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Chemistry Module 2 - Own Flashcards > Chapter 4 - Acids and Redox > Flashcards

Chapter 4 - Acids and Redox Flashcards

1
Q

What is an acid?

A

An acid is a substance that releases H+ ions (protons) when dissolved in water.
–> Proton donor

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2
Q

What is the general acid reaction?

A

Acid(H-containing compound) + Water –> H+(aq) + Anion(aq)

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3
Q

What are the 4 most common acids?

A
  1. Hydrochloric Acid
  2. Sulfuric Acid
  3. Nitric Acid
  4. Ethanoic Acid (Vinegar)
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4
Q

What is the formula of Hydrochloric Acid?

A

HCl

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5
Q

What is the formula for Sulfuric Acid?

A

H2SO4

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6
Q

What is the formula for Nitric Acid?

A

HNO3

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7
Q

What is the formula for Ethanoic Acid (Vinegar)?

A

CH3COOH

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8
Q

What are the common uses of Hydrochloric Acid?

A

Found in stomach acid (digestive aid)

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9
Q

What are the common uses of Sulfuric Acid?

A

Car batteries, industrial chemicals

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10
Q

What are the common uses of Nitric Acid?

A

Fertilisers, Explosives

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11
Q

What are the common uses of Ethanoic Acid (Vinegar)?

A

Food preservation, Cleaning Agent

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12
Q

What is the difference between a strong and weak acid?

A

A strong acid is an acid that completely dissociates in water, releasing all available H+ ions.

A weak acid is an acid that only partially dissociate in water, so doesn’t release all its H+ ions.

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13
Q

What is the dissociation like in a strong and weak acid?

A

Strong –> Complete dissociation

Weak –> Partial dissociation

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14
Q

What is the electrical conductivity like in a strong and weak acid?

A

Strong –> High (more H+)

Weak –> Low (fewer H+)

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15
Q

What is a base?

A

A base neutralizes an acid to form a salt.

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16
Q

What type of substances act as bases?

A
  1. metal oxides
  2. metal hydroxides
  3. metal carbonates
  4. ammonia
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17
Q

Give examples of Metal Oxides that act as bases.

A

CuO,MgO,CaO

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18
Q

Give examples of Metal Hydroxides that act as bases.

A

NaOH,KOH

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19
Q

Give examples of Metal Carbonates that act as bases.

A

CaCO3, Na2CO3

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20
Q

What is an alkali?

A

An alkali is a base that dissolves in water to release hydroxide ions (OH-).

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21
Q

What happens during neutralization?

A

H+ ions from the acid react with the base to form a salt and water.

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22
Q

What is the general equation of a neutralisation reaction?

A

Acid + Base –> Base + Water

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23
Q

What is an amphoteric substance?

A

A substance that acts as both an acid and base.

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24
Q

What are the products when an acid reacts with a metal?

A

Metal + Acid –> Salt + Hydrogen

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25
Q

What are the products when an acid reacts with a metal oxide?

A

Metal Oxide + Acid –> Salt + Water

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26
Q

What are the products when an acid reacts with an alkali?

A

Acid + Alkali –> Salt + Water

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27
Q

What are the products when an acid reacts with a carbonate?

A

HINT: CASHOCO
Carbonate + Acid –> Salt + Carbon Dioxide + Water

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28
Q

What are the products when an acid reacts with a base?

A

HINT: BASHO
Base + Acid –> Salt + Water

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29
Q

How is a salt formed?

A

A salt is a compound formed when the H+ of an ion is replaced by a metal ion or positive ion.

30
Q

What type of salt is formed from common acid Hydrochloric Acid?

A

Salt type –> Chloride

31
Q

What type of salt is formed from common acid Sulfuric Acid?

A

Salt type –> Sulfate

32
Q

What type of salt is formed from common acid Nitric Acid?

A

Salt type –> Nitrate

33
Q

What type of salt is formed from common acid Ethanoic Acid?

A

Salt type –> Ethanoate

34
Q

How does sulfuric acid (H2SO4) dissociate in water?

A
  1. Initially, H2SO4 dissociates completely to release one H+:
    H2SO4 –> H+ (aq) + HSO4(-)(aq)
  2. The HSO4- ions partially dissociate:
    HSO4-(aq) ⇌ H+ (aq) + SO4(2-)(aq)
35
Q

Why is H2SO4 considered a strong acid for its first hydrogen?

A

The first dissociation is complete, making it behave as a strong acid.

36
Q

What is a titration, and what is used for?

A

A titration is a technique used to accurately measure the volume of one solution that reacts exactly with another. It is used for:
1. Finding the concentration of a solution.
2. Identifying unknown chemicals.
3. Checking the purity of a substance.

37
Q

Why is purity important in titrations?

A

Purity is essential, especially for compounds used in medicines, food, and cosmetics, as even a small impurity can cause significant harm, particularly in pharmaceuticals.

38
Q

What is a standard solution?

A

A standard solution is a solution of known concentration.

39
Q

What equipment is used to prepare a standard solution, and what are their tolerances?

A

A volumetric flask is used to make a standard solution with these typical tolerances:
* 100 cm³ flask: ±0.20 cm³
* 250 cm³ flask: ±0.30 cm³

40
Q

How do you prepare a standard solution?

