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A-Level Chemistry > Chapter 4 Acids and Redox > Flashcards

Chapter 4 Acids and Redox Flashcards

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1
Q

What do all acids contain?

A

hydrogen -> release H+ ions into the solution when dissolved in water

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2
Q

Strong acid

A

Releases all its hydrogen atoms into solution as H+ ions and completely dissociates in aqueous solution

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3
Q

Weak acid

A
  • Releases a small proportion of its available hydrogen atoms into solution as H+ ions
  • Partially dissociates in aqueous solution
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4
Q

Example of a strong acid

A

hydrochloric acid

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5
Q

Example of a weak acid

A

Ethanoic acid -> only releases the H on the COOH group

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6
Q

Bases

A

A substance which readily accepts H+ ions

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7
Q

Examples of bases

A
  • Metal oxide
  • Metal hydroxides
  • Metal carbonates
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8
Q

Alkali

A
  • A soluble base
  • Dissolves in water, releasing OH- ions into the solution
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9
Q

Neutralisation

A
  • When the H+ ions (of an acid) react with a base to form a salt and neutral water
  • The H+ ions from the acid are replaced by metal or ammonium ions from the base
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10
Q

Equations

A
  • Metal + acid -> salt + hydrogen
  • Alkali + acid -> water + salt
  • Base + acid -> water + salt
  • Carbonate + acid -> Water + carbon dioxide + salt
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11
Q

Titration

A

A technique used to accurately measure the volume of 1 solution that reacts exactly with another solution

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12
Q

What can titrations be used for?

A
  • Finding the concentration of a solution
  • Identification of unknown chemicals
  • Finding the purity of a substance
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13
Q

Volumetric flask

A

Used to make up a standard solution very accurately

  • come in different sizes
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14
Q

Process of preparing a standard solution

A
  1. The solid is weighed accurately
  2. Solid is dissolved in a break using a little distilled water
  3. This solution is transferred to a volumetric flask
  4. The last traces of the solution is rinsed with distilled water
  5. The flask is filled up to the graduation line (bottom of meniscus) on the volumetric flask with distilled water
  6. The volumetric flask is slowly inverted several times to mix the solution thoroughly
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15
Q

What would happen if you didn’t invert the volumetric flask

A
  • Titration results would be inconsistent
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16
Q

Apparatus for acid-base titrations

A
  • Pipette
  • Burette
17
Q

The acid-base titration procedure

A
  1. Add a measured volume of 1 solution to a conical flask using a pipette
  2. Add the other solution to a burette, and take the initial burette reading
  3. Add a few drops of an indicator to the conical flask
  4. Run the solution in the burette into the conical flask, and continuously swirl it to thoroughly mix the 2 solutions
  5. Continue until indicator changes colour = end point
  6. Record final burette reading
  7. Calculate titre = final burette reading - initial burette reading
  8. Repeat until results are concordant
18
Q

The mean titre

A
  • Only use concordant results to keep result accurate
19
Q

Oxidation number

A

Based on a set of rules that apply to atoms

20
Q

Oxidation number of elements

A

0

21
Q

Oxidation number for compounds and ions

A
  • Has an oxidation number
  • The sign is placed before the number
22
Q

Special cases

A
  • H in metal hydrides
  • O in peroxides
  • O bonded to F
23
Q

H in metal hydrides

A

-1

24
Q

O in peroxides

A

-1

25
Q

O bonded to F

A

+2

26
Q

Calculating oxidation numbers

A

Sum of oxidation numbers = total charge

27
Q

Oxidation

A
  • Addition of oxygen
  • Loss of electrons
  • Increase in oxidation number
28
Q

Reduction

A
  • Loss of oxygen
  • Gain of electrons
  • Decrease in oxidation number
29
Q

Oxidising agent

A

Facilitates oxidation by being reduces itself

30
Q

Reducing agent

A

Facilitates reduction by being oxidised itself

31
Q

Redox reactions

A

A reaction where both reduction and oxidation occur

32
Q

What makes a titre more accurate

A
  • Repeat until results are concordant
  • Calculate mean titre from results

A-Level Chemistry (20 decks)

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