A)
a) In most cases the first letter of an element was taken as a symbol for that element. Give two examples of the same.
b) In certain cases the first letter along with its small letter from its name were used as the symbols. Give two examples of the same.
c) I some cases the symbols were derived from their Latin names. Name two metals whose symbols are derived from the same.
d) Sulphur is represented by 'S'. State how the symbol represents the elements
a) qualitatively(i.e , representation in terms of an atom)
b) quantitatively,(representation in terms of weight).
2) Explain the meaning of the terms in Italic given below.
For writing a chemical formula the symbols and the valency of the element or radical should be known :
3) GIVE REASON:
a) In hydrogen chloride the valency of the element chlorine is considered as one.
b) Certain metals exhibit more than one valency hence showing 'variable valency'.
4) Electro positive ions radicals
Symbol/valency name
a. K ¹⁺ potassium
b. Na
c. H
d. NH₄
e. Ca
f. Mg
g. Zn
h. Ba
i. Ni
j. Co
k. Al
l. Cr
Variable valencies
a. Cu ¹⁺
b. Cu
c. Hg ¹⁺
d. Hg
e. Fe ²⁺
f. Fe
g. Mn ²⁺
h. Mn
i. Pb ²⁺
j. Pb
k. Pt ²⁺
l. Pt
Electro negative ions radicals
Symbols/valency Name
a. Cl ¹⁻ Chloride
b. ClO₃
c. ClO
d. Br
e. I
f. OH
g. NO₂
h. NO₃
i. HCO₃
j. HSO₃
k. HSO₄
l. AlO₂
m. MnO₄
n. SO₃
o. SO₄
p. S
q. CO₃
r. O
s. CrO₄
t. Cr₂O₇
u. ZnO₂
v. PbO₂
w. PO₄
x. N
y. C
5) State the valency of each of the elements in the respective compounds in the following:
a) Sulphur in i) sulphur dioxide
ii) sulphur trioxide
b)Nitrogen in i)nitrogen monoxide
ii) Nitrogen dioxide
iii) dinitrogen oxide
iv) dinitrogen pentoxide
c) copper in i) cupric oxide
ii) cuprous oxide
6) complete the following::
The first example has been completed for you...
1. Cr³⁺ SO²⁻
= Cr₂ SO₄ ₃
= Cr₂(SO₄)₃
2. Mg Cl
3. Na ClO₃
4. K ZnO₂
5. Ca PO₄
6. NH₄ SO₄
7. Na HSO₃
8. Al S
9. Zn SO₄
10. Mg O
7) Give the formulas of the following compounds whose metallic radicals exhibits variable valency.
Compound formula
a. cupric nitrate
b. cuprous chloride
c. Iron(II) sulphate
d. Mercuric nitrate
e. Plumbous chloride
f. Stannous chloride
g. Manganese sulphate
h. Platinic chloride
I. Mercurous chloride
j. Iron(III) nitrate
8) Give the names of the compounds whose formulas listed below.
formula name of the compound
a. HNO₂
b. HCO₃
c. H₂C₂O₄
d. H₃PO₄
e. CH₃COOH
f. CaSiO₃
g. Na₂ZnO₂
h. K₂CrO₄
I. Mg₃N₂
9) A chemical equation is a shorthand form for a chemical change
a) 2KClO₃ ∆ -----> 2KCl + 3O₂
i) in the above reaction name the reactant and the products.
ii) State what the arrow in between indicates.
10) GIVE REASON
a) all equations must be balanced.
b) A chemical equation provides Useful information about a reaction.
c) all chemical equations have their limitations.
11) Balancing of equations is carried out by trial and error method. A simple step-by-step balancing is achieved by taking into account the atoms of the same elements of the reactants with the concerned elements of the products.
Balance the following equation in a step-by-step manner...
a) CuO + NH₃ ---> Cu+ H₂O + N₂
b) NH₃+ Cl₂ --> HCl + NCl₃
c) Mg₃N₂+ H₂O --->Mg(OH)₂ +NH₃
d) Pb₃O₄ +HCl---> PbCl₂+H₂O+ Cl₂
12) Write the balanced equations for the following word equations:
a) Manganese(IV) oxide + Hydrochloric acid --> manganese(II) chloride +water+ chlorine.
b) Potassium Hydroxide + Chlorine --> Potassium Chloride+ potassium hypochlorite + water
c) ammonium dichromate --> chromium oxide+ water+ nitrogen
d) potassium sulphide + nitric acid--> potassium nitrate +water + Sulphur Dioxide
e) iron(III) chloride +water+ Sulphur Dioxide---> iron(II) chloride+ sulphuric acid+ hydrochloric acid
f) copper +sulphuric acid--> copper sulphate +water+ Sulphur dioxide.
g) iron(III)oxide +carbon monoxide--> iron+ carbon dioxide.
h) sodium sulphite +sulphuric acid--> sodium sulphate+ water+ Sulphur Dioxide.
I) Zinc+ Sodium Hydroxide--> Sodium zincate + hydrogen
j) aluminium +carbon dioxide--> Aluminium oxide+ carbon
k) sodium bicarbonate+ Aluminium Sulphate -->sodium sulphate +Ammonium hydroxide+ carbon dioxide.
l) calcium hydroxide +Ammonium Sulphate -->calcium sulphate +water+ ammonia
m) nitric acid +magnesium carbonate -->magnesium nitrate + water +carbon dioxide
n) iron(III) oxide+ sulphuric acid --> iron(III) sulphate+ water
o) zinc sulphide+ oxygen--> zinc oxide +Sulphur dioxide.
p) carbon+ nitric acid ---> carbon dioxide + water +Nitrogen dioxide
13) Match the different types of chemical reactions in column II with the meanings of the type of reaction in column I
COLUMN I
a) chemical reaction in which two or more elements or compounds react to form one new compound as a product.
b) A chemical reaction in which a chemical compound decomposes or splits up into two or more simpler substances. It is generally brought about by heat.
c) A chemical reaction which takes place when an element( Or radical) has replaced another element in a compound.
d) A chemical reaction in which two reactants are both decomposed to form new substances by exchanging their radicals.
e) A chemical reaction which employs a catalyst to alter the rate of reaction.
f) A chemical reaction in which the products formed the react together to form the original reactant depending on the conditions of the reaction.
g) A reaction in which a substance dissociates into two or more simpler substances on application of heat and reversible reaction.
h) a reaction which involves addition of oxygen or electronegative element or removal of hydrogen or electropositive element.
