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PCAT STUDY GUIDE: CHEMISTRY
PRACTICE TEST QUESTIONS
sp3 - ANSWER tetrahedral
4 single bonds for oxygen and nitrogen tetrahedral bent sp2 - ANSWER trigonal planar 120 1 double 2 single for oxygen and nitrogen trigonal planar linear sp - ANSWER linear 180 1 triple 1 single or 2 double formula for alkane - ANSWER CnH(2n+2) a organic molecule that contains at least one multiple bond is said to be__________ - ANSWER unsaturated boiling point - ANSWER the molecule with the most carbons will having the highest boiling point, unless it can hydrogen bond OH NH COOH. hydrogen bonding increases boiling point. organic compounds tend to be - ANSWER combustible neuclophile - ANSWER electron pair donor and hence a lewis base structural isomers - ANSWER known as constitutional isomers molecules that have a different bonding sequence stereoisomers - ANSWER molecules that have the same bonding sequence but different spatial orientation.
enantiomer-non-superimposable mirror images diastereomers-not mirror images-cis/trans a pure sample of each enantiomers (100%s and 100%r) is said to be - ANSWER optically active each pure enantiomer rotates the plane of polarized light by a certain number of degrees a 50:50 mixture of two enantiomers will NOT rotate the plane of polarized light is said to be - ANSWER optically inactive known as a racemic mixture in what order does SN2 reaction happen the fastest - ANSWER 1>2>3>unreactive in what order does SN1 reaction happen the fastest - ANSWER 3 >2>1 or methyl> unreactive racemitaztion occurs when center is a chiral carbon if one gram of a substance occupies 100oml and 4 gram of the same substance occupies 400 ml, then the substance is most likely to be - ANSWER gas which radiation has the least penetrating power? - ANSWER alpha toluene is most soluble in - ANSWER c6h6-like disolves like. toluene is a 6 membered ring with a methyl group if there are 3 electrons in 2p, the electrons will differ in - ANSWER magnetic quantum number (m1, orbital) which molecule with undergo an SN2 reaction the fastest? - ANSWER the molecule that is less sterically hindered the condition at which the solid state , the liquid state, and the gas state coexist in equilibrium is known as the - ANSWER triple point which of the following solutions would exhibit the lowest freezing point? 0.1 M HCl 0.1 M CH3COOH 0.1 M glucose 0.1 M NH3 - ANSWER 0.1 M HCl what statement regarding a reaction that exhibits zero order kinetics is true? - ANSWER an increase in temperature will increase the rate of the reaction. zero order usually means rate is dependant on temp.
an ester is formed by the reaction of an alcohol an a(n) - ANSWER acid the higher the KA value for acids - ANSWER the stronger the acid if the probes from an electric light bulb were dipped into solutions, which one of the solutions would light the bulb? - ANSWER sulfuric acid solution only electroytes will light the bulb which bond will be the most ionic? - ANSWER always choose a metal bonded to a non- metal exp: K-Cl the chemical properties of an element are best predicted by the - ANSWER number of protons EN difference for non-polar - ANSWER less then 0. EN difference for polar - ANSWER between 0.5-0. EN difference for ionic - ANSWER greatest difference water can - ANSWER react with an acid and accept a proton or donate a proton to a base an aq solution that is saturated with glucose is placed in contact with some old solid glucose; what best describes the resulting equilibrium? - ANSWER glucose molecules would be dissolving into solution at the same rate that glucose precipitates out of solution. equilibrium is opposite processes occuring at the same rate the atomic number and the mass number for each atom is conserved - ANSWER in ordinary chemical reactions only which atoms belong to the same element - ANSWER if the proton number match must be the same number a lipid is formed by the reaction of a(n) - ANSWER fatty acid and glycerol what statement is consistent with the pauli exclusion principle? - ANSWER no two electrons in the same orbital can have the same spin orientation. an orbital is best described as - ANSWER the volume of space centered on the nucleus that an electron is most probably found in.
