Acids, Bases and Salts Flashcards

1
Q

What does the pH scale do?

A

The pH scale (0 to 14) measures the acidity or alkalinity of a solution and can be measured using universal indicator or a pH probe.

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2
Q

What do acids contain?

A

Hydrogen Ions

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3
Q

What do alkalis contain?

A

Hydroxide Ions

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4
Q

What does the pH scale measure the concentration of?

A

Hydrogen ions in the substance.

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5
Q

What do all acids contain in water?

A

H+ Ions

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6
Q

What does the higher the concentration of H⁺ ions mean?

A

The stronger the acid

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7
Q

What can acids and alkalis be classified as?

A

Dilute or concentrated depending on the amount of water present.

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8
Q

What do dilute acids have more of?

A

More water molecules mixed with the H⁺ ions

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9
Q

What do concentrated acids have fewer of?

A

Fewer water molecules mixed with the H⁺ ions

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10
Q

What does weak/strong refer to?

A

The degree of ionisation of the acid or base. How readily the base releases OH⁻ ions.

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11
Q

What does dilute/concentrated refer to?

A

The amount of substance present. The number of moles of that acid/base in solution.

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12
Q

What do metals at the top of the reactivity series do?

A

React very vigorously and exothermically with dilute acids

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13
Q

Metal + Acid …

A

Metal + Acid –> Salt + Hydrogen

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14
Q

How do you name salts?

A

The first bit of the name comes from the metal in the alkali. The second bit of the name comes from the acid.

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15
Q

Sodium Hydroxide + Hydrochloric Acid …

A

Sodium Chloride

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16
Q

Acid + Alkali…

A

Acid + Alkali –> Salt + Water

17
Q

Acid + Base …

A

Acid + Base –> Salt + Water

18
Q

Acid + Metal carbonate…

A

Acid + Metal carbonate –> Salt + Water + Carbon Dioxide

19
Q

Any neutralisation involves…

A

The reaction of hydrogen ions with hydroxide ions

20
Q

H⁺ + OH⁻

A

H2O

21
Q

What is the chemical test for CO2?

A

Pass it through limewater if the limewater turns cloudy/milky the gas is CO2

22
Q

What is a titration?

A

A method of preparing solutions of soluble salts and a way of determining the actual concentration of solutions of acids or alkalis.

23
Q

How is titration carried out?

A

The acid is put into a burette and the concentration of either the acid or the alkali is known. The acid is then carefully added to the alkali until the indicator changes colour.

24
Q

Formula for Moles

A

Moles = Concentration x Volume

25
Q

What is moles measured in?

A

Mol

26
Q

What is concentration measured in?

A

Mol/dm³

27
Q

What is volume measured in?

A

dm³

28
Q

What does 1dm³ =

A

1dm³ = 1000cm³

29
Q

How do you test for a sulfate?

A

The standard chemical test for sulfate ions involves reacting a solution of the sulfate with a solution of barium chloride. A white precipitate of insoluble barium sulfate is formed.

30
Q

Sodium Sulfate + Barium Chloride

A

Sodium chloride + Barium sulfate

31
Q

How do you prepare a solid insoluble salt?

A

Solid insoluble salts such as barium sulfate can be prepared from precipitate solutions by filtering the solution. The insoluble salt is trapped by the filter paper and the soluble salt solution passes through. The trapped insoluble salt is then washed with distilled water and then dried on the filter paper before being scraped off.

32
Q

How do you prepare a soluble salt?

A

Soluble salts such as magnesium sulfate, can be prepared by reacting an acid such as sulfuric acid with a metal base such as magnesium oxide. As the resultant salt is soluble it cannot be separated using filtration and an evaporation technique must be used.

33
Q

How are small crystals formed?

A

The excess insoluble base is first separated from the soluble salt using filtration before the water is evaporated off using a heat source and an evaporating basin. Small crystals form inside the basin as the water evaporates.

34
Q

How do you test for carbonates?

A

Carbonate react with dilute acids to create CO2. Bubble through limewater.

35
Q

How do you test for sulfate ions?

A

Add dilute hydrochloric acid then barium chloride solution. A white precipitate will form.