Alkane
Multiple Choice: Which of the following is the general formula for alkanes?
A) CnH2n
B) CnH2n+2
C) CnH2n-2
D) CnH2nO
B) CnH2n+2
Multiple Choice: What type of reaction is used to make polymers from alkenes?
A) Condensation polymerization
B) Addition polymerization
C) Esterification
D) Oxidation
B) Addition polymerization
Multiple Choice: What is the functional group present in alcohols?
A) -COOH
B) -COO-
C) -OH
D) -C=C-
C) -OH
Short Answer: State the name of the carboxylic acid formed when ethanol is oxidized by microbial action.
ethanoic acid
Short Answer: Name the two types of organic compounds that react together to form an ester.
alcohol and carboxylic acid
Multiple Choice: Which statement about the combustion of alkanes is correct?
A) They burn in oxygen to produce carbon monoxide and water only.
B) They are unreactive and do not burn.
C) They burn in oxygen to produce carbon dioxide and water.
D) They require a catalyst to burn.
C) They burn in oxygen to produce carbon dioxide and water.
Multiple Choice: The test for an alkene involves shaking it with bromine water. What is the correct observation?
A) The bromine water turns from orange to green.
B) The bromine water remains orange.
C) The bromine water turns from brown to colorless.
D) The bromine water turns from orange to colorless.
D) The bromine water turns from orange to colorless.
Multiple Choice: Fermentation is a method used to produce ethanol. Which conditions are required for this process?
A) Aerobic conditions and a temperature of 30°C
B) Anaerobic conditions and a temperature of 30°C
C) Aerobic conditions and a temperature of 100°C
D) Anaerobic conditions and a temperature of 0°C
B) Anaerobic conditions and a temperature of 30°C
Short Answer: Describe a chemical test to show that a compound is a carboxylic acid. Include the reagent, observation, and a word equation for ethanoic acid.
Reagent: Sodium carbonate (or calcium carbonate). (1 mark)
Observation: Effervescence (fizzing) / bubbles of gas produced. (1 mark)
Word equation: Ethanoic acid + sodium carbonate → sodium ethanoate + water + carbon dioxide.
Ethyl ethanoate is an ester. Draw its displayed formula showing all atoms and bonds.
Displayed formula should show the ester linkage (C-O-C=O). Correct structure is CH3COOCH2CH3
Multiple Choice: Crude oil is a mixture of alkanes. Which process is used to separate crude oil into fractions with different boiling points?
A) Cracking
B) Polymerization
C) Fermentation
D) Fractional distillation
D) Fractional distillation
Multiple Choice: The industrial production of ethanol from ethene requires steam, a catalyst, and specific conditions. What is the catalyst used in this hydration process?
A) Concentrated sulfuric acid
B) Phosphoric acid
C) Yeast
D) Potassium dichromate(VI)
B) Phosphoric acid
Multiple Choice: When ethanol is heated with acidified potassium dichromate(VI), a color change is observed. What causes this color change?
A) The formation of Cr^{3+} ions
B) The formation of Cr_2O_7^{2-} ions
C) The formation of Cr^{6+} ions
D) The formation of carbon dioxide
A) The formation of Cr^{3+} ions
Short Answer: A student adds a piece of zinc to a test tube containing propanoic acid. Explain what the student would observe and write a balanced chemical equation for the reaction.
· Observation: Bubbles of gas (hydrogen) are produced, but the reaction is slower than the reaction of zinc with a strong acid like hydrochloric acid.
· Balanced equation:
2CH_3CH_2COOH + Zn \rightarrow (CH_3CH_2COO)_2Zn + H_2
Short Answer: In the preparation of an ester, concentrated sulfuric acid is used. Explain two roles of the concentrated sulfuric acid in this reaction.
Catalyst: Speeds up the reaction without being used up. (1 mark)
2. Dehydrating agent: Removes water (a product) to help drive the equilibrium towards the ester.
Multiple Choice: Which of the following is a disadvantage of disposing of waste polymers (plastics) by incineration?
A) It uses large areas of land.
B) The waste remains for thousands of years.
C) It releases toxic and greenhouse gases.
D) It is a cheap method.
C) It releases toxic and greenhouse gases.
Multiple Choice: A polymer is made from the monomer tetrafluoroethene. What is the name of this polymer and its main property?
