food
-fuels - better health (medications)
What 3 phases does matter exist in?
Solid, liquid, gas
What are pure substances?
they have a fixed composition and have unique properties that can be used to identify a substance
ex: elements and compounds
What is a mixture?
composed of 2 or more pure substances in which each substance maintains its identity and they can be separated into their components
What is a homogenous mixture?
“solution” in which the composition is the same throughout
- if you split it into two bottles/pieces, the two pieces/bottles would have the same components
What is a solution
a solute dissolved into a solvent
What is the solute?
the substance being dissolved
ex: salt or sugar
What is the solvent?
the dissolving medium
ex: water (H20)
Give an example of a homogenous mixture
coffee, metal alloys (Brass, Bronze)
What is a heterogenous mixture?
mixture that is non uniform in appearance in which its composition varies throughout
ex: a rock, choc chip cookie, salad
What is filtration as a method of separating mixtures?
passing a mixture through fine pores to separate solid from a liquid
What is distillation as a method of separating mixtures?
separation of homogenous mixtures by boiling points (heat it up until one substance’s boiling point is hit)
What is chromatography as a method of separating mixtures?
separating a mixture by color (paper chromatography)
What are extensive properties?
dependent on the amount of the substance and cannot be used to identify a substance
ex: mass, volume
What are intensive properties?
independent of the amount of the substance and can be used to identify a substance
ex: boiling point, specific heat, density
What are physical properties?
properties than can be measured w/o changing the identity of the substance
ex: color, boiling point
What is density?
mass/volume, an intensive property made up of 2 extensive properties
ex: the difference between cake and cheesecake
What is solubility?
how much of a substance will dissolve in a specific amount of solvent at a specific temp
ex: KNO3 -> 32g/100g H20 @ 20 degrees C
Absorbance and Transmittance
a substance has a specific color due to its absorbance and transmittance of light
- the color is what is transmitted because it was not absorbed
What are chemical properties?
properties that can be determined only by changing the identity and composition of the substance
- destructive test is needed
ex: Flammability
nano- (n)
10^-9
pico- (p)
10^-12
What are the 2 things that accuracy is dependent upon?
- The measuring device
- The skill of the operator
What do significant figures express?
the degree of uncertainty (the margin of error)
Sig Fig Addition and Subtraction Rule
the answer cannot be more accurate than the least accurate number in the calculation
- no more decimal points than the number with the leat amount of decimal points
Sig Fig: 8.947 + 3.9 = ?
12.847 -> correct sig figs: 12.8
(ONLY 1 DECIMAL POINT)
Sig Fig Multiplication and Division Rule
the answer must follow the number in the problem with the least number of sig figs
Sig Fig: 42.8 x 1.1 = ?
47.08 -> correct sig figs: 47
(ONLY 2 SIG FIGS)
Sig Figs: If you divide 24.897 L of beer equally into 20 bottles, how much would be in each bottle?
24.897/20 = 1.24485 -> correct sig figs: 1.2449
- There are exactly 20 bottles (counted), exact numbers are assumed to have infinite sig figs
- so you follow the number of sig figs in: 24.897
milli- (m)
10^-3
micro- (µ)
10^-6
mega- (M)
10^6
kilo- (k)
10^3
centi- (c)
10^-2
deci- (d)
10^-1
