Module 2: Chapter 4 (Acids and redox) Flashcards Preview

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Flashcards in Module 2: Chapter 4 (Acids and redox) Deck (25)
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1

What are the formula of 4 common acids?

hydrochloric acid -> HCl
sulphuric acid -> H2SO4
nitric acid -> HNO3
ethanoic acid -> CH3COOH

2

What are the formulae of 3 common alkalis?

sodium hydroxide -> NaOH
potassium hydroxide -> KOH
ammonia -> NH3

3

What are acids?

when dissolved in water an acid releases H+ ions into the solution (dissociation)

4

What is the difference between a strong acid and a weak acid?

- a strong acid completely dissociates in water (HCl, HNO3, H2SO4)
- for a weak acid dissociation is incomplete, written as an equilibrium (carboxylic acid)

5

What is the ethanoate ion?

CH3COO-

6

What is a base?

- metal oxides, metal hydroxides, metal carbonates and ammonia are all classified as bases
- a base neutralises an acid to form a salt

7

What is an alkali?

an alkali is a base that dissolves in water releasing hydroxide ions

8

State the 4 general reactions involving acids

1. acid + alkali -> salt + water
2. acid + metal oxide -> salt + water
3. acid + carbonate -> salt + water + CO2
4. acid + ammonia -> ammonium salt

9

How do you prepare a standard solution in an acid-based titration?

1. solid is weighed accurately
2. solid dissolves in a beaker with distilled water, less than what is needed to fill flask
3. solution is transferred to a volumetric flask (traces are rinsed with distilled water into the flask)
4. flask filled to the graduation line by adding distilled water a drop at a time until the bottom of the meniscus lines up exactly at eye level (if over solution must be prepared again)
5. flask slowly inverted many times to mix solution thoroughly (if not done titration results will be inconsistent)

10

What are the 3 steps for titration calculations?

1. work out the amount, in mol, of the solute in the solution for which you know both the concentration and volume
2. use the equation to work out , in mol, of the solute in the other solution
3. work out the unknown information about eh solute in the other solution

11

Oxidation Rules: simple ions

oxidation number is just the charge on the ion

12

Oxidation Rules: elements

oxidation number for elements not in a compound is zero

13

Oxidation Rules: fluorine

ALWAYS -1

14

Oxidation Rules: oxygen

-2, unless bonded to F or in a peroxide like H2O2

15

Oxidation Rules: chlorine

-1, unless bonded to F or O

16

Oxidation Rules: bromine

-1, unless bonded to F, O or Cl

17

Oxidation Rules: iodine

-1, unless bonded to F, O, Cl or Br

18

Oxidation Rules: hydrogen

+1, unless it's present as a hydride ion

19

Oxidation Rules: group 1 or group 2 metals

group 1 or 2 metals will always be present ions in their compounds so will be +1 and +2

20

Oxidation Rules: compounds

oxidation number of each atom must add up to the charge of the compound

21

Oxidation Rules: sign

sign is put BEFORE the oxidation number, unlike charges

22

What is meant by oxidation?

oxidation is the loss of electrons or increase in oxidation number

23

What is meant by reduction?

reduction is gain of electrons or decrease in oxidation number

24

What is the oxidising agent?

takes electrons from the species being oxidised
- therefore contains the species that is reduced

25

What is the reducing agent?

gives electrons to the species being reduced
- contains the species that is oxidised