Acids & Bases Flashcards

1
Q

What is an acid?

A

An acid is a substance that produces H+ ions in an aqueous solution.

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2
Q

What are the properties of an acid?

A
  1. Acids have a sour taste.
  2. Acids dissolve in water to form solutions which conduct electricity.
  3. Acids turn moist blue litmus paper red.
  4. Acids react with reactive metal to form salt and hydrogen gas.
  5. Acids eact with carbonates to form salt, water and carbon dioxide.
  6. Acids react with metal oxides and hydroxides to form salt and water only. (Neutralisation reaction)
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3
Q

What is the general chemical equation of reacting acid with a reactive metal?

A

Acid + metal —> Salt + H2 (g)

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4
Q

What is the general chemical equation for reacting acid with a carbonate?

A

Acid + carbonate —> salt + CO2 (g) + H2O (l)

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5
Q

What is the general chemical equation for reacting acid with metal oxide/hydroxide?

A

acid + metal oxide/hydroxide —> salt + H2O (l)

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6
Q

Explain the reaction between lead and dilute hydrochloric acid.

A

Lead appears to not react with dilute hydrochloric acid. This initial reaction produces a layer of lead (ii) chloride, which is insoluble in water. This layer forms a layer that coats around the original metal, thus preventing any furhter reaction with the acid.

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7
Q

What is a base?

A

A base is any metal oxide or hydroxide that reacts with an acid to produce a salt and water only. (Basically a base can be a metal oxide/hydroxide)

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8
Q

What is an alkali?

A

An alkali is a substance that produces OH- ions, in an aqueous solution. It is a special class of base that is soluble in water. (Basically metal hydroxides)

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9
Q

What is the general chemical equation for the reaction between an acid and a base?

A

Acid + Base —> Salt + H2O (l)

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10
Q

What is the general chemical equation for the reaction between an acid and an alkali?

A

acid + alkali —> salt + H2O (l)

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10
Q

How do you tell if the reaction is a neutralisation reaction?

A

It is only a neutralisation reaction when the reaction between an acid and alkali produces salt and water only.

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11
Q

What is the general chemical equation for the reaction between alkali and ammonia salts?

A

Alkali + Ammonia salt —> Salt + H2O (l) + NH3 (g)

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12
Q

What is the general chemical equation for the reaction between an alkali and metal salts?

A

Alkali (with metal A) + salt (with metal B) —> Salt (with metal A) + Metal hydroxide (with metal B)

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13
Q

What is a strong acid?

A

A strong acid completely ionises in an aqueous solution.

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14
Q

What is a weak acid?

A

A weak acid is only partially ionised in an aqueous solution.

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15
Q

Give 1 example of strong and weak acids each.

A

Strong: hydrochloric acid (HCl)
Weak: ethanoic acid (CH3COOH)

16
Q

Is the strength of an acid the same as the concentration of an acid?

A

No, it is not the same. The strength of the acid refers to how easily an acid ionises when dissolved in water. The concentration of an acid refers to how many molecules of the acid is dissolved in one volume unit of solution.

17
Q

How do you read a pH scale?

A

Below 7 is acidic, above 7 is alkaline, and 7 is neutral.

18
Q

What are some commonly used pH indicators?

A

Universal Indicator, phenolphthalein, methyl orange, bromothymol blue.

19
Q

What is the pH range where phenolphthalein changes colour?

A

8 to 10

20
Q

What is the pH range where methyl orange changes colour?

A

3 to 4.5

21
Q

What is the pH range where bromothymol blue changes colour?

A

6 to 7.5

22
Q

How many types of oxides are there? What are they?

A
  1. Acidic, basic, neutral and amphoteric oxides.
23
Q

What does acidic oxides react with?

A

Bases/alkalis.

24
Q

What does basic oxides react with?

A

Acids.

25
Q

What does neutral oxides react with?

A

nothing.

26
Q

What does amphoteric oxides react with?

A

Both acids and bases/alkalis.

27
Q

Give 2 examples of acidic oxides.

A

Carbon dioxide, sulfur trioxide.

28
Q

Give 2 examples of basic oxides.

A

Calcium oxide, potassium oxide.

29
Q

Give 2 examples of neutral oxides.

A

Water (H2O), carbon monoxide.

30
Q

Give 2 examples of amphoteric oxides.

A

Lead (II) oxide, aluminium oxide.