Chemistry Flashcards
Mass Percent (Weight Percent)
Mass Percent = grams of solute / (grams of solute + grams of solvent) * 100
Define Molarity
Molarity = moles of solute / liters of solution
Molality
m = moles of solute / kg of solvent
Parts per million
x/million = mass solute / (mass solute + solvent)
set up ratio and solve for X
chromatography
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.
Spectrophotometry
uses percent light absorbance to measure a color change, thus giving qualitative data a quantitative value.
Centrifugation
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.
Electrophoresis
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.
Specific gravity
ratio of the density of a substance to the density of water.
Ideal Gas Law
PV = nRT
Charles’ Law
relates Temperature and Volume as directly proportional
V1/T1 = V2/T2
Temp always in KELVIN!
Boyle’s Law
Pressure and Volume are inversely related:
P1V1 = P2V2
Combined Gas Law
P1V1/T1 = P2V2/T2
Avogadro’s Law
V = constant * n (moles)
the constant is usually R = .0821 or .08206
molar volume of an ideal gas
22.4L/mole
Density of ideal gas
formula weight / 22.4
Democritus
greek philosopher who first suggested the concept of the atomic theory of matter.
John Dalton
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
JJ Thompson
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.
Ernest Rutherford
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
Millikan
Oil drop experiment - found unit charge on electron is 1.6E-19
Neils Bohr
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.
Progression of electron shells
first (K shell) 2 e-
2nd (L shell) 8 e-
3rd (M shell) 18 e-
4th (N shell) 32 e-
metalloids
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
semiconductors
conduct electricity at high temperatures but not low temps (opposite of metals). Boron the first, followed by SILICON!
bonding strength strongest to weakest
covalent - ionic - metallic - hydrogen bonds (NOF) - dipole-dipole - dispersion (London, Van der Wahls)
Dalton’s Law of Partial Pressure
Ptot = P1 + P2 + P3 + … + Pn
Graham’s Law of Diffusion and Effusion
Rate of effusion g1 / rate of effusion g2 = √(FW2/FW1)
