chap 6 - acid Flashcards
what are acids?
chemical substances that ionise in water to produce hydrogen ions
what does basicity of acids refer to
it refers to the number of hydrogen ions that can be produced by an acid molecule
name the three basicity of acids
monoprotic
diprotic
triprotic
name the acids you gotta know
- HCL (hydrochloric acid
- H2SO4 (sulphuric acid)
- HNO (nitric acid)
- CH3COOH (ethanoic acid)
list monoprotic acids
nitric acid
hydrochloric acid
ethanoic acid
list diprotic acid
sulphuric acid h2so4
list triprotic acids
phosphoric acid h3po4
what are alkalis
chemical substances that ionise in water to produce hydroxide ions OH-
list the bases you gotta know
- KOH ( potassium hydroxide)
- NaOH (sodium hydroxide)
- NH3 (ammonia) (aqueous)
what is a base that is soluble in water called
alkali
list the usage of alkalis and acids in daily life
- tooth paste
neutralise the acid on teeth - vinegar
acidic substance used to make pickled chillies
why cant acidic properties be shown when dry
because without water, hydrogen ions cant move freely and ionise to produce h+ ions
what is ph
a logarithmic measure of the concentration of hydrogen ions in an aqueous solution
what is the formula for pH
pH = -log[H+/ mol]
what is the formula for pOH
pOH = -log[OH-]
the other formula with the ph and poh
pH + pOH = 14
what is the ph value of antacid
10
what does the strength of an acid depends on
the degree of dissociation or ionisation of the acid in water
what is a strong acid
an acid that ionises completely in water to produce a high concentration of hydrogen ions, H+.
why is HCl is a strong acid
because all molecules of hydrogen chloride that dissolve in water are ionised completely
what are weak acids
an acid that ionises partially in water to produce low concentration of hydrogen ions H+.
why is ethanoic acid a weak acid
molecules of ethanoic acid ionise partially in water.
what are strong alkali
an alkali that ionises completely in water to produce high concentration of hydroxide ion
list strong alkalis
NaOH
what are weak alkalis
an alkali that ionise partially to produce low concentration of hydroxide ions
list weak alkalis
ammonia solution
name physical properties of acid and alkalis
taste
corrosive
pH value
litmus paper
name chemical properties of acids
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
name chemical properties of alkalis
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
what is concentration of a solution
a measurement that shows the quantity of solute dissolved in a unit volume of solution.
what is the unit for concentration of solution
g/dm3 and mol/dm3
what is the formula of concentration of solution in unit g/dm3 (mass of solute found in 1dm3 solution)
concentration = mass of solute(g) / volume of solution(dm3)
what is the formula for concentration in unit mol/dm3 (the number of moles of solute found in 1dm3 solution) (called molarity)
molarity (mol/dm3) = number of mole of solute (mole) / volume of solution (dm3)
what is the relationship between concentration and molarity
bahagi molar mass>
concentration. molarity
how to calculate the number of moles of solute dissolved in the solution if its molarity and the volume of solution is known
M = n/v n = MV
what is standard solution
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
why is sodium hydroxide not suitable to be used for preparation of standard solution
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
what is the method yo prepare a standard solution of aqueous solutions
dilution method
what is the dilution method
this method involves adding water to a concentrated standard solution, or known as stock solution, to produce a more diluted solution
what is the formula for standard solution for aqueous solutions
M1 V1/1000 = M2V2/1000
what is neutralisation
a reaction between an acid and alkali to produce salt and water only
list applications of neutralisation in daily life
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
what is the titration method
a qualitative analysis method to determine the volume of acid needed to completely neutralise a given volume of alkali and vice versa
explain the titration method
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
solve one of those numerical problems involving neutralisation
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what is salt
is an ionic compound formed when the hydrogen ion, H+ from the acid is replaced with the metal ion or the ammonium ion NH4+
what is the physical property of salt crystals
- 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
list down the usage of salt in various fields
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
what are soluble salts
salts that dissolve in water at room temperature
what are non soluble salts
salts that do not dissolve at room temperature
list the four rules of solubility of salt
1) NO SPA
2) SUBACAP
3) COPAGMER
4) ALL COH
differentiate methods of preparation of salts
titration
double decomposition reaction
neutralisation
what is the continuous variation method
it is used to construct the ionic equation for the formation of insoluble salts
explain the continuous variation method
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
describe the empirical formula you got
x(ion Pb2+) + y(ion I-) -> Pbx Iy
describe the diagram, method, observation and inference of test for oxygen gas
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
describe the diagram, method, observation and inference of test for hydrogen gas
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
describe the diagram, method, observation and inference of test for carbon dioxide gas
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
describe the diagram, method, observation and inference of test for ammonia gas
- put a spatula of solid ammonium chloride, NH4Cl into a test tube
- Add 4cm3 of dilute sodium hydroxide solution into the test tube
- heat the mixture slowly
- 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
describe the diagram, method, observation and inference of test for chlorine gas
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
describe the diagram, method, observation and inference of test for hydrogen chloride gas
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
describe the diagram, method, observation and inference of test for sulphur dioxide gas
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
describe the diagram, method, observation and inference of test for nitrogen dioxide gas
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
what happens to carbonate salts when heated
most carbonate salts decompose to produce metal oxides and carbon dioxide gas
what happens when nitrate salts are heated
decompose to produce metal oxides, nitrogen dioxide gas and oxygen gas
what happens when ammonium chloride salt is heated
decompose to produce NH3 + HCl
what happens when Iron(II) sulphate is heated
Fe2O3 + SO2 + SO3
if carbon dioxide gas is detected, what kind of salt is it
carbonate salt
if nitrogen dioxide gas and oxygen gas is detected, what kind of salt is it
nitrate salt
if ammonia gas is detected, what kind of salt is it
ammonium salt
what is qualitative analysis of a salt
a technique used to identify the cation and anion present in a salt by analysing its physical and chemical properties
list the steps for qualitative analysis
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
what are the physical properties of salts that can be detected
solubility
colour
what is the formula for memorising the salt colors
iron 23 GB
COSUNIBU
COCO GIBU
COCA G TEK
what shit is yellow when hot white when cool
Zn2+
what shit is brown when hot yellow when cold
Pb2+
what shit is black when hot black when cold
cu2+
