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Chemistry Flashcards

1
Q

What is a homologous series?

A

A homologous series is a group of organic compunds which share the same functional group and can be written with the same general formula .

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2
Q

Why does magnesium displace copper in copper (II) sulfate solution?

A

Magnesium is above copper in the electrochemical series of metals. Hence, it is the stronger reducing agent agents, readily donating electrons to copper cations, discharging them, forming magnesium cations and neutral copper atoms. Thus, copper is displaced forming magnesium sulfate solution.

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3
Q

What 3 factors affect the preferential discharge of an anion during electrolysis? Briefly explain why each factor has its effect.

A

Recall: Positive Consciousness Activist (Position, Concentration, Anode used)

  1. The type of anode (An active anode can take part in the electrolysis process. This usually involves the anode ionising instead of an anion being discharged.)
  2. The conc. of the electrolyte (A greater conc. of an ion makes it more like to be preferentially discharged. This rule mainly applies to solutions containing halide ions.)
  3. The position of the ion in the electrochemical series (The lower the ion is in the electrochemical series of anions, the more likely it is to be preferentially discharged. This is because ons at the top the series are more stable and ions at the bottom are less stable)
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4
Q

What is the Faraday constant?

A

The Faraday constant is the size of the electrical charge on one mole of electrons, i.e. 96500 C/mol.

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5
Q

Define electrolysis.

A

Electrolysis is the chemical change occurring when an electric current passes through an electrolyte.

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6
Q

What is an electrolyte?

A

An electrolyte is a molten ionic compound or an aqueous solution of an ionic compound which contains mobile electrons.

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7
Q

What are the three components of an electrolytic cell?

A

Recall BEE: Battery (or other DC power supply, Electrolyte, Electrodes.

  1. The electrolyte
  2. A battery or other DC power supply
  3. The electrodes
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8
Q

What is a conductor and what is a non-conductor?

A

A conductor is a material which allows an electric current to pass through it.

A non-conductor is a material which does not allow an electric current to pass through it.

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9
Q

Why is pure water considered an extremely weak electrolyte?

A

Approximately one in every 5.56 x 10^8 water molecules ionise at any one time. This means that is has a very lower conc. of ions.

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10
Q

What is the electrochemical series of metals? What increases going up the series?

A

The electrochemical series of metals places metals in order of how easily they ionise and it can be used to predict certain chemical reactions. Strength as a reducing agent increases going up the series (selfless metal atoms, they give away electrons).

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11
Q

What is the electrochemical series of non-metals? What increases going up the series?

A

The electrochemical series of non-metals places non-metals in order of how easily they ionise and can be used to predict certain chemical reactions. Strength as an oxidising agent increases going up the series (selfish, they steal electrons from others).

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12
Q

How does the electrochemical series of metals differ from the reactivity series of metals?

A

CALCIUM AND SODIUM ARE SWAPPED. Mercury is excluded. Gold is left out.

Reactivity Series: Pretty Sally Clean Married A Zulu In Lonely Hawaii Copper Mercury Silver Gold (Potassium, Sodium, Calcium, Magnesium, Aluminium, Zinc, Iron, Lead, Hydrogen, Copper, Mercury, Silver, Gold)

Electrochemical Series: Potassium, Calcium, Sodium, Magnesium, Aluminium, Zinc, Iron, Lead, Hydrogen, Copper, Silver

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13
Q

What are 4 characteristics of a homologous series besides the ones in the definition?

A
  1. The molecular formula of each memebre of a series differs from the memeber directly before it or after it by CH2, or a relative molecular mass of 14.
  2. Members of a series can all be prepared using the same general method.
  3. Members of a series all possess similar chemical properties. However, as the molar mass (no. of C atoms per molecule) incease reactivity decreases.
  4. Members of a series show a gradual change in their physical properties as the number of C atoms per molecule increases. Generally, as molar mass increases, the melting poing, boiling point and density increase.
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14
Q

Define cracking.

A

Cracking is the process by which long chain hydrocarbon molecules are broken down into shorter chain hydrocarbon molecules by breaking carbon-carbon bonds.

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15
Q

What is a hydrocarbon?

A

A hydrocarbon is an organic compound composed of carbon and hydrogen atoms only.

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16
Q

Write the general equation for the combustion of an alkane.

