Chemistry

Question 0

Mass Percent (Weight Percent)

Answer 0

Mass Percent = grams of solute / (grams of solute + grams of solvent) * 100

Question 1

Define Molarity

Answer 1

Molarity = moles of solute / liters of solution

Question 2

Molality

Answer 2

m = moles of solute / kg of solvent

Question 3

Parts per million

Answer 3

x/million = mass solute / (mass solute + solvent)

set up ratio and solve for X

Question 4

chromatography

Answer 4

uses the principles of the capillary effect to separate substances such as pigments. Larger molecules move slower, and less as far up the paper whereas the smaller molecules will travel faster/further. This produces lines of different colors from a mixture of pigments.

Question 5

Spectrophotometry

Answer 5

uses percent light absorbance to measure a color change, thus giving qualitative data a quantitative value.

Question 6

Centrifugation

Answer 6

involves spinning substances at a high speed. The more dense part of a solution will collect at the bottom of the tube. Used to separate suspensions such as blood.

Question 7

Electrophoresis

Answer 7

Uses electric charge to pull electrically charged molecules (DNA mostly) through a gel to the positive side of the plate. The longer pieces will travel less distance while the shorter ones will travel further. A dye in the molecules will make them visible to note where they stop.

Question 8

Specific gravity

Answer 8

ratio of the density of a substance to the density of water.

Question 9

Ideal Gas Law

Answer 9

PV = nRT

Question 10

Charles’ Law

Answer 10

relates Temperature and Volume as directly proportional

V1/T1 = V2/T2

Temp always in KELVIN!

Question 11

Boyle’s Law

Answer 11

Pressure and Volume are inversely related:

P1V1 = P2V2

Question 12

Combined Gas Law

Answer 12

P1V1/T1 = P2V2/T2

Question 13

Avogadro’s Law

Answer 13

V = constant * n (moles)

the constant is usually R = .0821 or .08206

Question 14

molar volume of an ideal gas

Answer 14

22.4L/mole

Question 15

Density of ideal gas

Answer 15

formula weight / 22.4

Question 16

Democritus

Answer 16

greek philosopher who first suggested the concept of the atomic theory of matter.

Question 17

John Dalton

Answer 17

matter is made up of atoms
atoms of one element are similar to each other
atoms of different elements are different from each other
atoms combine to form compounds with new/different properties

Question 18

JJ Thompson

Answer 18

plumb pudding model - Cathode ray tube experiment - rays bent in electric and magnetic field.
Conclusion: atoms are made of positive and negative particles mixed evenly together.

Question 19

Ernest Rutherford

Answer 19

Gold foil experiment - discovered atoms are mostly empty space
center is positively charged and most massive part
electrons outside the nucleus in planet-like orbit
electrons and protons balance each other

Question 20

Millikan

Answer 20

Oil drop experiment - found unit charge on electron is 1.6E-19

Question 21

Neils Bohr

Answer 21

Orbiting electrons occupy specific energy levels. Electrons give off light quanta when moving from high energy to low energy, shown as a band of the spectrum.

Question 22

Progression of electron shells

Answer 22

first (K shell) 2 e-
2nd (L shell) 8 e-
3rd (M shell) 18 e-
4th (N shell) 32 e-

Question 23

metalloids

Answer 23

appear like metals
white or grey, not shiny
conduct electricity, but not as well as metal
some characteristics of metals and nonmetals both
properties don’t follow a pattern, forcing independent study of each

Question 24

semiconductors

Answer 24

conduct electricity at high temperatures but not low temps (opposite of metals). Boron the first, followed by SILICON!

Question 25

bonding strength strongest to weakest

Answer 25

covalent - ionic - metallic - hydrogen bonds (NOF) - dipole-dipole - dispersion (London, Van der Wahls)

Question 26

Dalton’s Law of Partial Pressure

Answer 26

Ptot = P1 + P2 + P3 + … + Pn

Question 27

Graham’s Law of Diffusion and Effusion

Answer 27

Rate of effusion g1 / rate of effusion g2 = √(FW2/FW1)