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Chemistry > Acids, Bases and Salts 1 > Flashcards

Acids, Bases and Salts 1 Flashcards

1
Q

State the formula for ethanoic acid.

A

CH3COOH

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2
Q

State the ions produced in aqueous solution of the following acids:
1: hydrochloric acid
2: nitric acid
3: sulfuric acid
4: ethanoic acid

A

1: H+ (aq), Cl- (aq)
2: H+ (aq), NO3 ^- (aq)
3: H+ (aq), SO4 ^2- (aq)
4: H+ (aq), CH3COOH ^- (aq)

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3
Q

Define an acid.

A

An acid is a substance in which its molecules dissociate in water to produce hydrogen ions.

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4
Q

What factor is responsible for the properties of acids?

A

The presence of hydrogen ions.

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5
Q

Ammonia and ethanol are hydrogen-containing compounds. Why are they not acids?

A

They do not produce hydrogen ions when dissolved in water.

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6
Q

Define the basicity of an acid.

A

The number of ionisable hydrogen ions that can be produced by a molecule of the acid.

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7
Q

State the number of hydrogen ions that can be yielded when
1: a molecule of a monobasic acid is dissociated.
2: a molecule of a dibasic acid is dissociated.
3: a molecule of a tribasic acid is dissociated.

A

1: 1 H+ ion
2: 2 H+ ions
3: 3 H+ ions

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8
Q

Define the strength of an acid.

A

The extent of an acid’s dissociation in water.

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9
Q

Define a strong acid and a weak acid respectively.

A

A strong acid is one in which its molecules dissociate completely in water to produce a high concentration of hydrogen ions.
A weak acid is one in which its molecules dissociate partially in water to produce a low concentration of hydrogen ions.

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10
Q

Name two types of uses for the following acids.
1: H2SO4
3: HCl
5: CH3CO2H
Name one type of use for the following acids.
4: HNO3
5: H3PO4
6: H2CO3

A

1: fertiliser / car batteries / detergents
2: cleaning of metals / leather processing
3: vinegar / glue
4: fertiliser / explosives
5: fertiliser / food additives
6: soft drinks

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11
Q

State the difference between a dilute acid solution and a concentrated acid solution.

A

A dilute acid solution contains a small amount of dissolved acid per unit volume of water, while a concentrated acid solution contains a large amount of dissolved acid per unit volume of water.

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12
Q

What does pH measure?

A

pH measures the concentration of H+ ions in an aqueous solution of an acid.

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13
Q

State the formula of pH.

A

pH = -lg [H+], where H+ refers to the concentration of H+ ions in water

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14
Q

State the factors affecting pH of an acid solution.

A

Its strength, concentration and basicity.

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15
Q

List all the properties of an acid.

A

1: It has a sour taste.
2: It dissolves in water to form solutions that conduct electricity.
3: It turns blue litmus paper red.
4: It reacts with reactive metals to form hydrogen gas and a salt.
5: It reacts with all carbonates to form carbon dioxide, water and a salt.
6: It reacts metal oxides and metal hydroxides to form salt and water.

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16
Q

Identify the unreactive metals.
calcium (Ca)
zinc (Zn)
copper (Cu)
tin (Sn)
silver (Ag)
gold (Au)
lead (Pb)
platinum (Pl)
aluminium (Al)
iron (Fe)

A

Cu, Ag, Au, Pl

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17
Q

Identify the metals that can be displaced from their oxide using carbon.
tin (Sn)
magnesium (Mg)
zinc (Zn)
gold (Au)
lead (Pb)
silver (Ag)
aluminium (Al)
copper (Cu)

A

Sn, Zn, Au, Pb, Ag, Cu

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18
Q

Complete the chemical reaction.
CuO (s) + H2 (g) -> ?

A

CuO (s) + H2 (g) -> Cu (s) + H2O (l)

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19
Q

Predict the observation when a magnesium ribbon is added to hydrochloric acid.

A

Brisk effervescence of colourless, odourless gas that extinguished a lighted splint is observed.

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20
Q

Define a salt.

A

A salt is the ionic compound formed when the hydrogen ions from an acid are displaced by metals or ammonium ions. The anion of salt comes from an acid.

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21
Q

Describe the test for hydrogen gas.

A

Place a lighted splint at the mouth of the reaction test tube. If the lighted splint extinguishes with a ‘pop’ sound, hydrogen gas is produced.

22
Q

Predict the observation when calcium carbonate is added to hydrochloric acid.

A

Brisk effervescence of colourless, odourless gas that produced a white precipitate when bubbled into limewater is observed.

23
Q

Describe the test for carbon dioxide gas.

A

Bubble the gas through a test tube of limewater using a delivery tube. If a white precipitate is formed with limewater, carbon dioxide gas is produced.

24
Q

Describe the neutralisation reaction.

A

Neutralisation is the combination of hydrogen ions from an acid with hydroxide ions from an alkali or base to form water molecules and salt as the only products.

25
Q

State the general ionic equation for neutralisation between acids and alkali.

A

H+ (aq) + OH- (aq) -> H2O (l)

26
Q

The following statements about sulfuric acid are all correct.
1: A white precipitate is formed when aqueous barium chloride is added.
2: The solution turns anhydrous copper(II) sulfate from white to blue.
3: Addition of Universal Indicator shows that the solution has a pH value of less than 7.0.
4: The solution reacts with copper(II) oxide, forming a blue solution.