A

[See textbook.]

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17
Q

What are the four reasons why alkanes are used as fuels?

A
  1. They burn very easily.
  2. They release large amounts of energy when they burn because the reactions are exothermic.
  3. They burn with clean, blue flames which contain very little soot.
  4. They are easy to store, transport and distribute.
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18
Q

Why alkanes used as solvents? Give two examples of alkanes being used as solvents.

A

Alkanes are used as solvents because they are NON-POLAR and are able to dissolve other non-polar solutes, e.g. hexane and heptane are used as solvents for making fast drying glues and extracting oils from seeds.

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19
Q

What is biogas and how is it made? What is its percentage composition and other trace gases?

A

Biogas is a renewable energy source. It is produced by naturally occuring anaerobic bacteria breaking down organic matter such as manure in the absence of oxygen in an ANAEROBIC DIGESTER. The biogas produced is a mixture of approx. 60% methane, 40% carbon diozide and traces of other gases such as hydrogen sulfide.

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20
Q

What are 4 uses of biogas?

A

Biogas can be used directly as fuel for cooking, heating and to generate electricity, or it can be upgraded to almost pure methane, known as biomethane, by the removal or the other gases (carbon dioxide and trace amounts of other gases).

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21
Q

Define structural isomerism.

A

Structural isomerism is the occurence of two or more organic compounds which have the same molecular formula but different structural formulae.

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22
Q

State the 2 ways in which metallic and electrolytic conduction differ.

A
  1. Means of carrying current: In a metal, mobile electrons carry the electic current. In an electrolyte, mobile ions no longer held together by ionic bond carry the electric current.
  2. Chemical composition after the electric current flows through the substance: A metal remains chemically unchanged. An electrolyte decomposes.
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23
Q

What is the electrochemical series of anions from highest to lowest?

A

RECALL: Four Super Ninja Cool Bears Investigate Orwell

Fluorine, Sulphate ion, Nitrate ion, Chlorine, Bromine, Iodine, Hydroxide ion

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24
Q

What are the TWO uses of alkenes?

A
  1. Alkenes are used as STARTING MATERIALS in the manufacture of many chemicals such as alcohols, antifreezes, synthetic rubbers and haloalkanes.
  2. Alkenes are used to manufacture a wide range of plastics.
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25
Q

What are TWO uses of alkanes?

A
  1. Alkanes are used as fuels
  2. Alkanes are used as solvents
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26
Q

Why are alcohols polar? Subsequently, why are alcohols less volatile than their corresponding alkanes?

A

The possess the polar hydroxyl group -OH. Because of the polar -OH groups, forces of attraction between alcohol molecules are stronger than the forces of attraction between non-polar alkanes molecules with the same number of carbon atoms.

NOTE: All alcohols are liquids or solids as room temperature.

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27
Q

What happens to the strength of reactions alcohols undergo as the number of carbon atoms per molecule (molar mass) increases? Why are alcohols soluble in water. What happens to the solubility of alcohols as the number of carbon atoms per molecule (molar mass) increases?

A

The strength of reactions decreases as the number of carbon atoms per molecule increases. Alcohols are soluble in water because they are polar and water is a polar solvent. Solubility of alcohols decreases as the numebr of carbon atoms per molecule increases.

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28
Q

Write the general formulae for alkanes, alkenes, alkanoic acids, ester and alcohols.

A

[See notes.]

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29
Q

Write the equation for the combustion of ethanol in oxygen. What type of flame does ethanol burn with and why?

A

[See pg. 141 of Textbook for the equation.]

Ethanol burns with a clear, blue, non-smoky flames due to the low ration of carbon to hydrogen atoms in the molecules (Just like in alkanes).

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30
Q

Write the equation for ethanol reacting with sodium.

A

[See pg. 141 of Textbook.]

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31
Q

What are the two ways ethanol can be dehydrated to ethene? Write the equation for one.

A
  1. Heating ethanol at a temperature of about 170 degrees Celsisus with excress conc. sulfuric acid. (equation on pg. 141 of Textbook)
  2. Passing ethanol vapour over heated aluminium oxide.
32
Q

Write the equation for the oxidation of ethanol to ethanoic acid. What two oxidising agents can be used?

A

[See pg. 142 of textbook for equation.]

