Chem 111 Final Exam Flashcards
what is an advantage of BTB indicator?
BTB is more sensitive to acids and bases and shows a more obvious color change
describe the observations of OTO with tap water and Brita filter water
the activated charcoal in the brita filter reduced the chlorine in the water by 2 ppm, making it untraceable
what is the purpose of a discharge tube?
electrons are excited to certain levels so that only certain frequencies are produced
what is the fundamental reason why a substance absorbs visible light?
the radiation possesses the energy needed to move an electron from its lowest energy state to an excited state
what does a large retention volume mean?
more mobile phase must be used to flush the dye from the column
what is meant by small calorie ācā?
one small calorie is a scientific calorie, or the energy needed to raise the temperature of 1 g of water by 1 `C
write a reaction to explain why adding H2SO4 to Al caused bubbling
2 Al (s) + 3H2SO4 (aq) -> Al2(SO4)3 (aq) + 3H2 (g)
what is the specific heat of water?
4.18 J/g `C
explain the complementary nature of absorbed/observed colors
the color being observed is seen because the complementary color is absorbed
explain the difference between aluminum corrosion and iron corrosion
in aluminum corrosion, the top layer corrodes and forms a protective film that protects the rest of the metal; iron corrodes fully
define calorimetry
the study of the amount of energy released/absorbed during a chemical reaction
what is the effect of changing slit width on the spectroscope?
intensity is brighter when slit is wider; resolution is blurrier when slit is wider
how is absorption capacity calculated?
mass of CO2 absorbed/mass of absorbent used
describe the alum tests for SO4 2-, K+, Al 3+, and H2O
SO4 2-: BaCl2 added to form white precipitate
K+: falme test produced purple flame
Al 3+: adding KOH caused a white precipitate to form and then redissolve
H2O: sizzling sound during flame test
what does the melting point test tell us about the alum?
confirmed the identity of the alum; told us about the purity of the sample
to obtain good separation in chromatography, what must be minimized and maximized?
spreading area of each component minimized; migration differences of each component maximized
what process removes the energy from excited food dye molecules in aqueous solution?
energy is removed by solvent molecules bumping billions of times per second against the excited food dye molecules
what are uses for the alum compound?
the making of paper; the making of fire extinguishing compounds
define spectroscopy
spectroscopy is the study of the interaction of electromagnetic radiation with matter
what is meant by a food calorie?
one food calorie is 1000 scientific calories
write an equation that explains why carbonated beverages are acidic
CO2 (g) + H2O (l) -> H2CO3 (H+ and HCO3-)
what is retention volume?
volume of mobile phase needed to carry the solute through the column
write out the crystal drano alum synthesis reaction
Al2CO3 (s) + 2NaOH (aq) + 3H2O (l) -> 2NaAl(OH)4 (aq)
2Al (s) + 2NaOH (aq) + 6H2O (l) -> 2NaAl(OH)4 (aq) + H2 (g)
explain the difference between line spectra and continuous spectra
line spectra contain certain frequencies, while continuous spectra contain all frequencies
