Acids and redox

Question 1

Define strong acid and give an example

Answer 1

Releases all its hydrogen atoms into solution as H+ ions and completely dissociates in aqueous solution
E.g. HCl / HNO3

Question 2

Define weak acid and give an example

Answer 2

Only releases a small proportion of its available hydrogen atoms into solution as H+ ions and so partially dissociates in aqueous solution
E.g. CH3COOH / citric acid

Question 3

Give 4 examples of bases

Answer 3

Metal oxides, metal hydroxides, metal carbonates and ammonia

Question 4

What does a base do?

Answer 4

Neutralises an acid to form a salt

Question 5

What are the products formed from acid + alkali?

Answer 5

Salt + water

Question 6

What are the products formed from acid + carbonate?

Answer 6

Salt + water + carbon dioxide

Question 7

What are the products formed from acid + metal oxide / hydroxide?

Answer 7

Salt + water

Question 8

What are the products formed from acid + alkali?

Answer 8

Salt + water

Question 9

What are the products formed from acid + ammonia solution?

Answer 9

Ammonium salts

Question 10

What does it mean to have concordant results?

Answer 10

Results that are within + / - 0.1 ml of each other

Question 11

Give 2 things titration can be used for

Answer 11

• finding the concentration of a solution
• identification of unknown chemicals

Question 12

How do you convert from concentration in moldm^-3 to gdm^-3?

Answer 12

Multiply by the molar mass of the thing you have found the concentration of

Question 13

What is the oxidation number of elements?

Answer 13

0

Question 14

What is the oxidation number of H in metal hydroxides?

Answer 14

-1

Question 15

What is the oxidation number of O in peroxides?

Answer 15

-1

Question 16

What is the oxidation number of O bonded to F?

Answer 16

+2

Question 17

Sum of oxidation numbers = ?

Answer 17

Total charge

Question 18

Define oxidation

Answer 18

Oxidation is the addition of oxygen OR the loss of electrons OR an increase in oxidation number

Question 19

Define reduction

Answer 19

Reduction is the removal of oxygen OR the gain of electrons OR a decrease in oxidation number

Question 20

What is a redox reaction?

Answer 20

A reaction involving both oxidation and reduction

Question 21

What are the products formed from metal + acid?

Answer 21

Salt + hydrogen

Question 22

Define alkali

Answer 22

A base that dissolves in water releasing hydroxide ions into the solution

Question 23

Define acid

Answer 23

A species that release hydrogen ions as protons into solution when dissolved in water

Question 24

Define standard solution

Answer 24

A solution of known concentration

Question 25

What piece of laboratory equipment is used to make up a standard solution?

Answer 25

Volumetric flask

Question 26

What effect would the following error have on the titre?
- The pipette has an air bubble inside

Answer 26

The titre would be less as the solution would be more dilute

Question 27

What can you do to reduce the effect of any random error on a titration?

Answer 27

Repeat the titration until 2 titrations are concordant and then calculate a mean titre from the concordant titres