acids and bases

Question 1

definition of an acid

Answer 1

substance that ionises to form hydrogen ions when dissolved in water

Question 2

physical properties of acids

Answer 2

pH <7
sour taste
electrolytes that can conduct electricity

Question 3

strong acids vs weak acids

Answer 3

completely ionises vs partially ionises
reversible vs irreversible reaction
pH 1-3 vs pH 3-7

Question 4

what does higher basicity mean

Answer 4

higher concentration of H+ ions for. the same concentration of acid

Question 5

which metals are unreactive

Answer 5

copper, silver

Question 6

definition of an alkali

Answer 6

substance that dissociates to form hydroxide ions when dissolved in water

Question 7

properties of alkalis

Answer 7

ph >7
bitter taste; slippery and soapy
electrolytes

Question 8

bases vs alkalis

Answer 8

all alkalis are bases, but not all bases are alkalis
bases are insoluble in water while alkalis are soluble in water
bases and alkalis react with acids to produce a salt and water and react with ammonium salts to produce a salt, water, and ammonia

Question 9

how to calculate pH

Answer 9

-lg [concentration of H+ ions]

Question 10

types of oxides

Answer 10

basic oxides (react with acids, metal oxides)
amphoteric oxides (react with both acids and bases) (zinc, aluminium, lead (II)

acidic oxides (react with bases, non-metal oxides)
neutral oxides (react with neither acids nor bases) (water, carbon monoxide, nitric oxide, dinitrogen monoxide)

Question 11

characteristics of oxides across periodic table

Answer 11

change from basic to amphoteric to acidic across a period

Question 12

what is a salt

Answer 12

ionic compound formed by the replacement of one or more hydrogen ions of an acid by a metallic ion of ammonium ion

Question 13

solubility of carbonates in water

Answer 13

all insoluble except sodium, potassium, ammonium

Question 14

solubility of chlorides in water

Answer 14

all soluble except silver, lead (II)

Question 15

solubility of nitrates in water

Answer 15

all soluble

Question 16

solubility of sulfates in water

Answer 16

all soluble except barium, lead (II), calcium (sparingly soluble)

Question 17

how to prepare insoluble salt

Answer 17

precipitation
react 2 aqueous substances

Question 18

how to prepare soluble salts (non spa salts)

Answer 18

reaction of acid with insoluble substance (metal, base, or carbonate)

insoluble substance in excess of acid to ensure salt is not contaminated

Question 19

how to prepare soluble salts (spa salts)

Answer 19

titration (reaction of acid with alkali / soluble carbonate)
both reactants soluble in water, titration allows for exact volume to be used to obtain a pure salt

Question 20

why are spa salts prepared using titration

Answer 20

all their compounds are soluble, hence they cannot be prepared through reactions of acids with insoluble substances

since salt and reactants are soluble in water, using indicator ensures that exact volumes of reactants needed for complete reaction is added with no excess of either reactant, allowing a pure salt to be obtained