A
  1. Accurately weigh the solid.
  2. Dissolve the solid in a beaker with less distilled water than needed to fill the volumetric flask.
  3. Transfer the solution to a volumetric flask and rinse the beaker with distilled water.
  4. Carefully add distilled water drop by drop until the bottom of the meniscus aligns with the graduation mark.
  5. Invert the flask several times to thoroughly mix the solution.
41
Q

Why is it important to mix the solution thoroughly when preparing a standard solution?

A

If the solution is not mixed thoroughly, titration results may be inconsistent.

42
Q

What apparatus is used in an acid-base titration, and what are their uncertainties?

A
  1. Pipettes:
    * 10 cm³ pipette: ±0.04 cm³
    * 25 cm³ pipette: ±0.06 cm³
  2. Burette:
    * 50 cm³ burette: ±0.10 cm³
43
Q

How should burette readings be recorded?

A

Record burette readings to the nearest ±0.05 cm³ with two decimal places, where the last digit is either 0 or 5.

44
Q

What is the procedure for performing an acid-base titration?

A
  1. Use a pipette to add a measured volume of one solution to a conical flask.
  2. Fill a burette with the other solution and record its initial reading.
  3. Add a few drops of an indicator to the conical flask.
  4. Run the solution from the burette into the conical flask, swirling to mix.
  5. Record the final burette reading.
  6. Calculate the titre by subtracting the initial reading from the final reading.
  7. Perform a trial titration to find the approximate titre.
  8. Repeat the titration accurately, adding dropwise near the endpoint, until two concordant titres (within ±0.10 cm³) are obtained.
45
Q

How do you calculate the mean titre?

A

Include only the concordant titres (within ±0.10 cm³) in the calculation. Disregard outliers to maintain accuracy.

46
Q

What are the steps for analyzing titration results?

A
  1. Calculate the moles of solute in the solution for which both concentration and volume are known.
  2. Use the balanced chemical equation to find the moles of solute in the other solution.
  3. Determine the unknown information about the solute (e.g., concentration or volume).
47
Q

What is the colour of methyl orange in an acid, base and at end point?

A

Acid = Red
Base = Yellow
End Point = Orange

48
Q

What is an oxidation number, and why is it useful?

A

An oxidation number is a value based on a set of rules that represents the number of electrons involved in bonding to a different element. It is useful for writing formulas and balancing equations, ensuring all electrons are accounted for.

49
Q

What is the oxidation number for an element in its pure form?

A

The oxidation number of an element in its pure form is always 0.
Examples: H₂, O₂, P₄, S₈, Na, and Fe.

50
Q

What are the oxidation numbers of O in compounds?

A

O (Oxygen) –> -2

51
Q

What are the oxidation numbers of H in compounds?

A

H (Hydrogen) –> +1

52
Q

What are the oxidation numbers of F in compounds?

A

F (Fluorine) –> -1

53
Q

What are the oxidation numbers of Na+ and K+ in compounds?

A

Na+, K+ –> +1

54
Q

What are the oxidation numbers of Mg²⁺, Ca²⁺ in compounds?

A

Mg²⁺, Ca²⁺ –> +2

55
Q

What are the oxidation numbers of Cl⁻, Br⁻, I⁻ in compounds?

A

Cl⁻, Br⁻, I⁻ –> -1

56
Q

What are the oxidation numbers of H in metal hydrides (e.g., NaH) in compounds?

A

H in metal hydrides –> -1

57
Q

What are the oxidation numbers of O in peroxides (e.g., H₂O₂) in compounds?

A

O in peroxides –> -1

57
Q
A
58
Q

What are the oxidation numbers of O bonded to F (e.g., OF₂) in compounds?

A

O bonded to F –> +2

59
Q

What is the rule for the sum of oxidation numbers in compounds or ions?

A

The sum of the oxidation numbers is equal to the total charge of the compound or ion.

60
Q

How are Roman numerals used in naming compounds? Give an example.

A

Roman numerals indicate the oxidation state of an element in a compound. For example:
* Iron(II): Fe²⁺ with oxidation number +2.
* Iron(III): Fe³⁺ with oxidation number +3.

61
Q

What is a redox reaction?

A

A redox reaction involves both reduction and oxidation. If one substance is reduced, another must be oxidized.

61
Q
A
62
Q

How were the terms oxidation and reduction originally defined?

A

Oxidation: Addition of oxygen.
Reduction: Removal of oxygen.

63
Q

How are oxidation and reduction defined in terms of electrons?

A

Reduction: Gain of electrons.
Oxidation: Loss of electrons.

64
Q

How do oxidation numbers change in redox reactions?

A

Reduction: A decrease in oxidation number.
Oxidation: An increase in oxidation number.
The total changes in oxidation number must balance for the reaction.

65
Q

What happens during the redox reactions of acids with metals?

A

Dilute acids react with some metals to produce a salt and hydrogen gas.

66
Q
A
67
Q

What is an oxyanions?

A

Negative ions that have an elements along with oxygen.

68
Q

What is a disproportionation reaction?

A

A disproportionation reaction is when an element is both reduced and oxidised in a chemical reduction.

Chemistry Module 2 - Own Flashcards (10 decks)

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