Organic Chemistry Click to start Question 1 How many structural isomers are possible with the...
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Transcript of Organic Chemistry Click to start Question 1 How many structural isomers are possible with the...
Organic Chemistry
Click to start
Question 1
How many structural isomers are possible with the molecular formula C6H14?
4 6
75
Wrong Answer!
Question 2
Which formulas represent butane or its isomer?
I. CH3 (CH2)2CH3
II.CH3CH (CH3)CH3
III.(CH3)3CH
I, II and III I and III only
II and III onlyI and II only
Wrong Answer!All structures are valid and have the molecular formula C4H10.
Question 3
Blur Professor Sim intends to create PVC through polymerisation but does not know which monomer to use. Which homogolous series would be appropriate?
Alcohols Carboxylic acids
AlkenesAlkanes
Wrong Answer!Alkenes and substituted alkenes readily undergo addition reactions by breaking one of the double bonds. They can be joined together to form polymers.
Question 4
Excess ethane was burnt in a closed system. Which of the following is not a possible product?
Water Carbon monoxide
SootCarbon dioxide
Wrong Answer!Incomplete combustion of hydrocarbon produces carbon monoxide, water and soot.
Question 5
What is the organic product of the reaction between ethanol and ethanoic acid in the presence of concentrated sulfuric acid?
CH3CHO CH3COOCH3
CH3COOCH2CH3CH3CH2COOCH3
Wrong Answer!The product is an ester, ethyl ethanoate.
Question 6
Which compound is a member of the aldehyde homologous series?
CH3CH2COCH3 CH3CH2CHO
CH3CH2COOHCH3CH2CH2COH
Wrong Answer!Aldehydes contain the –CHO functional group.
Question 7
What type of alcohol is 2-methylpropan-2-ol?
an unsaturated alcohol
a tertiary alcohol
a primary alcohola secondary alcohol
Wrong Answer!It is a tertiary alcohol, C(CH3)3 or CH3C(CH3)2-OH
Question 8Which of the following descriptions can be correctly applied
to the homologous series of alkanes?
I. Members of the series have the general formula CnH2n+2
II. Members of the series have similar chemical properties.
III.Members of the series are isomers of each other.
I only II only
I and III onlyI and II only
Wrong Answer!The members of a homologous series are not isomers of each other, other statements are correct.
Question 9
Which compound is an ester?
CH3CH2COOH C2H5OC2H5
HCOOCH3C3H7CHO
Wrong Answer!It contains an ester linkage: -COO-
Question 10
Which one of the following is the best method of distinguishing between an alkane and alkene?
Test with universal indicator
Burn the gases in excess oxygen
Add bromine waterTest their solubility in water
Wrong Answer!Alkenes rapidly react with bromine water via addition reaction.
Question 11
What is the name of the compound whose condensed structural formula is CH3CH2CH2COOCH3?
butyl methanoate methyl butanoate
pentanonemethyl propanoate
Wrong Answer!The compound is an ester formed from butanoic acid (see first part of the structure) and methanol (see seoncd part of the structure); therefore it is methyl butanoate.
C13H28
Question 12
A gaseous hydrocarbon, X, decolorizes aqueous bromine.Which one of the following molecular formulas could be X?
C2H4 C6H14
C10H20
Wrong Answer!C6H14 and C13H28 are both alkanes, C2H4 and C10H20 are both alkenes, but only C2H4 is a gas at room temperature.
Question 13
What is the function of sunlight during the reaction between chlorine and methane?
To dissociate the chlorine molecules into atoms.
To dissociate the chlorine molecules into ions
To break the C-H bonds in the methane molecule.
To increase the temperature of the mixture.
Wrong Answer!Light is a form of energy and is absorbed by chlorine molecules to dissociate the covalanet bond between the two chloribe atoms. Homolytic fission occurs:
Cl2(g) 2 (g) Cl
Question 14
What is the IUPAC name for (CH3)2C(OH) CH2CH3?
pentan-3-ol 2-methylbutan-2-ol
4-methylbutan-3-ol3-methylbutan-3-ol
Wrong Answer!There are 4 carbon atoms in the longest unbranched chain. There is a methyl group and an –OH group on the second carbon atom.
Question 15How do the bond angles and bond lengths in ethane and
ethene compare?
H-C-H bond C-C bond
angle in ethane length in ethane
larger longer
smaller longer
larger shorter
smaller shorter
Wrong Answer!The bond angle in ethane is smaller, 109.50 compared to 1200 , bond length in ethane is longer as the bond is just a single C-C bond, whereas there is a C=C bond in ethene.
Question 16
Which equation represents the combustion of methane in excess oxygen?
CH4(g) + O2(g) C(s)+2H2O(g)
CH4(g) + O2(g) CO2 (g)+2H2(g)
CH4(g) + 2O2(g) CO2 (g)+2H2O(g)
2CH4(g) + 3O2(g) 2CO (g)+4H2O(g)
Wrong Answer!Carbon dioxide and water are formed by complete combustion of a hydrocarbon.
Question 17
When the compounds below are listed in order of decreasing boiling point (highest to lowest) what is the correct order?
1. ethane 2. chloroethane
3. ethanol 4. ethanoic acid
2, 1, 3, 4 4, 3, 2, 1
3, 4, 1, 24, 3, 1, 2
Wrong Answer!Ethanoic acid and ethanol form stronger hydrogen bond, chloroethane and ethane molecules are bonded by weak van der Waals forces.
Stronger bonds -> Higher boiling point since greater amount of energy is needed to break the bonds.
The order of bond stength is
Ethanoic acid > ethanol > chloroethane > ethane
Hydrogen bonds ------------------------van der Waals forces
Question 18
The compound which is expected to have the lowest boiling point at a pressure of one atmosphere is:
CH3CH2CH2F CH3CH2COOH
CH3CH2CH2NH2CH3CH2CH2OH
Wrong Answer!The molecules will only have van der Waals’ forces acting between them, other examples have the capbility of hydrogen bonding between the molecules.
Question 19
Which products can be potentially obtained from crude oil and are economically important?
I. Plastics
II. Margarine
III.Motor fuel
I and II only I and III only
I, II and IIIII and III only
Wrong Answer!
Question 20
Which statement is correct about the reaction between methane and chlorine?
It involves heterolytic fission and radicals
It involves heterolytic fission and ions
It involves homolytic fission and ions
It involves homolytic fission and radicalsCl
Cl
Cl
Cl
Wrong Answer!The bond between the 2 chlorine atoms in Cl2 is weaker than C-H or C-C bond in CH4 and can break homolytically in the presence of UV to form 2 free Cl radicals.
1-chlorobutane
Question 21
Which product is formed when hydrogen chloride is added to but-2-ene?
2-chlorobutane 2,3-dichlorobutane
1,2-dichlorobutane
Wrong Answer! Cl H
HCl + H3C-C = C-CH3 H3C – C – C – CH3
H H H H
Question 22
The oxidation of propan-2-ol, CH3CH(OH)CH3, by sodium dichromate(VI) leads to the formation of:
Propanone, CH3COCH3
Propan-1-ol, CH3CH2
CH2 OH
Propanoic acid, CH3CH2 CO2H
Propanal, CH3CH2CHO
Wrong Answer!Oxidation of secondary alcohol forms a ketone.
Congratulations!