Which two statements confirm the acidic nature of the solution?

A

3 and 4

27
Q

Define a base.

A

A base is a substance that dissociates in water to produce hydroxide ions.

28
Q

Define an alkali

A

A base that is soluble in water.

29
Q

State the ions produced in aqueous ammonia.

A

NH4 ^+ (aq) and OH- (aq)

30
Q

Define a strong base and a weak base respectively.

A

A strong base is one in which its molecules dissociates completely in water to produce a high concentration of hydroxide ions. A weak base is one in which its molecules dissociates partially in water to produce a low concentration of hydroxide ions.

31
Q

Define the acidity of a base.

A

The number of ionisable hydroxide ions that can be produced by a formula unit of the base.

32
Q

List all the properties of alkalis.

A

1: Alkalis have a bitter taste and soapy feel.
2: Alkalis turn red litmus paper blue.
3: Alkalis produce hydroxide ions when dissolved in water.
4: All alkalis react with acids to form a salt and water only.
5: Alkalis react with ammonium salts to produce ammonia gas upon heating.
6: Alkalis, when mixed with a salt solution, can produce an insoluble metal hydroxide and a soluble metal salt.

33
Q

With state symbols, write down the balanced equation when ammonia dissolves in water.

A

NH3 (g) + H2O -> <- NH4+ (aq) + OH- (aq)
- reversible arrows
- no such thing as ammonium hydroxide / oxide!

34
Q

State the general word equation when an alkali reacts with ammonium salt.

A

alkali + ammonium salt -> ammonia + water + salt

35
Q

Describe the test for ammonia gas.

A

If a colourless, pungent gas that turns damp red litmus paper blue is produced, ammonia gas is produced.

36
Q

Describe the precipitation reaction and state its function.

A

Precipitation reaction: Alkalis react with a salt solution to produce an insoluble metal hydroxide and a soluble metal salt.
Function: To identify cations, with the insoluble metal hydroxide precipitating out of the reaction mixture.

37
Q

Name two types of uses for the following bases.
1: ammonia solution
2: calcium oxide
3: magnesium hydroxide
4: sodium hydroxide

A

1: window cleaning / fertiliser
2: (quicklime) neutralising acidic soil / make iron and cement
3: toothpaste to neutralise acid on teeth / antacids to relieve indigestion
4: soaps / detergents

38
Q

Write an equation in terms of pH and pOH at 25°C.

A

pH + pOH = 14

39
Q

An aqueous solution contains 1.0 * 10^-5 mol dm^-3 of hydrochloric acid. Calculate the concentration of H+ in mol dm^-3, and hence the pH of this solution at 25°C.

A

HCl -> H+ (aq) + Cl- (aq)
[H+] = [HCl] = 1.0 * 10^-5 mol dm^-3 (answer)
pH = -lg [H+] = -lg (1.0 * 10^-5) = 5.00 (answer)

40
Q

An aqueous solution contains 0.10 mol dm^-3 of calcium hydroxide (a strong base). Calculate the concentration of OH- in mol dm^-3, and hence the pH of this solution at 25°C.

A

Ca(OH)2 (aq) -> Ca 2+ (aq) + 2OH- (aq)
[OH-] = 2 * [Ca(OH)2] = 0.200 mol dm^-3 (answer)
pOH = -lg [OH-] = -lg 0.2 = 0.699
pH = 14 - pOH = 14 - 0.699 = 13.3 (answer)

41
Q

State 3 indicators to determine the pH of a solution.

A

Universal Indicator, phenolphthalein, methyl orange

42
Q

Describe how the colour of a Universal Indicator changes from pH 0 to 14.

A

from 0 to 2: red
from 3 to 4: orange
from 5 to 6: yellow
from 7 to 8: green
from 9 to 11: blue
from 12 to 14: violet / purple

43
Q

State the colour changes of methyl orange and phenolphthalein respectively when the solution turns from acidic to neutral to alkaline.

A

methyl orange: red to orange to yellow
phenolphthalein: colourless to pale pink to pink

44
Q

Define an oxide.

A

An oxide is a compound of oxygen and another element.

45
Q

List all the types of oxides.

A

Acidic, basic, amphoteric and neutral oxides.

46
Q

What constitutes an acidic oxide?

A

Oxygen and a non-metal

47
Q

State the property of acidic oxides.

A

Acidic oxides react with alkalis to form a salt and water.

48
Q

What constitutes a basic oxide?

A

Oxygen and a metal

49
Q

State 2 properties of basic oxides.

A

1: Basic oxides are solids at room temperature.
2: Basic oxides react with acids to form a salt and water.

50
Q

What are amphoteric oxides?

A

Amphoteric oxides are metallic oxides that react with both acids and bases to form salts and water.

51
Q

List 3 examples of amphoteric oxides.

A

Zinc oxide (ZnO), aluminium oxide (Al2O3), lead(II) oxide (PbO)
Acronym: ZAP

52
Q

Name the salt and its formula when sodium hydroxide reacts with the following oxides.
1: aluminium oxide
2; lead(II) oxide
3: zinc oxide

A

1: sodium aluminate, NaAl(OH)4
2: sodium plumbate, Na2Pb(OH)4

Chemistry (12 decks)

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