DAS 12603
Tutorial 1
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1.
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For many years
chloroform (CHCl3) was used as inhalation anesthetic in spie f the
fact that it is also a toxic substance that may cause severe liver, kidney
and heart damage. Calculate the % composition by mass of this compound.
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2.
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Tin
(Sn) exists in earth’s crust as SnO2. Calculate the % composition
by mass of Sn and O in SnO2.
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3.
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Sulfur
(S) is a non-metallic element that is present in coal. When coal is burned,
sulphur is converted to sulphur dioxide and eventually to sulphuric acid that
gives rise to the acid rain phenomenon. How many atoms are in 16.3 g of S?
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4.
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How
many atoms are there in 5.10 moles of sulphur?
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5.
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How many moles of
cobalt (co) atoms are there in 6.00 x 109 (6 billion) Co atoms?
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6.
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Calculate the molar mass of the following substance:
a) Li2CO3, b) CS2, c) CHCl3, d) C6H8O6
e) KNO3
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7.
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Calculate the
molar mass of a compound if 0.372 mole of it has a mass of 152 g.
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8.
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How
many mlecules of ethane (C2H6) are present in 0.334 g
of C2H6
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9.
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Cinnamic alcohol
is used mainly in perfumery, particularly in soaps and cosmetics. Its
molecular formula is C9H10O
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(a)
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Calculate the %
composition by mass of C, H, and O in cinnamic alcohol.
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(b)
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How many
molecules of cinnamic alcohol are contained in a sample of mass 0.469 g?
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10.
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(a)
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Peroxyacylnitrate
(PAN) is one of the components of smog. It is a compound of C, H, N, and O.
determine formula from the following % composition by mass: 19.8 % C, 2.50 %
H, 11.6 % N. what is the molecular formula given that its molar mass is about
120 g.
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11.
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(a)
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How
many grams of sulphur (S) are needed to react completely with 246 g of
mercury (Hg) to form HgS.
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12.
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What
are the empirical formulas of the compounds with the following composition?
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(a)
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40.1
% C, 6.6 % H, 53.3 % O.
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(b)
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18.4
% C, 21.5 % N, 60.1 % K
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Tutorial 2
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1.
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Compare
the physical and chemical properties of metals and non metas.
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2.
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Without
referring to the periodic table, write the name and the symbol for an element
in each of the following groups: 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A, and
transition metals.
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3.
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Without
referring to the periodic table, write the electron configuration of elements
with the following atomic numbers: (a) 9, (b) 20, (c) 26, (d) 33. Classify
the elements.
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4.
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Define
atomic radius. Does the size of an atom have a precise meaning?
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5.
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How does atomic
radius change:
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(a)
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From
left to right across a period.
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(b)
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From
top to bottom in group.
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6.
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Define ionic radius.
How does the size of an atom change when it is converted to (a) an anion, (b)
cation
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7.
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Explain
why, for isoelectronic ions, the anions are larger than the cations.
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8.
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Arrange
the following atoms in order of decreasing atomic radius: Na, Al, P, Cl, Mg
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9.
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Which is the
largest atom in group 4A?
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10.
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Which is the
smallest atom in group 7A?
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11.
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Indicate which
one of the two species in each of the following pairs is smaller: (a) Cl or
Cl-; (b) Na or Na+; (c) O2- or S2-;
(d) Mg2+ or Al3+; (e) Au+ or Au3+
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12.
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List
the following ions in order of increasing ionic radius: N3-, Na+,
F-, Mg2+, O2-.
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Tutorial 3
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1.
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Write
the Lewis structure for nitrogen trifluoride (NF3) in which all
three F atoms are bonded to the N atom.
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2.
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Write
the Lewis structure for carbon disulphide (CS2).
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3.
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Write
the Lewis structure for formic acid (HCOOH).
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4.
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Draw
the Lewis structure for the carbonate ion and write the formal charge.
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5.
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Write the formal
charges for the nitrite ion
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6.
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Draw
the resonance structure for the thocyanate ion, SCN-.
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