  1. Acidified potassium manganate (VII) solution
  2. Acidified potassium dichromate (VI) solution
33
Q

What are the principles behind a breathlyser test?

A

Orange acidified potassium dichromate (VI) crystals can be used in the breathalyser test to determine the alcohol content of a driver’s breath. The driver blows over the crystals and if ethanol vapour is present, it reduces the orange dichromate (VI) ion to the green chromium (III) ion. This turns the crystals green.

34
Q

How is ethanol produced by the fermentation of carbohydrates? Include a balanced chemical equation in your answer.

A

Yeast ferments carbohydrates UNDER ANAEROBIC CONDITIONS. Yeast produces enzymes that break down complex carbohydrates into simple sugars, mainly glucose. It then produces the enzyme zymase which changes the simple sugars into ethanol and carbon dioxide.

[See equation on pg. 142 of Textbook.]

35
Q

When does fermentation stop. Why? How is ethanol extracted from the fermentation mixture?

A

Fermentation stops when the concentration of ethanol in the fermentation mixture is about 14%. At this concentration, ethanol begins to denature zymase. Ethanol which is about 96% pure is then obtained fromt the mixture using fractional distillation, collecting the fraction that distils at 78 degrees Celsius (boiling point of ethanol).

36
Q

Where is wine made and how? Why should air not come into contact with wine (state the balanced chemical equation for why)?

A

Wine is made from grapes in a winery. Yeast is added to crushed grapes and it ferments the sugars present. Air should not come into contact with the wine because certain aerobic bacteria oxidise the ethanol (remember, ethanol acts as a REDUCING AGENT) to ethanoic acid, causing the wine to sour.

[See equation on pg. 142 of Textbook.]

37
Q

How is rum made and stored?

A

Rum is made from molasses in a rum distillery. Yeast is added to the molasses and it ferments the sugars present. The mixture is then fractionally distilled. The distillate is diluted with water and transferred to oak barrels to be aged.

38
Q

Why are alkanoic/ carboxylic acids polar? Subsequently, why are they less volatile than their corresponding alkanes? Why are they considered weak acids?

A

Carboxylic acids are polar due to the -OH part of the carboxyl group -COOH being polar. Like alcohols, they are less volatile than their corresponding alkanes because the polar -OH groups in their molecules mean that the forces of attraction between alkanoic acid molecule are stronger than the forces between non-polar alkane molecules. They are considered weak acids because they only partially ionise in water.

39
Q

What is the equation for when a carboxylic acid reacts with a metal oxide/hydroxide in word form? Subsequently, write the balanced chemical equation for aqueous ethanoic acid reacting with potassium hydroxide solution.

A

metal oxide/hydroxide + carboxylic acid —-> salt + water

[See equation on pg. 143 of textbook.]

40
Q

What happens when an anhydrous alkanoic acid reacts with an alcohol. What is the name of this reaction?

A

An ester and water are produced. This reaction is called ESTERIFICATION.

41
Q

Define acidic, basic, amphoteric, and neutral oxides and give examples of each.

A

[See pg. 70 of textbook]

42
Q

Explain why an acid can be defined as a proton donor.

A

In aqueous solutions, H+ ions present in acids are single protons. Each H+ ion is a hydrogen nucleus containing a single proton formed by a hydrogen atom, 11H. Losing its valence electron. When an acid reacts, it can give away or donate its H+ ions or protons to the other reactant. Hence, an acid can be called a proton donor.

43
Q

What is a salt?

A

A compound formed when some or all of the hydrogen ions in an acid are replaced by metal or ammonium ions.

44
Q

What salts can be prepared using ionic precipitation? What reactants must be used and why? What is the five-step method used in ionic precipitation? Show a balanced chemical equation and an ionic equation for lead (II) sulphate being prepared by this method.

A

RECALL: Dissolve, Mix, Filter, Wash, Dry

Dissolve each salt in distilled water to make two solutions. Mix the solutions to form a precipitate. Filter to separate the precipitate from the mixture. Wash the precipitate (residue) with distilled water. Dry the residue.

[See textbook pg. 73]

45
Q

What salts can be prepared via a titration? What reactants must be used and why? What is the three-step method to perform a titration? Use potassium sulphate and potassium hydrogen sulphate as two examples showing balanced chemical equations.

