Acids and Redox Flashcards

1
Q

What is the oxidation number for elements?

A

It is always 0.

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2
Q

What is the oxidation number of H2?

A

It is still 0 because it is made of the same element.

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3
Q

What does each atom in a compound have?

A

It has an oxidation number.

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4
Q

What is the oxidation number of an ion?

A

This is the same as the charge on the ion but the sign comes before the number.

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5
Q

What is the oxidation number of oxygen when it is in a compound?

A

-2

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6
Q

What is the oxidation number of hydrogen when it is combined with other elements?

A

+1

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7
Q

What is the oxidation number of F when combined with other elements?

A

-1

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8
Q

What is the oxidation number of H in metal hydrides?

A

-1

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9
Q

What is the oxidation number of O in peroxides?

A

-1

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10
Q

What is the oxidation number of oxygen when bonded to fluorine?

A

+2

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11
Q

What is oxidation?

A

This is the addition of oxygen.

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12
Q

What is reduction?

A

This is the removal of oxygen.

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13
Q

What do redox reactions involve?

A

These involve reduction and oxidation.

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14
Q

Is the gain of electrons reduction or oxidation?

A

Reduction is the gain of electrons.

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15
Q

Is oxidation the loss or gain of electrons?

A

Oxidation is the loss of electrons.

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16
Q

What happens to the oxidation number in reduction?

A

It decreases.

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17
Q

What happens to the oxidation number in oxidation?

A

This causes an increase in oxidation number.

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18
Q

What do acids produce in neutralisation reactions?

A

They produce salts.

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19
Q

What happens when dilute acids undergo redox reactions with some metals?

A

They produce a salt and hydrogen gas.

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20
Q

What do acids always contain in their formulae?

A

They always contain hydrogen.

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21
Q

What does the acid release when dissolved in water?

A

It releases hydrogen ions as protons.

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22
Q

What does a strong acid do?

A

It completely dissociates.

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23
Q

What is complete dissociation?

A

This is where the acid releases all of its hydrogen atoms into solution.

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24
Q

What does a weak acid do in an aqueous solution?

A

It partially dissociates.

25
Q

What is meant by partial dissociation?

A

This is where only a small proportion of the available hydrogen atoms are released into the solution.

26
Q

Do organic acids tend to be strong or weak?

A

They tend to be weak.

27
Q

What are 4 types of bases?

A

Metal oxides
Metal hydroxides
Metal carbonates
Ammonia

28
Q

What does a base o?

A

It neutralises an acid to form a salt.

29
Q

Are alkalis bases?

A

Yes

30
Q

What does an alkaline base do?

A

They dissolve in water to release hydroxide ions into the solution.

31
Q

What happens in the neutralisation of an acid?

A

The H+ ions react with a base to form salt and neutral water.

32
Q

What are the H+ ions replaced by in neutralisation reactions?

A

They are replaced by the metal or ammonium ions from the base.

33
Q

What is formed when an acid is neutralised by a metal oxide or metal hydroxide?

A

Salt and water only.

34
Q

What is formed in neutralisation reactions with alkalis?

A

Salt and water.

35
Q

In what type of environment do neutralisation reactions with alkalis take place?

A

The reactants are in solution.

36
Q

What is produced when an acid is neutralised by a carbonate?

A

A salt, water and carbon dioxide gas.

37
Q

What is a titration?

A

This is a technique that is used to accurately measure the volume of a solution that reacts exactly with another solution.

38
Q

What three things can titrations be used for?

A

Finding the concentration of a solution.
Identification of unknown chemicals.
Finding the purity of a substance.

39
Q

What is checking purity an important aspect of?

A

Quality control.

40
Q

What could a small amount of impurity of a drug do to a person?

A

It could cause a great deal of harm to a patient.

41
Q

What is a standard solution?

A

This is a solution of a known concentration.

42
Q

What type of flask is used to make up a standard solution?

A

A volumetric flask is used to make up a standard solution.

43
Q

What should be weighed accurately when preparing a standard solution?

A

The solid..

44
Q

What should the solid be dissolved in when preparing a standard solution?

A

Its should be dissolved in distilled water.

45
Q

What amount of distilled water should be used when dissolving the solid for a standard solution?

A

Less than what will reach the line in the volumetric flask.

46
Q

How should the traces of solution be removed?

A

With distilled water.

47
Q

How should the volumetric flask be filled?

A

By adding water drop by drop until the solution has a meniscus that reaches the graduation line..

48
Q

What should be done once the flask has been filled?

A

The flask should be inverted slowly a few times.

49
Q

Why does the flask need to be inverted?

A

To mix the solution thoroughly for accurate titration results.

50
Q

What type of flask should be used when preparing a standard solution?

A

A volumetric flask.

51
Q

What two things are used in acid-base titrations?

A

A pipette and a burette.

52
Q

In acid-base titrations, what is titrated against what?

A

A solution of an acid is titrated against a solution of a base.

53
Q

hat is a burette reading recorded to?

A

The nearest half division, with the bottom of the meniscus on a mark or between two marks.

54
Q

How many decimal places is the burette read to?

A

2

55
Q

What is the last place of an acid-base titration always either?

A

0 or 5

56
Q

What is important to use when working out the mean titre?

A

It is important to use only the closest accurate titres.

57
Q

How do you get the closest accurate titres?

A

You repeat titres until two agree within 0.10cm.

58
Q

What would happen if all of the titres were included in the mean?

A

You would lose the accuracy of the titration technique.

59
Q

What will you know from the results of the titration?

A

Both the concentration of, C1, and the reacting volume, V1, of one of the solutions.
Only the reacting volume, V2, of the other solution.