Organic Chemistry
Phase Changes
Intermolecular Forces
Solubility
Misc.
100
Atoms other than Carbon and Hydrogen
What are Heteroatoms?
100
Why does water vapor at 100C cause more severe burns than liquid water at 100C? Relate your answer to enthalpy for credit.
Water vapor, because it is at a higher energy state. Heat of Fusion --> Solid to liquid Heat of Vaporization --> Liquid to gas Heat of Fusion < Heat of vaporization Meaning that within the phase change the water in vapor form has absorbed more energy(endothermic).
100
What is the weakest intermolecular force? And how does that intermolecular force occur between molecules?
Dispersion. This force occurs when temporary dipoles are are introduced in non-polar molecules, and those non-polar molecules create a disturbance (another temporary dipole) in other near by non-polar molecules. (Think chain reaction)
100
Which member of each pair is more soluble in diethyl ether? a) NaCl(s) or HCl(g) b) H2O (l) or CH3COH(l) c) MgBr2(s) or CH3CH2MgBr(s) DAILY DOUBLE: If you can tell me the name of the organic catagory CH3CH2MgBr falls under.
a)HCl, because the dipole-dipole interactions of H-Cl better match the intermolecular forces of diethyl ether. b) H2O because it is capable of hydrogen bonding. c) CH3CH2MgBr, because the non-polar, ion interactions are more closely related to dipole-dipole than ionic bonding. Daily double: Organometallics
100
You want to convert among molarity, molality and mole fraction of a solution. You know the masses of solute and solvent and the volume of the solution. Is this enough information to carry out all the conversions? Explain
With just this information, you can convert between molarity and molality, but you need to know molar mass of solvent to convert to mole fraction.
200
What Structural feature is associated with each type of hydrocarbon: Alkane, Alkene, Alkyne, and cycloalkane? Give the general formulas: Which hydrocarbons are saturated/unsaturated?
Alkane = single bonds, C2nH2n+2, saturated Alkene = Double bonds, C2nH2n, unsaturated Alkyne = Triple bond, C2nH2n-2, unsaturated Cycloalkanes = single bonds, C2nH2n, saturated
200
Many heat-sensitive and oxygen sensitive solids, such as camphor, are purified by warming under vacuum. The solid vaporizes directly, and the vapor crystallizes on a cool surface. What phase changes are involved in this method?
Solid --> Gas = sublimation Gas --> Solid = deposition
200
What is the predominant intermolecular force in each of the following: a) CO2 b) H2SO4 c) CH3OH (l) in CCl4 (l) d) SO2
A) Dispersion/ London B) Hydrogen Bonding C) Dipole-induced-Dipole D) Dipole-Dipole
200
Use the following data to calculate the combined heat of hydration for the ions in potassium bromate (KBrO3): *Enthalpy of lattice = 745 kJ/mol *Enthalpy of solution = 41.1 kJ/mol
-704 kJ/mol
200
What is a chiral center? How can we determine chiral centers.
A chiral center is where a carbon is surrounded by 4 different groups. It has a tetrahedral geometry We can determine chiral centers by looking for the groups attached to each carbon.
300
Draw the structure of 3,3-methyl-4-ethyloctane
\ / /\/\/\/ /\
300
Warm-blooded animals have a narrow range of body temperatures, because their bodies have a high water content. Explain using properties of water.
Water has multiple unique characteristics, one of which is specific heat capacity. Because of the higher intermolecular forces, water can hold a large amount of energy as heat.
300
A) Define Polarizability. B) Which of the following has the greater polarizability: 1. Ca2+ or Ca 2. Br- or I- 3. CH2=CH2 or CH3CH3
Polarizability- How easily an electron cloud can be distorted. Polarizability: * increases down a group *decreases across a period * Cations are less polarizable than their parent atoms, because they are smaller. Anions are more polarizable than their parent atoms because they are smaller. 1. Ca 2. I- 3.CH2=CH2
300
State whether the entropy of the system increases or decreases in each of the following processes: 1. Gasloine burning in a car engine 2. Gold is extracted and purified from its ore 3. Ethanol dissolves in 1-propanol.
1. increasing 2. decreasing 3. increasing
300
What forces (inter/intra) are acting in each scenario: a. Those preventing oil from evaporation at room temperature. b. Those preventing butter to melt in the fridge. c. Those allowing silver to tarnish d. Those that prevent O2 from becoming O
a. inter b. inter d. intra c. intra
400
Each of the following names are wrong. Make necessary corrections. a) 4-methylhexane b) 2-methylcyclohexane c) 2-ethylpentane d) 3,3-methyl-4-ethyloctane
a) 3-methylhexane b) 1-methylcyclohexane c) 3-methylhexane d) 4-ethyl-3,3-dimethyloctane
400
What is the packing efficiency in a body-centered cubic units.
68%
400
Given the following information answer these questions: * compound A has a boiling point of 30C. Compound B has boiling point of 90C. Compound C has a boiling point of 50C. Compound D has a boiling point of 112C. A. Order in terms of increasing intermolecular force strength. B. Which compound has the highest VP at room temperature?
A. A
400
Calculate the molarity: 3.7 mols of (NaNH2) in 567 mL of (CH triple bond CH).
M= mols/L = 3.7/.567 = 6.5M
400
How many kids does professor Mao have?
3
500
A) Define cis/trans isomers. B) Which hydrocarbon type makes cis/trans isomers, and why don't the others? C) Give one example of a hydrocarbon that can form cis/trans isomers. D) Give one example (with the correct hydrocarbon type) that does not form cis/trans isomers.
A) Cis isomers are formed from priority groups being on the same side of the double bond. Trans isomers are formed from priority groups being opposite the double bond. B) Alkenes. Alkynes are linear and only bonded to two groups. There can be no comparison of groups, and no other possible structures. Alkanes are completely saturated and have too many groups. The tetrahedral geometry prevents groups for this orientation. C) CH3CH=CHCH2CH2CH3 D)(CH3)2C=CHCH2CH3
500
A liquid has a Heat of Vaporization of 31.5 kJ/mol at 131 degrees Celsius and 1atm. What is it's vapor pressure at 112 degrees Celsius?
0.63 atm
500
Pentanol has nearly the same molecular weight as hexane, but is more than 12 times as viscous at 20 degrees Celsius. Draw the structures of Pentanol and Hexane, then Explain.
Pentanol = \/\/\ OH Hexane = /\/\/ Pentanol is capable of H-bonding. As intermolecular forces get stronger, Viscosity increases. (Low vp, slower molecules at 20 degrees Celsius)
500
Calculate the molarity, molality, and mole fraction of NH3 in a 11.20 mass % aqueous solution. (d=0.9651 g/mL)
Molarity = 6.348 M Molality = 7.407 m Mole fraction = 0.1177
500
1. When you hear induced think _______ 2. You look for a ____ and a ______ in ionic bonding 3. You look for a ___,___, or, ___ with ___ pairs in H-bonding.
1. non-polar 2. Non-metal and metal 3. N,F, or O with lone pairs
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