TUTORIAL DAS 12603 SEM 1 SESSI 20122013

DAS 12603

Tutorial 1

1.		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.
2.		Tin (Sn) exists in earth’s crust as SnO2. Calculate the % composition by mass of Sn and O in SnO2.
3.		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?
4.		How many atoms are there in 5.10 moles of sulphur?
5.		How many moles of cobalt (co) atoms are there in 6.00 x 109 (6 billion) Co atoms?
6.		Calculate  the molar mass of the following substance: a) Li2CO3, b) CS2, c) CHCl3, d) C6H8O6  e) KNO3
7.		Calculate the molar mass of a compound if 0.372 mole of it has a mass of 152 g.
8.		How many mlecules of ethane (C2H6) are present in 0.334 g of C2H6
9.		Cinnamic alcohol is used mainly in perfumery, particularly in soaps and cosmetics. Its molecular formula is C9H10O
	(a)	Calculate the % composition by mass of C, H, and O in cinnamic alcohol.
	(b)	How many molecules of cinnamic alcohol are contained in a sample of mass 0.469 g?
10.	(a)	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.
11.	(a)	How many grams of sulphur (S) are needed to react completely with 246 g of mercury (Hg) to form HgS.
12.		What are the empirical formulas of the compounds with the following composition?
	(a)	40.1 % C, 6.6 % H, 53.3 % O.
	(b)	18.4 % C, 21.5 % N, 60.1 % K

Tutorial 2

1.		Compare the physical and chemical properties of metals and non metas.
2.		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.
3.		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.
4.		Define atomic radius. Does the size of an atom have a precise meaning?
5.		How does atomic radius change:
	(a)	From left to right across a period.
	(b)	From top to bottom in group.
6.		Define ionic radius. How does the size of an atom change when it is converted to (a) an anion, (b) cation
7.		Explain why, for isoelectronic ions, the anions are larger than the cations.
8.		Arrange the following atoms in order of decreasing atomic radius: Na, Al, P, Cl, Mg
9.		Which is the largest atom in group 4A?
10.		Which is the smallest atom in group 7A?
11.		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+
12.		List the following ions in order of increasing ionic radius: N3-, Na+, F-, Mg2+, O2-.

Tutorial 3

1.		Write the Lewis structure for nitrogen trifluoride (NF3) in which all three F atoms are bonded to the N atom.
2.		Write the Lewis structure for carbon disulphide (CS2).
3.		Write the Lewis structure for formic acid (HCOOH).
4.		Draw the Lewis structure for the carbonate ion and write the formal charge.
5.		Write the formal charges for the nitrite ion
6.		Draw the resonance structure for the thocyanate ion, SCN-.