A) Poly(chloroethene); strong and rigid
B) Poly(tetrafluoroethene); provides a non-stick surface
C) Poly(ethene); very flexible
D) Poly(propene); slightly strong
B) Poly(tetrafluoroethene); provides a non-stick surface
Multiple Choice: A diol (an alcohol with two -OH groups) reacts with a dioic acid (a carboxylic acid with two -COOH groups). What type of polymer is formed and what is the name of the bond that links the monomers?
A) Addition polymer; C-C bond
B) Polyester; -COO- bond
C) Poly(alkene); double bond
D) Polyamide; -CONH- bond
B) Polyester; -COO- bond
Short Answer: The diagram shows two monomers that can form a polyester.
Monomer A: HOOC-CH₂-COOH (Propanedioic acid)
Monomer B: HO-CH₂-CH₂-OH (Ethane-1,2-diol)
Draw a section of the polyester chain showing two repeat units. Identify the ester linkage in your drawing.
A correct section showing an alternating chain of the diacid and diol, with a -COO- linkage between them. The drawing should clearly show the bond between the carbon of the acid and the oxygen of the alcohol.
Short Answer: Explain why condensation polymerization is different from addition polymerization. Refer to the types of monomers, the functional groups involved, and any small molecules formed. Use polyesters as an example.
ddition polymers form from one type of alkene monomer with a C=C double bond. No small molecule is lost. (1 mark) Condensation polymers form from two different monomers (e.g., a diol and a dioic acid) with functional groups at each end. (1 mark) A small molecule, such as water, is lost during each bond formation. (1 mark) Polyesters are formed when a diol and a dioic acid react, losing water and creating a -COO- (ester) bond. (1 mark)
Multiple Choice: A student suggests that all alkanes are saturated hydrocarbons. Which statement best explains why this is correct?
A) They contain only single bonds between carbon atoms.
B) They contain a double bond between carbon atoms.
C) They contain a triple bond between carbon atoms.
D) They have the functional group -OH.
A) They contain only single bonds between carbon atoms.
Multiple Choice: A polymer is made from a monomer with the formula CH₂=CCl₂. Which diagram correctly shows a section of this polymer?
A)[-CH2-CCl2]n
B) [-CHCl-CHCl-]n
C) [-CH2-CHCl-]n
D) [-CCl2-CCl2-]n
A)[-CH2-CCl2]n
Multiple Choice: In the fermentation of glucose to produce ethanol, the solution produced is only a dilute solution of ethanol (around 15%). Why is the concentration of ethanol limited?
A) Yeast dies when the concentration of alcohol exceeds a certain level.
B) The reaction is reversible and reaches equilibrium.
C) The sugar is used up too quickly.
D) The temperature is too high, causing the ethanol to evaporate.
A) Yeast dies when the concentration of alcohol exceeds a certain level.
Short Answer: Compare and contrast the two methods for producing ethanol: fermentation of glucose and hydration of ethene. In your answer, discuss the raw materials, conditions, type of process (renewable/non-renewable), and the purity of the product.
Feature Fermentation Hydration
Raw Materials Renewable (sugar cane, grains) Non-renewable (crude oil → ethene)
Conditions Anaerobic, 30°C, yeast catalyst 300°C, 60-70 atm, phosphoric acid catalyst
Process Type Batch process, slow Continuous process, fast
Product Purity Impure, dilute (approx. 15%) Pure, concentrated
Short Answer: A student wants to synthesize propyl ethanoate. Identify the two starting materials needed. Describe the experimental procedure to prepare and purify a sample of this ester. Include the role of each chemical used and a key safety precaution.
Starting materials: Propanoic acid and ethanol.
1. Mix the carboxylic acid and alcohol in a flask with a few drops of concentrated sulfuric acid. (1 mark)
2. Heat the mixture under reflux to prevent the loss of volatile reactants. (1 mark)
3. After heating, pour the mixture into a beaker of sodium carbonate solution to neutralize the acid catalyst. (1 mark)
4. The ester will form a separate layer. Use a separating funnel to separate the ester layer. (1 mark)
Role: Conc. H_2SO_4 acts as a catalyst and dehydrating agent.
Safety: Wear gloves and safety goggles; the chemicals are flammable and corrosive.