I) A reaction which involves of hydrogen or electropositive element or oxygen or removal of oxygen or electronegative element.
j) A chemical reaction which proceeds with evolution of heat energy.
k) A chemical reaction which proceeds with the absorption of heat energy.
l) A chemical reaction which proceeds with absorption of light energy.
COLUMN II
i) Double decomposition
ii) exothermic reaction
iii) reversible reaction
iv) displacement reaction
v) combination or synthesis
vi) decomposition reaction
vii) thermal dissociation
viii) endothermic reaction
ix) catalytic reaction
x) Oxidation reaction
xi) photochemical reaction
xii) reduction reaction
14) State the type of reaction/s to which each of the following belong.
a) Addition of zinc to copper sulphate solution.
b) Heat on lead nitrate crystals.
c) preparation of oxygen from potassium chlorate
d) conversion of ferrous chloride to ferric chloride using chlorine.
e) formation of ammonia from nitrogen and hydrogen.
f) Liberation of hydrogen at the cathode from acidified water.
g) manufacture of glucose by Green plants.
h) formation of nitric oxide from nitrogen and oxygen
I) addition of zinc to dilute sulphuric acid.
j) NH₄Cl <=> NH₃+HCl
k) 2KNO₃ ∆+ 2KNO₂+ O₂
H₃PO₄
l) 2H₂ ------------->2H₂O+ O₂
m) PbBr₂ --> Pb²⁺ + 2Br¹⁻ (ions)
n) 2HgO ∆+ 2Hg + O₂
o) N₂O₄ ∆ <=> 2NO₂
p) AgNO₃ + KCl --> AgCl +KNO₃
q) Fe + S --> FeS
sunlight
r) H₂+ Cl ₂ -------------> 2HCl
s) C + H₂O --> CO + H ₂ - ∆
t) Cl₂+ 2KI --> 2KCl + I₂
∆
u) 3Fe + 4H₂O <=> Fe₃O₄+ 4H₂
v) 2Cu+ O₂ --> 2CuO
w) Fe₂O₃ + 2AI --> Al₂O₃+ 2Fe
x) KNO₃+ H₂SO₄---> HNO₃+KHSO₄
y) 2FeCl₂ + Cl₂ ---> 2FeCl₃
z) Fe + H₂SO₄ ---> FeSO₄ + H₂
a') SO₂ + Cl₂ --> SO₂Cl₂
b') 3Ca + N₂ ---> Ca₃N₂
c') CuSO₄ + Fe --> FeSO₄+ Cu
d') 4HNO₃ --> 2H₂O + 4NO₂ + O₂
15) Find the OXIDATION and REDUCTION reaction as well as REDOX REACTION also find Oxidising AGENT and Reducing AGENT :::
a) Cu+ O₂--> 2CuO
b) CuO+ H₂--> Cu+ H₂O
c) H₂S+ Cl₂ --> S + 2HCl
d) Br₂+ H₂S ---> 2HBr + S
e) 2FeCl₂ + CI₂--> 2FeCl₃
f) 2FeCl₃+H₂S --> 2FeCl₂+ 2HCl+S
g) SO₂+ H₂O + Cl₂ --> H₂SO₄+2HCl
h) 2HgCl₂+SnCl₂ --> HgCl₂+ SnCl₂
i) H₂S+ 2FeCl₃--> 2FeCl₂+2HCl+S
j) 2FeCl₃+ SO₂+2H₂O--> 2FeCl₂++2HCl + H₂SO₄
k) Zn + H₂SO₄--> ZnSO₄+ H₂
l) Fe₂(SO₄)₃+2H₂O+ SO₂--> 2Fe₂SO₄ + 2H₂SO₄
m) Fe + S --> FeS
n)Cl₂+2H₂O+SO₂--> 2HCl+H₂SO₄
o) 2Mg+ SO₂ --> 2MgO +S
p) 2HNO₃ +SO₂--> 2NO₂+H₂SO₄
q) 2H₂S + SO₂ --> 2H₂O
r) 2KMnO₄ +5SO₂--> 2NMnSo₄ + K₂SO₄ + 2H₂SO₄
s) S + 2H₂SO₄--> 3SO₂ +2H₂O
t) K₂Cr₂O₇+H₂SO₄+ 3SO₂--> Cr₂(SO₄)₃+ K₂SO₄ +H₂O
16) Name the following::
a) a coloured gaseous oxidising agent.
b) A liquid oxidizing agent which on thermal decomposition in presence of a catalyst liberates oxygen.
c) a gaseous reducing agent containing oxygen.
d) An acid other than nitric and Sulphuric Acid which is an oxidising agent.
e) A gaseous reducing agent neutral in nature other than carbon monoxide.
f) an oxidising agent which liberates chlorine on heating with concentrated hydrochloric acid.
g) two neutral Gases which react to give a basic and the reaction is exothermic.
h) two neutral gases which react to give a neutral oxide and the reaction is exothermic.
I) A substance which decomposes by absorption of sound energy.
j) two substances which react explosively on close physical contact.
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