2.1.4: acids and bases

Question 1

definition of an acid?

Answer 1

release H+ ions in aqueous solutions - proton doners

Question 2

what are common acids?

Answer 2

hydrochloric acid (HCl)
sulphuric acid (H2SO4)
nitric acid (HNO3)
phosphoric acid (H3PO4)
ethanoic acid (CH3COOH)

Question 3

definition of a base?

Answer 3

reacts with the H+ released from acids to neutralise acids - proton acceptors

Question 4

what are common bases?

Answer 4

metal oxides (MgO, CuO)
metal hydroxides (Mg(OH)2, Ca(OH)2)
ammonia (NH3)

Question 5

what’s an alkali?

Answer 5

bases that are soluble in water and release OH- ions

Question 6

what are common alkalis?

Answer 6

sodium hydroxide (NaOH)
potassium hydroxide (KOH)
ammonia (NH3)

Question 7

what’s a strong acid?

Answer 7

acids that completely dissociate when dissolved in water - very little of the reverse reactions happens so nearly all the acid will dissociate (or ionise) in water and nearly all the H+ ions are released

Question 8

what’s a weak acid?

Answer 8

acids that only slightly dissociate when dissolved in water - the backward reaction is favoured so only a small amount of the acid will dissociate in water and only a few H+ ions are released

Question 9

what’s produced in a neutralisation reaction?

Answer 9

a salt and water

a salt is formed when the H+ ion of an acid is replaced by a metal ion/ammonium ion

water is formed when the H+ ions from the acid combines with the OH- ions from the base

Question 10

how do you make a concentrated acid?

Answer 10

dissolve a large amount of acid an a small volume of water

Question 11

how do you make a dilute acid?

Answer 11

dissolve a small amount of acid in a large volume of water

Question 12

why will you see effervescence (bubbles) is an acid + carbonate reaction?

Answer 12

because when a solid carbonate dissolves it produces carbon dioxide

Question 14

how could you decrease apparatus error?

Answer 14

using an apparatus with greater resolution

increase the size of the measurement made

Question 15

how do you calculate percentage error?

Answer 15

(sensitivity error / measurement made on apparatus) x 100

Question 16

formula of hydrochloric acid?

Answer 16

HCl

Question 17

formula of sulfuric acid?

Answer 17

H2SO4

Question 18

formula of nitric acid?

Answer 18

HNO3

Question 19

formula of the salt sodium chloride?

Answer 19

NaCl

Question 20

formula of the salt sodium sulfate?

Answer 20

Na2SO4

Question 21

formula of the salt calcium nitrate?

Answer 21

Ca(NO3)2

Question 22

what’s an anhydrous salt?

Answer 22

a pure salt that doesn’t contain any water

Question 23

what’s a hydrated salt?

Answer 23

a salt in the form of a crystal that contains water molecules

Question 24

how do you determine the formula of a hydrated salt?

Answer 24

1. calculate the moles of the anhydrous salt
2. calculate the moles of water
3. work out the molar ratio