1) State the Valency:
A) Lithium
B) Nickel
C) Ammonium
D) Bromide
E) Sulphite
F) Nitride
G) Carbide
H) Chromium
I) Bisulphate
J) Dichromate
K) Permanganate
2) Write the formula:
A) Sodium zincate
B) Copper (II) carbonate
C) Almunium phosphate
D) Calcium silicate
E) Magnesium nitride
F) Iron(II) sulphate
3) Write the names of the compund
a) KClO b) HClO
c) NaClO₃ d) AlN
e) K₂Cr₂O₇ f) KMnO₄
g) Ca₃N₂ h) Ca₃(PO₄)₂
i) H₂SO₃ j) HCL
k) HNO₃ l) H₂SO₄
m) NH₄OH n) NaOH
n) NaOH o) H₂CO₃
p) HNO₂ q) Mg(HCO₃)₂
r) NaAlO₂ s) K₂PbO₂
t) Cr₂(SO₄)₃ u) Na₂O
4) Balance the equation
a) Mg + N₂ -> Mg₃N₂
b) Fe + H₂O <=> Fe₃O₄ + H₂
c) C₆H₁₂O₆ + O₂ -> CO₂ + H₂
d) Al + H₂O -> Al₂O₃ + H₂
e) Zn + KOH -> K₂ZnO₂ + H₂
f) Fe₂O₃ + C -> Fe + CO
g) CuO + NH₃ -> Cu + H₂O + N₂
h) Pb₃O₄ -> PbO + O₂
i) Zns + O₂ -> ZnO + SO₂
j) H₂SO₄ + S -> SO₂ + H₂O
k) HNO₃ + S -> H₂SO₄ +NO₂+ H₂O
l) MnO₂ + HCl -> MnCl₂ + H₂O + Cl₂
m) Pb₃O₄ + HCl -> PbCl₂+H₂O + Cl₂
n) Ca(HCO₃)₂+HNO₃ -> Ca(NO₃)₂ + H₂O + CO₂
o) Al + NaOH+ H₂O -> NaAlO₂+ H₂
p) H₂SO₄+C-> CO₂+H₂O+SO₂
q) FeSO₄ + O₂ -> Fe₂O₃ + SO₂
r) KMnO₄+HCl-> KCl+MnCl₂+H₂O+ Cl₂
s) K₂Cr₂O₇ + HCl -> KCl + CrCl₃ + H₂O + Cl₂
t) C₁₀H₁₆ + Cl₂ -> C + HCl
u) Fe₂O₃ + CO -> Fe + CO₂
v) Ca(HCO₃)₂+ HNO₃ -> Ca(NO₃)₂ + CO₂ + H₂O
w) Na₂O₂ + H₂O -> NaOH + O₂
x) KOH + Cl₂ -> KCl + KClO₃+ H₂O
y) CaOCl₂+ NH₃ -> CaCl₂+ H₂O+ N₂
z) NaHCO₃ + Al(SO₄)₃ -> Na₂SO₄ + Al(OH)₃ + CO₂.
**
** Underline the compound in each equation given below, which is incorrectly balanced and write the correct balancing for the same..
a) 2NH₄OH + H₂SO₄-->(NH₄)₂SO₄ + 3H₂O.
b) Na₂SO₃ + HCl --> 2NaCl + H₂O+ SO₂
c) CaC₂ + N₂--> 2CaCN₂ + C
d) Fe₂O₃ + 2H₂ --> 2Fe + 3H₂O
e) Cl + 2H₂O + SO₂ --> 4HCl + H₂SO₄
f) 6NaOH + 3Cl₂ --> 6NaCl + NaClO₃ + 3H₂O.