A

[See textbook pg. 73]

46
Q

State the chemical formula for sodium hydrogen carbonate. State its use and explain it. add an ionic equation to support your answer.

A

[See textbook pg. 76.]

47
Q

State the chemical formula for sodium benzoate. State its use. Explain.

A

Used to preserve foods with low pH such as fruit juices and fizzy drinks. At a low pH, it is converted to benzoic acid which prevents the growth of microorganisms.

[See textbook pg. 76.]

48
Q

Sodium chloride is used to preserve food such as meat and fish. How is this done?

A

Sodium chloride draws water out of the cells of food via osmosis, preventing decay as there’s no water available in cells for the chemical reactions which cause decay. Furthermore, sodium chloride draws water out of microorganisms via osmosis, inhibiting their growth and further contributing to the preservation of food.

49
Q

State the chemical formula for calcium carbonate and its other name. State its use. Explain using an ionic equation to support your answer.

A

[See textbook pg. 76.]

50
Q

State the chemical formula for gypsum. State its use. Explain.

A

Used to manufacture plaster of Paris used as a building material and for setting broken bones. Plaster of Paris is made of anhydrous calcium sulfate. When water is added, heat is given off and a paste forms. The paste is used to coat walls and ceilings, and bandages impregnated in it are used to make orthopedic casts.

51
Q

State the chemical formula for Epsom salt. State its two uses. Explain both.

A

Epsom salt,, has numerous health benefits. Added to bath water, it relieves stress, aches, pains, and reduces inflammation. Taken orally, it works as a laxative. It also improves plant growth.

[See textbook pg. 76.]

52
Q

What are the dangers of sodium benzoate, sodium chloride, sodium nitrate, and sodium nitrite?

A

Sodium benzoate may be carcinogenic and may increase hyperactivity and asthma in children.

Sodium chloride can lead to hypertension (high blood pressure) if consumed in excess. Sodium nitrate and nitrites may be carcinogenic and may cause brain damage in infants.

53
Q

What is an amphoteric oxide or hydroxide. Write the formulae for the ions formed when the “ZAP” hydroxides and oxides react with a strong alkali.

A

An amphoteric oxide or hydroxide is one that can react with both acids and strong alkalis to form a salt and water.

[See textbook pg. 69 for formulae]

54
Q

What salts are prepared by direct combination? What reactants must be used and why? What is the method used? Write a balanced chemical equation for the preparation of aluminum chloride to support your answer.

A

[See textbook pg. 74.]

55
Q

What salts are prepared by a reactive metal reacting with an acid? What are the reactants used and why? What is the four-step process for this method of salt preparation? Write a balanced chemical equation for the preparation of zinc chloride to support this answer.

A

[See textbook pg. 74.]

56
Q

What salts are prepared by an insoluble base reacting with an acid? What reactants are used and why? What is the four-step process to perform this method of salt preparation? Rights to balanced chemical equations for the preparation of magnesium sulfate who support your answer.

A

[See textbook pg. 74.]

57
Q

What salts are prepared from an insoluble carbonate reacting with an acid? What reactants are used and why? What is the four-step method used in this method of salt preparation? Use copper (II) nitrate as an example adding a balanced chemical equation to support your answer.

A

[See textbook pg. 75.]

58
Q

Construct a flow diagram summarizing the methods of salt preparation.

A

[See textbook pg. 75.]

59
Q

What is an acid salt and a normal salt?

A

An acid salt is a compound formed when the hydrogen ions in an acid are only partially replaced by metal or ammonium ions.

A normal salt is a compound formed when all of the hydrogen ions in an acid are replaced by metal or ammonium ions.

60
Q

Define water of crystallisation. Write the equation for hydrated copper (II) sulphate become anhydrous copper (II) sulphate, stating the colours.

A

Water of crystallisation is a fixed proportion of water molecules held within the crystal lattice of a salt.

[See pg. 72]

61
Q

What three factors must be considered when preparing any salt?

A

The solubility of the salt being prepared.

The solubility of the reactants being used to prepare the salt.

The hydration of the salt being prepared.

62
Q

What are five properties of aqueous acids?

A

They have a sour taste.

They are corrosive.

They change blue litmus to red.

They have a pH value of less than 7.

They conduct an electric current, that is, they are electrolytes.

