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Chemistry form 4 > chap 6 - acid > Flashcards

chap 6 - acid Flashcards

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1
Q

what are acids?

A

chemical substances that ionise in water to produce hydrogen ions

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2
Q

what does basicity of acids refer to

A

it refers to the number of hydrogen ions that can be produced by an acid molecule

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3
Q

name the three basicity of acids

A

monoprotic
diprotic
triprotic

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4
Q

name the acids you gotta know

A
  1. HCL (hydrochloric acid
  2. H2SO4 (sulphuric acid)
  3. HNO (nitric acid)
  4. CH3COOH (ethanoic acid)
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5
Q

list monoprotic acids

A

nitric acid
hydrochloric acid
ethanoic acid

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6
Q

list diprotic acid

A

sulphuric acid h2so4

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7
Q

list triprotic acids

A

phosphoric acid h3po4

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8
Q

what are alkalis

A

chemical substances that ionise in water to produce hydroxide ions OH-

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9
Q

list the bases you gotta know

A
  1. KOH ( potassium hydroxide)
  2. NaOH (sodium hydroxide)
  3. NH3 (ammonia) (aqueous)
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10
Q

what is a base that is soluble in water called

A

alkali

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11
Q

list the usage of alkalis and acids in daily life

A
  1. tooth paste
    neutralise the acid on teeth
  2. vinegar
    acidic substance used to make pickled chillies
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12
Q

why cant acidic properties be shown when dry

A

because without water, hydrogen ions cant move freely and ionise to produce h+ ions

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13
Q

what is ph

A

a logarithmic measure of the concentration of hydrogen ions in an aqueous solution

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14
Q

what is the formula for pH

A

pH = -log[H+/ mol]

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15
Q

what is the formula for pOH

A

pOH = -log[OH-]

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16
Q

the other formula with the ph and poh

A

pH + pOH = 14

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17
Q

what is the ph value of antacid

A

10

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18
Q

what does the strength of an acid depends on

A

the degree of dissociation or ionisation of the acid in water

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19
Q

what is a strong acid

A

an acid that ionises completely in water to produce a high concentration of hydrogen ions, H+.

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20
Q

why is HCl is a strong acid

A

because all molecules of hydrogen chloride that dissolve in water are ionised completely

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21
Q

what are weak acids

A

an acid that ionises partially in water to produce low concentration of hydrogen ions H+.

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22
Q

why is ethanoic acid a weak acid

A

molecules of ethanoic acid ionise partially in water.

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23
Q

what are strong alkali

A

an alkali that ionises completely in water to produce high concentration of hydroxide ion

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24
Q

list strong alkalis

A

NaOH

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25
Q

what are weak alkalis

A

an alkali that ionise partially to produce low concentration of hydroxide ions

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26
Q

list weak alkalis

A

ammonia solution

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27
Q

name physical properties of acid and alkalis

A

taste
corrosive
pH value
litmus paper

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28
Q

name chemical properties of acids

A

acid react with bases to produce salt and water
acid react with reactive metals to produce salt and hydrogen gas
acid react with metal carbonates to produce salt, water and carbon dioxide gas

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29
Q

name chemical properties of alkalis

A

alkalis react with acids to produce salt and water
when a mixture of alkali and ammonium salt is heated, ammonia gas, NH3 is released
addition of an alkali to most metal ions, will produce an insoluble metal hydroxide precipitate

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30
Q

what is concentration of a solution

A

a measurement that shows the quantity of solute dissolved in a unit volume of solution.