g) C₂H₅OH + 3O₂ --> 2CO₂ + 2H₂O
h) NaOH+ CO₂ --> Na₂CO₃ + H₂O
I) 2H₂O + 2Cl₂ --> 2HCl + O₂
j) 3CuO + NH₃ --> 3Cu + 3H₂O+ N₂
k) PbO₂ + 4HCl ---> PbCl₂ + H₂O+ Cl₂
5) Write the balance the Equation:
A) Potassium nitrate -> Potassium nitrite+ Oxygen
B) Calcium+ water -> Calcium hydroxide+ Hydrogen
C) Iron + Hydrochloric acid -> Iron(II) chloride + Hydrogen
D) Nitrogen dioxide+ Water + Oxygen -> Nitric acid
E) Lead dioxide [lead(IV) oxide] -> Lead monoxide+ Oxygen
F) Aluminium + Oxygen -> Almunium oxide
G) Iron + Chlorine -> Iron(III) chloride
H) Potassium bromide + Chlorine -> Potassium Chloride+ Bromine
I) Potassium bicarbonate-> Potassium carbonate+ water+ Carbon dioxide
J) Calcium hydroxide+ Ammonium Chloride -> Calcium Chloride+ water+ Ammonia.
6) Match the Column I and II
I) 1) Hg⁺² 2) MnO₄¹⁻ 3) Sn⁴⁺ 4) Pb²⁺
5) Sn²⁺ 5) Pb⁴⁺ 6) SO₃²⁻
7) N⁻³ 8) NO₂⁻¹ 9) MnO₄⁻²
10) Hg¹⁺ 11) SO₄²⁻ 12) ClO¹⁻
13) ZnO₂²⁻ 14) Cr₂O₇²⁻
15) CrO₄²⁻ 16) ClO₃¹⁻
II) a) Hypochlorite.
b) Permanganate. c) Plumbous
d) Zincate. e) Nitride. f) Mercuric
g) Stannic. h) Nitrite. i) Sulphite
j) Dichromate
7) Fill the blanks:
A) A symbol represents a short form of a/an ____(atom/element/molecules)
B) Aurum is the Latin name for the metal__(gold/lead/iron/silver)
C) Variable valency is exhibited, since electron are lost from an element from the ___(valence/penultimate) shell.
D) A chemical equation is a shortened form for a ____ (physical/chemical) change.
E) All chemical equations must be balanced to comply with___(Avagadro's law/Law of conservation of matter/Lussac's law).
8) State which of the following formulas of compounds are incorrect. If incorrect Write the Correct formula.
A) (NH₄)₃SO₄ B) NaZnO₂
C) KCr₂O₇ D) NaCO₃
E) Ca₂(PO₄)₃ F) Mg(SO₄)₂
G) KNO₃ H) NaClO
I) NaO J) BaCl₂
9) With reference to a chemical equation state which of the statements 1 to 5 pertain to A or B.
A: information provided by a chemical equation.
B: Limitations of a chemical equation.
1) The nature of the individual elements.
2) The speed of the reaction.
3) The rate of matter in which the substance is present.
4) The completion of the reaction.
5) The direction of the reaction.
10) XCl₂ is the chloride of a metal X. State the formula of the sulphate & the hydroxide of the metal X.
11) An element X is trivalent. Write the balanced equation for the combustion of X in oxygen.
12) The formula of the nitride of a metal X is XN, state the formula of
a) its sulphate
b) its hydroxide.
13) What is the valence of nitrogen
a) NO
b) N₂O
c) NO₂
14) Name three metals whose symbols are derived from
a) the first letter of the name of the element,
b) from their latin names.
15) State the valence of sulphur in
a) SO₂
b) SO₃
16) Give an example of a chemical equation in which two reactants form ---
a) one product
b) two products
c) three products
d) four products.
MnO₂
17) 2KClO₃ -------> 2KCl+ 3O₂[g] - is a balanced equation.
a) State what is a 'balanced equation'.
b) Give a reason why the above equation is balanced.
c) State why the compound MnO₂ is written above the arrow.
18) What do the symbols ---
a) -->
b) <=>
c) (s)
d) (I)
e) (g)
f) (aq.) Present in a chemical equation, mean.
19) CaCO₃ + 2HCl(dil) --> CaCl₂+ H₂O + CO₂(g)
a) State the information provided by the above chemical equation.
b) State the information not conveyed by the above chemical equation.