63
Q

Define basicity of acids.

A

Basicity is the number of hydrogen ions produced per molecule of acid when the acid dissolves in water.

64
Q

Define the term acid anhydride. State the equations for 4 examples, adding names, when reacting with water.

A

RECALL: Clever (Carbon dioxide), Scientists (Sulphur dioxide), Say (Sulphur trioxide), Nitrogen (Nitrogen dioxide).

An acid anhydride is a compound that reacts with water to form an acid.

[See pg. 66 for equations]

65
Q

What is a base? What compounds are bases. Explain why a base is defined this way.

A

A base is a proton acceptor. Bases include metal oxides, metal hydroxides and ammonia when a base reacts with an acid the oxide ions or hydroxide ions in the base except the hydrogen ions or single protons from the acid forming water.

66
Q

What is an alkali? Write the equation for ammonia gas ionising in water.

A

An alkali is a base which dissolves in water to form a solution that contains hydroxide ions.

[See pg. 67 for equation]

67
Q

What are six properties of aqueous alkalis?

A

They have a bitter taste.

They are corrosive.

They feel soapy.

They have a pH value greater than 7.

They conduct an electric current, so they are electrolytes.

68
Q

Write in the words the reaction between a base and an ammonium salt. Write the balanced chemical equation for the reaction between magnesium hydroxide and ammonium chloride.

A

Base + Ammonium Salt —> Salt + Ammonia + Water

[See pg. 68]

69
Q

Construct a table showing the colour of litmus, methyl orange, screened methyl orange and phenolphthalein in acidic and alkaline solutions respectively.

A

[See pg. 68]

70
Q

State the solubility rules for ionic compounds.

A

[See pg. 46]

71
Q

Write in words the equation for esterification including the reaction conditions. include the balanced chemical equation for ethanoic acid and propanol undergoing esterification. What are the two functions of a certain reaction condition? State two ways of representing the ester functional group.

A

[See pg 143 and 144]

72
Q

Chemically, what are animal fats and vegetable oils, and what are they formed from?

A

They are ester formed from fatty acids (long chain alkanoic acids) and glycerol (an alkanol)

73
Q

Explain saponification. write the balanced equation for and explain the production of sodium octadecanoate, adding words.

A

Large ester molecules found in animal fats and vegetable oils undergo alkaline hydrolysis by being boiled with concentrated potassium or sodium hydroxide solution. The reaction produces soap, which is the potassium or sodium salt of a long chain carboxylic acid (fatty acid) and glycerol.

The fat glyceryl octadecanoate is an ester of octadecanoic acid and glycerol. Saponification of glyceryl octadecanoate by boiling with sodium hydroxide solution forms sodium octadecanoate and glycerol. Sodium octadecanoate, also called sodium stearate, is the most common form of soap.

[See pg. 145 for equation]

74
Q

Define hydrolysis. explain what happens in acid and alkaline hydrolysis of esters stating the balanced chemical equations for propyl ethanoate undergoing both.

A

Hydrolysis is the process of breaking down molecules of a compound into smaller molecules by reacting the compound with water.

ACID HYDROLYSIS: The ester is heated with dilute hydrochloric acid or sulfuric acid. The acid acts as a catalyst. The products of the hydrolysis are the carboxylic acid and the alcohol from which the ester was formed.

ALKALINE HYDROLYSIS: The ester is heated with potassium or sodium hydroxide solution. The products are the potassium or sodium salt of the alkanoic acid and the alcohol from which the ester was formed.

[See equations of page 145]

75
Q

Define Green Chemistry. What are six principles of Green Chemistry (Mnemonic)? What are four benefits of Green Chemistry?

A

Green Chemistry is the utilisation of a set of principles in the design, manufacture and application of chemical products that reduces or eliminates the use and generation of hazardous substances

Mnemonic: Ducks And Cows Find Dry Water

  1. Design for degradation
  2. Maximise (a)tom economy
  3. Use (c)atalysts instead of stoichiometric reagents
  4. Use renewable (f)eedstocks
  5. Reduce (d)erivitisation
  6. Prevent (w)aste

Four benefits:

  1. Reduced wastage
  2. Reduced energy usage
  3. Reduced pollution
  4. Increased competitiveness of chemical manufacturers

CSEC Flashcards (7 decks)

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