to prepare 1 liter of 2m glucose solution - ANSWER mix two moles of glucose with enough water to yield 1 liter of solution silver chloride has a ksp value of 1.8x10^10. the solubility of silver chloride in water is best described as - ANSWER insoluable a small Ksp=insoluable what solution would yield the highest boiling point? - ANSWER choose the electrolyte that yields the most ions. exp KCl only yields 2 ions but K2SO4 yields 3 ions. what solution would turn blue litmus red? - ANSWER only acidic solutions pH=2 for example a solubility of salt A in a solution that already has salt B dissolved in it will - ANSWER decrease if salt B contains an ion that is common to salt A if phosphoric acid is H3PO4 then what is the formula for phosphorus acid? - ANSWER H3PO
- ous always one less Oxygen then - ic N2+ 3H2<-----> 2NH if the volume of the container were suddenly doubled, which would be observed? - ANSWER moles of H2 would increase since increase in volume will shift towards side with more moles of gas diatomics - ANSWER H2, N2, O2,F2,Cl2,Br2,I the rate law for a particular reaction is Rate=K[A]^2[B]. if the particular run of this reaction, the concentration of A were doubled over what it had been in the previous run, while the concentration of B were halved, what would be the effect on the rate? - ANSWER the rate would double the mass spectrometer can be used to - ANSWER separate isotopes the law of multiple proportions is illustrated by which pairs of compounds? - ANSWER Na2O/NaOH same element but different ratios a o.1 M NaCl solution would have a pH of - ANSWER 7 NaCl is a neutral salt to get the conjugate acid - ANSWER add 1 H+
what type of reaction will most likely produce water and a salt? - ANSWER neutralization example hcl(aq)+NaOH(aq)--> H2O(l)+NaCl(aq) the boiling point of n-octane is 126 degrees C. what is the expected boiling point of n- nonane? - ANSWER 146 - 156 degrees C the boiling point increases with molecular weight by approx. 20-30 degrees for each additional carbon. how to choose an example of a synthesis reaction - ANSWER a synthesis reaction is a chemical reaction in which two or more substances combine to form a more COMPLEX substance. SO3(g) +H2O(l)--> H2SO4(aq) the nucleic acid that carries amino acids to ribosomes is - ANSWER transfer RNA during protein biosynthesis, transfer RNA transports appropriate amino acid dictated by genetic code to the ribosome for peptide bond formation. a sample of neutral argon is at certain temp and pressure. if the pressure is decreased enough to cause sublimation, the sample is now a - ANSWER gas sublimation-solid to vapor without passing through liquid phase. which class of organic molecules has neither nucleophilic nor electrophilic centers? - ANSWER straight-chaned alkanes alkenes,alkynes, aromatics represent high electron density and there for neucleophillic centers. ethanol C2H6O has a higher molar heat of vaporation then n-butyl chloride C4H9Cl because - ANSWER ethanol has stronger intermolecular forces. ethanol has more hydrogen bonds which leads to higher intermolecular forces. chemical structure of a cholesterol - ANSWER a bunch of octagons with oh and double bonded c=o. fatty acid-skeleton chain with lots of hydrogen carbohydrate-looks like sugar molecule (glucose, fructose)
choosing which molecule will have the highest melting point - ANSWER look to see if the molecule will hydrogen bond. if both will, then choose the one with the higher molar mass. which isotope, with the nuclear composition given, is most likely to be unstable and radioactive? - ANSWER choose the option with the highest ratio example H(1p+,3n0) this has a 1:3 ratio of p:n He is a product of radioactive decay (alpha particle) but is not radioactive Li is chemically reactive but not radioactive. which compound is most soluble in water? - ANSWER choose the option that is polar. like dissolves like ch3ch3OH what could be the unknown alcohol that reacted with KMnO4 to form caboxylic acid - ANSWER choose the structure with a primary alcohol such as 2-Methyl- 1 - butanol primary OH- carboxylic acid secondary OH-oxidize to ketones tertiary OH-are not oxidized by KMnO in hydrocarbons, carbon atoms usually form - ANSWER four covalent bonds C-H carbon can form 4 covalent bonds! the solubility product Ksp for AgCl in waer is 1.7x10^-10. what is the solubility in moles per liter of AgCl? - ANSWER solubility is defined as the number of moles of substance per liter of solution. to find the solubility ksp=[Ag+][Cl-]=x^2 therefore the ANSWER s √1.7x10^-10 (symbol is a square root) what compound is the product of the reaction butene with H2 and nickel catalyst - ANSWER butane this is hydrogenation, where hydrogen becomes added across the double bond of butene to form butane.
in order to increase the melting point of linear hydrocarbon to make candy, what approach would be best utilized? - ANSWER increasing the hydrocarbon chain length adding additional hydrocarbons will require more energy to break those bonds, therefore increasing the melting point. hydrolysis of fats forms what type of product? - ANSWER acids fats are solid at room temp, and fats that are liquid at room temp are called oil. tricylglyerol contains 3 fatty acids each linked to one of the three carbon atoms of glycerol. upon hydrolysis, a free fatty acid is produced, hence acid would be correct. what other reagent could be used instead of NaBH4 to perform a reduction reaction? - ANSWER LiAlH4 can be used to reduce a ketone. what will the molecule look like if hydrolysis is not avoided in a grignard reagent? - ANSWER it will form an alkane peroxides-if in the presence of oxygen gas alcohols-only if ketones or aldehydes are used as starting materials. if a compound has high melting point and is insoluble in a non-polar compound, then - ANSWER it is ionic covalent compounds-low melting point and soluble in non-polar compounds changes in cell membrane fluidity are often achieved through alteration of the number of double bonds in which molecule? - ANSWER phospholipids the fluidity of the membrane is dictated by how tightly the fatty acid of the phospholipids packs together. the looser the packing, the more the fluidity. the dehydration of two amino acids results in - ANSWER dipeptide