VALENCY CHART
*********************
ELECTROVALENT POSITIVE IONS/ RADICALS
-----------------------------------------------------
VALENCY 1
Monovalent elements
********************
1) Potassium K¹⁺
2) Sodium. Na¹⁺
3) Lithium Li¹⁺
4) Hydrogen H¹⁺
5) Ammonium. NH₄⁺¹
• Variable valencies
---------
1) Cuprous (Copper[I]) Cu¹⁺
2) Argentous (Silver [I]) Ag¹⁺
3) Mercurous (Mercury[I]) Hg¹⁺ 4) Aurous (Gold [I]) Au¹⁺
VALENCY 2 -- Divalent elements
1) Calcium Ca²⁺
2) Magnesium Mg²⁺
3) Zinc²⁺ Zn²⁺
4) Barium Ba²⁺
5) Nickel Ni²⁺
6) Cobalt Co²⁺
7) Uranium U²⁺
• Variable valencies
1) Cupric (Copper[II]) Cu²⁺
2) Argentic (Silver[II]) Ag²⁺
3) Mercuric (Mercury[II]) Hg²⁺
4) Ferrous (Iron[II]) Fe²⁺
5) Plumbous (Lead[II]) Pb²⁺
6) Stannous (Tin [II]) Sn²⁺
7) Platinous (Platinum[II] Pt²⁺
8)Mangannous(Manganese)[II]) Mn²⁺
VALENCY 3 -- Trivalent elements
1) Aluminium Al³⁺
2) Chromium Cr³⁺
• Variable valancies
1) Ferric (Iron[III]) Fe³⁺
2) Auric (Gold[III]) Au³⁺
VALENCY 4 - Tetravalent elements
• Variable valencies
1) Plumbic (Lead[IV]) Pb⁴⁺
2) Stannic (Tin [IV]) Sn⁴⁺
3) Platinic(Platinum [IV]) Pt⁴⁺
4)Mangannic(Manganese [IV]) Mn⁴⁺
ELECTROVALENT NEGATIVE IONS/RADICALS
----------------------------------------------
VALENCY 1-- Monovalent elements
1) Chloride Cl¹⁻
2) Chlorate. ClO₃¹⁻
3) Hypochlorite ClO¹⁻
4) Bromide Br¹⁻
5) Iodide I¹⁻
6) Hydroxide OH¹⁻
7) Nitrite NO₂¹⁻
8) Nitrate NO₃¹⁻
9) Hydrogen(bi) carbonate HCO₃¹⁻
10) Hydrogen(bi) sulphite HSO₃¹⁻
11) Hydrogen(bi) sulphate HSO₄¹⁻
12) Alluminate AlO₂¹⁻
13) Permanganate MnO₄¹⁻
VALENCY 2-- Divalent elements.
1) Sulphite SO ₃²⁻
2) Sulphate SO₄²⁻
3) Sulphide S²⁻
4) Carbonate CO₃²⁻
5) Oxide O²⁻
6) Chromate CrO₄²⁻
7) Dichromate Cr₂O₇ ²⁻
8) Peroxide O₂²⁻
9) Silicate SiO₃²⁻
10) Zincate ZnO₂²⁻
11) Plumbite PbO₂²⁻
VALENCY 3 -- Trivalent elements:
1) Phosphate. PO₄³⁻
2) Nitride N³⁻
3) Phosphite PO₃³⁻
VALENCY 4 -- Tetravalent elements:
1) Carbide. C⁴⁻
** Compounds formed from elements with variable valency
Element valency Compound form
1)Copper
•Cuprous 1 Copper(I)oxide Cu₂O
• Cupric 2 Copper(II)oxide CuO
2) Iron
• Ferrous 2 Iron(II)oxide FeO
• Ferric 3 Iron(III)oxide Fe₂O₃
3) Mercury
•Mercurous 1Mercuric(I)oxide Hg₂O
• Mercuric 2 Mercury(II)oxide HgO
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