OC-2019 Flashcards
Which of the following compounds has an Ionic bond?
I. H2O
II. NH4Cl
III. CH3Cl
IV. CH3Li
A. II
B. IV
C. I
D. III
II
electronegativity > 1.7 = ionic
How many hydrogen atoms are in one molecule of propene?
A. 4
B. 3
C. 6
D. 8
6
CnH2n
In which species are all the carbon atoms considered to be sp2 hybridized?
l. C2H2
II. C2H4
Ill. C3H8
IV. C4H10
A. IV
B. Il
C. I
D. Ill
II
Sp3 - alkane
sp2 - alkene
sp - alkyne
How many different compounds have the formula C5H12?
A. 5
B. 2
C. 4
D. 3
3
C5H12 - 3
C4H10O - 4
In which species Is the carbon-nitrogen bond the shortest?
I. CH3NH2
II. CH2NH
Ill. (CH3)4N+
IV. CH3CN
A. Il
B. I
C. IV
D. Ill
IV
Bond Order = Bond Strength = 1/Bond Length
Bond length is inversely proportional to the bond order
What Is the hybridization of the carbon atom in a carboxyl group?
A. sp
B. sp3
C. sp2
D. dsp3
sp2
Carboxyl - C double bond O
Sp2 = alkene
Functional Group:
Alcohol
Ether
Amine
Aldehyde
Ketone
Carboxylic Acid
Ester
Amide
REVIEW!!
Which of the following hydrocarbon has the lowest boiling point?
l. C4H10
ll. CH4
Ill. C6H6
IV. C2H6
A. IV
B. II
C. I
D. III
II
higher C atoms/cyclic = high BP
high molecular weight = high IMF = high BP
How many different alcohols have the molecular formula C4H10O?
A. 2
B. 4
C. 3
D. 5
4
Which compound Is expected to be most soluble in water at 25oC
I. N2 (g)
II. O2 (g)
Ill (C2H5)2NH (l)
IV. C2H5OC2H5 (l)
A. III
B. IV
C. I
D. II
III
- Protic [-OH, -NH, -FH]
- Aprotic [-O, -N, -F]
- Non-polar [O2, N2, CH4]
The gentle oxidation of ethanol (CH3CH2OH) produces ______
A. ethanal, CH3CHO
B. ethanoic acid, CH3CO2H
C. carbon monoxide, CO
D. carbon dioxide, CO2
ethanal
primary alcohol -> aldehyde -> carboxylic acid
secondary alcohol –> ketone
tertiary alcohol –> no reaction
The following compounds have very similar molar masses. What would be the correct order when they
are arranged in order of increasing strength of their intermolecular forces.
l. C3H8
Il. CH3OCH3
III. CH3CH2OH
A. II < I < III
B. III < I < II
C. I < II < III
D. III < II < I
I < II < III
Intermolecular Forces: HB > Dipole-dipole > Van der Waals
What is the position of the bromine atom relative to the methyl group in 3-bromotoluene?
A. meta
B. para
C. ortho
D. trans
meta
mono –> 1
ortho –> 1, 2
meta –> 1, 3
para —> 1, 4
Which combination of reactants produces an ester?
A. aldehyde and potassium permanganate
B. acid and alcohol
C. acid and aldehyde
D. alcohol and aldehyde
acid and alcohol
In crystallization, the solution which is obtained after filtration is the
A. clear solution
B. colloidal solution
C. suspended solution
D. None of the given answers
clear solution
In crystallization, the crystal phases can be Inter-converted by varying ______
A. temperature
B. pressure
C. viscosity
D. size
temperature
Which separation technique is based in the volatility of the compounds to be separated?
A. solvent extraction
B. distillation
C. paper chromatography
D. filtration
distillation
Fractional distillation is different from distillation because of the presence of a _______
A. Fractionating column
B. Condenser
C. Conical flask
D. Distillation flask
Fractionating column
A common measure of efficiency in a fractionating column is the
A. length of the condenser used in the setup
B. number of distillation types
C. number of components in the solution
D. number of theoretical plates in the column
number of theoretical plates in the column
Five grams an organic solid was dissolved in 100 mL of distilled water. Which of the following extraction
methods can remove the largest amount of organic solid from an aqueous solution?
A. Extract the aqueous solution with a 150-mL portion of ether.
B. Extract the aqueous solution with three 50-mL portions of ether.
C. Extract the aqueous solution with a 150-mL portion of acetic acid.
D. Extract the aqueous solution with three 50-mL portions of acetic acid.
Extract the aqueous solution with three 50-mL portions of ether.
Which of the following funnels should be used to filter hot mother liquor during recrystallization?
A. Buchner funnel
B. Hirsch funnel
C. Long stem funnel
D. Short stem funnel
Short stem funnel
short stem/stem less - hot gravity filtration
buschner funnel - suction/vacuum filtration
What is the key step in a recrystallization process?
A Taking the melting point of wet crystals
B. Dissolving the solid in a large quantity of cold solvent
C. Allowing the hot solution to cool slowly and let crystals grow
D. Removing the soluble impurities by vacuum filtration
Allowing the hot solution to cool slowly and let crystals grow
Which of the following is the example of crystallization process?
A. Purification of alum
B. None of the given answers
C. Separation of gases from air
D. Purification of sea water
Purification of alum
A constant boiling mixture of two in a solution is called a/an _______
A. azeotrope
B. Ideal
C. non-ideal solution
D. eutectic mixture
azeotrope
A compound Is known to decompose at its boiling point. Which of the following can be to purity this
substance?
A. Steam distillation
B. Fractional distillation
C. Liquid-liquid extraction
D. Vacuum distillation
Steam distillation
Which is the INCORRECT statement among the following?
A. An impure sample of the substance has a different melting point.
B. Two different pure substances have the same melting points.
C. Melting point serves as the criterion of purity of a solid substance.
D. Every pure crystalline substance has a characteristic and unique melting point.
Two different pure substances have the same melting points.
The boiling point of a liquid is the temperature at which the vapor pressure is ______
A. lesser than internal pressure
B. equal to internal pressure
C. equal to external pressure
D. greater than internal pressure
equal to external pressure
(usually atmospheric pressure pressure)
Which of the following statements is correct?
A. Solid reactants can be weighed directly in the weighing pan of the analytical balance
B. Weight of liquids is approximately equal to its density.
C. Solid reactants can be transferred to a reaction flask by using a metal spatula.
D. Volatile liquids can be weighed by getting the mass of the empty vial with cap first.
Volatile liquids can be weighed by getting the mass of the empty vial with cap first.
A reaction mixture needs to be cooled to -77•C after refluxing. What Is the best method to be used?
A. Place the reaction vessel in an ice bath.
B. Place the reaction vessel in the freezer.
C. Place the reaction vessel in a salt and crushed ice mixture.
D. Place tie reaction mixture in a dry ice-acetone mixture.
Place tie reaction mixture in a dry ice-acetone mixture.
• Ice bath: 0°C (maximum) • Freezer: -20°C • Salt and crushed ice mixture: -20°C
Which of reactions will consume the most oxygen?
A. complete combustion one mole of octane
B. complete combustion of one mole of 2,3-dimethylhexane
C. complete combustion of one mole of 2,3,4-trimethylpentane
D. All the given compounds win consume the same amount of oxygen.
All the given compounds win consume the same amount of oxygen.
(Determine the molecular formula of each compound and compare)