WAEC 2018 CHEMISTRY ANSWERS
WAEC 2018 Chemistry expo answers, 2018 Waec Chemistry Expo Answer objective and essay Expo answers now available, Chemistry Waec Expo Answer 2018, Chemistry obj and theory Questions WAEC Ssce Expo Answers Here, Free wassce Chemistry objective, essay & theory correct Expo 2018 answers Runz WAEC Chemistry, WAEC 2018 Free Chemistry essay, obj and theory Questions and Answers Expo for WAEC Chemistry Practical Paper 1 and Paper 2 objective and essay Questions and Answers Expo
(1ai)
Fermentation is the process in which a substance breaks down into a simpler substance. Microorganisms like yeast and bacteria usually play a role in the fermentation process, creating beer, wine, bread, yogurt and other foods.
(1aii)
Zymase
(1b)
-The strength of an acid
-The PH of the solution
(1c)
Fe+H2SO4->FESO4 + H2
H2SO4=10cm^3
Concentration=1mol/dm^3
Amount=Vol * Concentration
=10/100*1
=0.01mol
1mol=56g
0.01mol=56*0.01
=0.56g
Mass of unreacted=5-0.056
=4.44g
(1d)
(i) NaOH(aq)
(ii) Poly-propenitrite
(1e)
A catalyst increases the rate of a chemical by swinging it's activation every.
(1f)
(i) CH3CooH + NH3 ---->CH3CooH2 + H2O
(ii) Ethanoamide
(1g)
(a) It doesn't corrode easily.
(b) it doesn't react with contain inside.
(c) It can stand for a long period of time.
(1h)
(a) Sweet production industries
(b) perfume industries.
(1i)
(a) E
(b)
(1j)
(a) it increases the volume water in ocean and seas.
(b) It causes increase in rainfall and also corrode painted surfaces
(2ai)
Collision theory states that the rate of a reaction depends on the rate of collision of the reactant molecules. Hence effective collision determines the rate of the reaction because it is the collision that leads to the formation of a product.
(2aii)
When the rate of collision increases, the rate at which molecules collide with each other will also increase thereby making the kinetic energy of the molecules to also increase. The temperature will also increase because temperature is a measure of average kinetic energy.
(2bi)
Draw your diagram
(2bii)
C2H5OH + 3O2 ---->2CO2 + 3H2O
1mole of ethanol = 3moles of O2
2.5moles of ethanol will require 3 × 2.5/1 = 7.5moles of O2.
but 1 mole of gas = 22.4dm3
7.5moles = 7.5 × 22.4 = 168dm3 of O2.
(2Ci)
Esterification is the formation of an Ester by the reaction between Alkanol and an acid.
(2cii) Two uses of alkanols
(i) They are used as solvents for cellulose
(ii) They are uses in making perfumes and cosmetics.
(iii) They are used for quick drying of paints and nail varnishes.
(2ciii)
Sodium Ethanoate
(2di)
Tin
(2dii )
This is because the galvanized plate is corrosion-resistant. It has a protective coating which prevents further oxidation of the metal.
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(4ai)
DRAW THE DIAGRAM
(4aii)
Na2SO3(aq) +2HCl(aq) ->2NaCl(aq)+H2O(l)+SO2(g)
(4aiii)
Dry the gas evolved by passing it through H2SO4 and collect it by downward delivery
(4aiv)
Because it is denser than air
(4bi)
It states that there is a mixture of gases which do not react chemically together,then the total pressure exerted by the mixture is the sum of the partial pressure of the individual gases that make up the mixture
(4bii)
T1=12C=285K
P1=690mmHg
V1=30cm^3
T2=273K
P2=760mmHg
V2=?
Using general gas law
V1P1/T1=V2P2/T2
V2=V1P1T2/T1P2
=(30*690*273)/(285*760)
V2=26cm^3
(4ci)
Cl2(g)+H20(l)->HCl(aq)+HOcl(aq)
2HOCl(sunlight)->2HCl(aq+O2(g)
(4cii)
Litmus turns red because of the presence of acid HCl
(4di)
Chlorine->Bromine->iodine (increasing boiling point)
(4dii)
Because water has two lone pairs of electrons as compared to ammonia which has one
(1d)
(i) NaOH(aq)
(ii) Poly-propenitrite
(1e)
A catalyst increases the rate of a chemical by swinging it's activation every.
(1f)
(i) CH3CooH + NH3 ---->CH3CooH2 + H2O
(ii) Ethanoamide
(1g)
(a) It doesn't corrode easily.
(b) it doesn't react with contain inside.
(c) It can stand for a long period of time.
(1h)
(a) Sweet production industries
(b) perfume industries.
(1i)
(a) E
(b)
(1j)
(a) it increases the volume water in ocean and seas.
(b) It causes increase in rainfall and also corrode painted surfaces
(2ai)
Collision theory states that the rate of a reaction depends on the rate of collision of the reactant molecules. Hence effective collision determines the rate of the reaction because it is the collision that leads to the formation of a product.
(2aii)
When the rate of collision increases, the rate at which molecules collide with each other will also increase thereby making the kinetic energy of the molecules to also increase. The temperature will also increase because temperature is a measure of average kinetic energy.
(2bi)
Draw your diagram
(2bii)
C2H5OH + 3O2 ---->2CO2 + 3H2O
1mole of ethanol = 3moles of O2
2.5moles of ethanol will require 3 × 2.5/1 = 7.5moles of O2.
but 1 mole of gas = 22.4dm3
7.5moles = 7.5 × 22.4 = 168dm3 of O2.
(2Ci)
Esterification is the formation of an Ester by the reaction between Alkanol and an acid.
(2cii) Two uses of alkanols
(i) They are used as solvents for cellulose
(ii) They are uses in making perfumes and cosmetics.
(iii) They are used for quick drying of paints and nail varnishes.
(2ciii)
Sodium Ethanoate
(2di)
Tin
(2dii )
This is because the galvanized plate is corrosion-resistant. It has a protective coating which prevents further oxidation of the metal.
=-=-=-=-=-=-=-=-=-=-=-=-=-=
(4ai)
DRAW THE DIAGRAM
(4aii)
Na2SO3(aq) +2HCl(aq) ->2NaCl(aq)+H2O(l)+SO2(g)
(4aiii)
Dry the gas evolved by passing it through H2SO4 and collect it by downward delivery
(4aiv)
Because it is denser than air
(4bi)
It states that there is a mixture of gases which do not react chemically together,then the total pressure exerted by the mixture is the sum of the partial pressure of the individual gases that make up the mixture
(4bii)
T1=12C=285K
P1=690mmHg
V1=30cm^3
T2=273K
P2=760mmHg
V2=?
Using general gas law
V1P1/T1=V2P2/T2
V2=V1P1T2/T1P2
=(30*690*273)/(285*760)
V2=26cm^3
(4ci)
Cl2(g)+H20(l)->HCl(aq)+HOcl(aq)
2HOCl(sunlight)->2HCl(aq+O2(g)
(4cii)
Litmus turns red because of the presence of acid HCl
(4di)
Chlorine->Bromine->iodine (increasing boiling point)
(4dii)
Because water has two lone pairs of electrons as compared to ammonia which has one
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