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31
Q

what is the unit for concentration of solution

A

g/dm3 and mol/dm3

32
Q

what is the formula of concentration of solution in unit g/dm3 (mass of solute found in 1dm3 solution)

A

concentration = mass of solute(g) / volume of solution(dm3)

33
Q

what is the formula for concentration in unit mol/dm3 (the number of moles of solute found in 1dm3 solution) (called molarity)

A

molarity (mol/dm3) = number of mole of solute (mole) / volume of solution (dm3)

34
Q

what is the relationship between concentration and molarity

A

bahagi molar mass>

concentration. molarity

35
Q

how to calculate the number of moles of solute dissolved in the solution if its molarity and the volume of solution is known

A 
M = n/v
n = MV
36
Q

what is standard solution

A

a solution known with known concentration
in preparation of standard solution, mass of solute and volume of distilled water are two parameters that have to be measured accurately

37
Q

why is sodium hydroxide not suitable to be used for preparation of standard solution

A

sodium hydroxide is gyroscopic (absorbs water or moisture in the air .
they also absorb carbon dioxide gas to form Na2CO3

this causes difficulty ti determine the exact mass of sodium hydroxide

38
Q

what is the method yo prepare a standard solution of aqueous solutions

A

dilution method

39
Q

what is the dilution method

A

this method involves adding water to a concentrated standard solution, or known as stock solution, to produce a more diluted solution

40
Q

what is the formula for standard solution for aqueous solutions

A

M1 V1/1000 = M2V2/1000

41
Q

what is neutralisation

A

a reaction between an acid and alkali to produce salt and water only

42
Q

list applications of neutralisation in daily life

A

medicine
milk magnesia relieves gastric pain by neutralising the excessive hydrochloric acid in the stomach

hair health
weak alkali in shampoo neutralises acid on hair

dental health
toothpaste contains a base that neutralises lactic acid produced by bacteria in mouth

agriculture
slaked lime which is alkaline is used to treat acidic soil

43
Q

what is the titration method

A

a qualitative analysis method to determine the volume of acid needed to completely neutralise a given volume of alkali and vice versa

44
Q

explain the titration method

A

in acid base titration, a solution of known concentration is added slowly from a burette into a conical flask that contains a volume if alkali of unknown concentration.
titration stops as soon as the acid base indicator changes color
the point in the titration at which the acid-base indicator changes color is called the end point

45
Q

solve one of those numerical problems involving neutralisation

A

aaaa

46
Q

what is salt

A

is an ionic compound formed when the hydrogen ion, H+ from the acid is replaced with the metal ion or the ammonium ion NH4+

47
Q

what is the physical property of salt crystals

A
  • has flat surface, straight sides and sharp vertices
  • has a fixed angle between two adjacent surfaces
  • has a specific geometrical shape such as cube, cuboid, rhombus and prism
  • different crystals have different geometrical shapes
  • same crystals of different sizes still have same geometrical shapes
48
Q

list down the usage of salt in various fields

A

agriculture
ammonium nitrate as fertiliser while iron(II) sulphate is used in pesticides to kill pests and grass

medicine
calcium sulphate as plaster of paris to support broken bones while potassium manganate(VII) is used as antiseptic to treat wounds

food preparation
sodium chloride is used as flavour, sodium bicarbonate is used for raising dough

preservation
sodium benzoate, is used to preserve chilli sauce, tomato sauce and oyster sauce, sodium nitrate is used ti preserve processed meat as sausages

49
Q

what are soluble salts

A

salts that dissolve in water at room temperature

50
Q

what are non soluble salts

A

salts that do not dissolve at room temperature

51
Q

list the four rules of solubility of salt

A

1) NO SPA
2) SUBACAP
3) COPAGMER
4) ALL COH

52
Q

differentiate methods of preparation of salts

A

titration
double decomposition reaction
neutralisation

53
Q

what is the continuous variation method

A

it is used to construct the ionic equation for the formation of insoluble salts

54
Q

explain the continuous variation method

A

in this method, the volume of one solution, A is fixed while solution B is added to the solution A by increasing the volume as shown

the height of the precipitate will increase gradually until it becomes constant

55
Q

describe the empirical formula you got

A

x(ion Pb2+) + y(ion I-) -> Pbx Iy

56
Q

describe the diagram, method, observation and inference of test for oxygen gas

A

method:
1) put two spatulas of solid potassium chlorate (V) KClO into a test tube

2) heat the solid strongly
3) insert glowing wooden splinter into the test tube

observation: wooden splinter ignited
inference: oxygen gas is produced

57
Q

describe the diagram, method, observation and inference of test for hydrogen gas

A

method:

1) put a few pieces of zinc into a test tube
2) add 4cm3 of dilute sulphuric acid
3) place a lighted wooden splinter near the mouth of the test tube.

observation: pop sound is produced
inference: hydrogen gas is produced

58
Q

describe the diagram, method, observation and inference of test for carbon dioxide gas

A

1) put spatula of solid zinc carbonate into the test tube
2) heat the solid strongly
3) flow the gas produced into limewater

observation: limewater turns cloudy
inference: carbon dioxide is produced

59
Q

describe the diagram, method, observation and inference of test for ammonia gas

A
  1. put a spatula of solid ammonium chloride, NH4Cl into a test tube
  2. Add 4cm3 of dilute sodium hydroxide solution into the test tube
  3. heat the mixture slowly
  4. then, place a piece of moist red litmus paper to the mouth of the test tube

observation: red to blue
inference: ammonia/ alkaline gas is produced

60
Q

describe the diagram, method, observation and inference of test for chlorine gas

A

1) put a spatula of powdered manganate(IV) oxide, MnO2 into a test tube.
2) carefully add 2cm3 of concentrated hydrochloric acid
3) heat the mixture slowly
4) place a blue litmus paper to the mouth of the test tube

observation: blue to red
inference: chlorine gas is produced

61
Q

describe the diagram, method, observation and inference of test for hydrogen chloride gas

A

1) put a spatula of solid sodium chloride into a test tube
2) add 2cm3 of concentrated sulphuric acid carefully
3) heat the mixture slowly
4) dip a glass rod into concentrated ammonia solution
5) hold the dipped glass rod into the mouth of the test tube

observation: white fumes is formed
inference: HCl gas is produced

62
Q

describe the diagram, method, observation and inference of test for sulphur dioxide gas

A

method:
1) put a spatula of solid sodium sulphite into a test tube

2) add 4cm3 of dilute hydrochloric acid
3) heat the mixture slowly
4) flow the gas released into acidified potassium manganate (VII) solution
observation: the acidified potassium manganate(VII) solution turns from purple to colourless
inference: SO2 gas is produced

63
Q

describe the diagram, method, observation and inference of test for nitrogen dioxide gas

A

method:
1) put a spatula of solid lead(II) nitrate into a test tube

2) heat the mixture strongly
3) then place a moist blue litmus paper to the mouth of the test tube.

observation: blue>red
inference: NO2 gas is produced

64
Q

what happens to carbonate salts when heated

A

most carbonate salts decompose to produce metal oxides and carbon dioxide gas

65
Q

what happens when nitrate salts are heated

A

decompose to produce metal oxides, nitrogen dioxide gas and oxygen gas

66
Q

what happens when ammonium chloride salt is heated

A

decompose to produce NH3 + HCl

67
Q

what happens when Iron(II) sulphate is heated

A

Fe2O3 + SO2 + SO3

68
Q

if carbon dioxide gas is detected, what kind of salt is it

A

carbonate salt

69
Q

if nitrogen dioxide gas and oxygen gas is detected, what kind of salt is it

A

nitrate salt

70
Q

if ammonia gas is detected, what kind of salt is it

A

ammonium salt

71
Q

what is qualitative analysis of a salt

A

a technique used to identify the cation and anion present in a salt by analysing its physical and chemical properties

72
Q

list the steps for qualitative analysis

A

1) observation on the physical properties of salt
2) effect of heat on salt
3) test for anions and cations
4) confirmatory test for cations and anions

73
Q

what are the physical properties of salts that can be detected

A

solubility

colour

74
Q

what is the formula for memorising the salt colors

A

iron 23 GB
COSUNIBU
COCO GIBU
COCA G TEK

75
Q

what shit is yellow when hot white when cool

A

Zn2+

76
Q

what shit is brown when hot yellow when cold

A

Pb2+

77
Q

what shit is black when hot black when cold

A

cu2+

Chemistry form 4 (8 decks)

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