1) Substances pocess characteristics called properties by which they can be distinguished or identified. From the list of properties given below state which are physical and which are chemical.
a) Thermal conductivity.
b) liquification temperature.
c) Solidification point.
d) Action with indicators.
e) Reaction with dilute acid.
2) Listed below are certain characteristics of physical and chemical changes, identify the correct characteristics for the respective change.
a) loses its identity.
b) changes in form and state.
c) undergoes no change in its fundamental nature .
d) retains its identity.
e) undergoes a temporary change.
f) undergoing the change, changes in mass.
g) evolves or absorbs energy during the change.
h) undergoes change in certain physical properties only.
i) reverts back to original on removal of the change.
j) neither adds nor removes matter from itself.
k) forms at least one new product.
l) releases energy, which is required for completion of the change on reversal of the change.
3) In terms of the factors given below differentiate a physical change from a chemical change occuring in a substance.
a) composition
b) energy
c) mass
4) State whether the following are physical or chemical changes.
a) vaporization.
b) sublimation.
c) liquification
d) fermentation
e) dehydration
f) Putrefaction
g) Rain cycle
h) Carbon cycle.
i) Nitrogen cycle.
j) on magnetization.
k) on rusting.
l) an addition to Copper sulphate solution.
m) burning of a candle.
n) melting of paraffin wax.
o) ripening of a fruit.
p) drying fruit.
q) drying paint.
r) drying of white wash.
s) dissolution of copper sulphate in water .
t) dissolution of carbon dioxide in water.
u) dissolution of iron in dilute HCl
v) passage of current through an electric bulb.
w) passage of current through acidified water.
x) passage of current through copper metal.
z) digestion of food.
a') respiration animals.
b') heat on camphor.
c') heat on Potassium chloride.
d') souring of milk.
e') boiling of milk .
5) Give reasons for the following changes. The reasons should include characteristics such as composition, nature of its change, energy changes or changes in mass of the substance if any.
a) Addition of sodium chloride to water is considered a physical change , while addition of sodium to water a chemical.
b) magnetization of iron is deemed a physical change while addiction of iron to silver nitrate solution and rusting of iron are deemed chemical changes .
c) Heating a platinum wire in a non-luminous flame prior to performance of the flame test is considered a physical change, but heating an iron wire in a bunsen burner is a chemical change.
d) Action of heat on ammonium chloride results in formation of a basic gas and an acidic gas while action of heat on ammonium nitrite result in formation of steam and nitrogen, even then the former is deemed a physical change while the latter a chemical.
e) Heating zinc oxide in a hard glass test tube is a physical change but heating red lead in a test tube or burning of carbon in oxygen or air is deemed a chemical change.
f) Dissolution of sugar in water is physical change while burning of paper is a chemical change.
g) magnetization of iron is a physical change while rusting of iron is a chemical change.
h) Addition of zinc to dilute hydrochloric acid is a chemical change.
i) Change of State of matter is a physical change.
j) Burning and respiration are considered as chemical changes.
k) Photosynthesis is considered a photochemical reaction.
l) Energy released during respiration and burning differ.
6) Differentiation between physical and chemical properties. Classify the following properties as physical or chemical properties.
a) Solubility
b) odour
c) indicator test
d) electrical conductivity
e) dissolution in water
7) Select as Physical/changes
a) Ripening of a fruit
b) curdling of milk
c) melting of wax
d) the carbon cycle
e) separation of two liquids by distillation
f) melting of butter
g) formation of rain
h) boiling of liquid air
i) Composition of the molecules of the substance is altered.
j) change takes place in colour and solubility of substance only.
k) Energy required for completion of the change is released on reversing the change.
l) Matter undergoes changes, but the total mass is unaltered.
m) Change takes place in form or state only.
n) Oxidation of food substance in body cells.
o) Sublimation of iodine
p) Clotting of blood
q) Heat on zinc carbonate
r) Burning of magnesium.
1) Give an example of an endothermic and exothermic reaction.
2) State in each case if the reaction represents oxidation or reduction:
A) Fe⁺⁺ --> Fe⁺⁺⁺
B) Cl⁻ ---> Cl
C) Cu⁺⁺ --> Cu
D) Ag ---> Ag⁺
E) H ---> H ⁺
F) Al --> Al⁺⁺⁺
G) Na --> Na⁺
3) Reaction can be classified as: Direct combination, decomposition, simple displacement, double decomposition, Redox reactions, State which of the following types, takes place in the reactions given below:
A) Cl₂ + 2KI ---> 2Kl + I₂
B) 2Mg + O₂ ---> MgO
C) SO₂+2H₂O+Cl₂-->2HCl +H₂SO₄
D) AgNO₃ + HCl--> AgCl+ HNO₃
E) 4HNO₃ --> 4NO₂ + 2H₂O + O₂
∆
F) CaCO₃ ----> CaO+ CO₂
G) Cl₂ + 2KBr --> 2KCl + Br₂
MnO₂
H) 2H₂O₂ ----------> 2H₂O+ O₂
I) NH₄Cl <=> NH₃ + HCl
J) KNO₃+ H₂SO₄ ---> HNO₃ +KHSO₄
K) CuO+ H₂ ---> Cu + H₂O
7) Give an example each of the following conditions required for a chemical change.
A) closed contact
B) heat
C) light
D) electricity
E) pressure
F) catalyst
8) Name the oxidising agent, reducing agent and the oxidised product in the following:
A) H₂S+2FeCl₃--->2FeCl₂+2HCl+ S
B) H₂S + Cl₂ ---> 2HCl + S
C) 2Cu + O₂ ---> 2CuO
D) H₂S + 2HNO₃ --> 2H₂O+2NO₂ + S
D) 2H₂S + SO₂ ---> 2H₂O + 3S
E) 4HCl+ O₂ ---> 2H₂O + 2Cl₂
9) State the conditions or factors from List 2 which is needed to initiate the chemical change in List 1.
List 1)
A) Formation of lead(II) oxide & oxygen from trilead tetroxide.
2) Formation of a precipitation from AgNO₃ soln. and dil. HCl.
3) Formation of oxygen from potassium Chlorate.
4) Conversion of nitrogen to ammonia using hydrogen.
5) Photosynthesis
List .2
1) light
2) pressure
3) heat
4) catalyst
5) contact
6) sound
10) Match the chemical reactions represented from 1 to 5 with their type from A to J.
1) AB --> A+ B
2) A+ BC --> B + AC
3) AB + XY --> AY + XB
4) AB <=> A + B
5) X - 2 e⁻ ---> X²⁺
A) Synthesis B) Decomposition
C) Oxidation C) Double decomposition D) Catalyst
F) Thermal dissociation
G) Reduction H) Displacement
I) Thermal decomposition
J) Redox
11) Give an example of each of the following energy changes exhibited in a chemical change.
1) An exothermic and an endothermic reaction involving nitrogen as one of the reaction.
2) An exothermic and an endothermic reaction involving Carbon as one of the reactants.
3) A photochemical reaction involving hydrogen as one of the reactants.
4) An electrochemical reaction involving water as the reactant.
5) A photochemical reaction involving a silver salt.
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