CHEM 1A03 TUTORIAL #4 Oct 1 – Oct. 5, 2012
Questions – Chapter 10
The following problems (1-7) are based on material from Chapter 10 and class notes.
1. Arrange the following in terms of increasing electronegativity:
(a) Mg, N, O, Si,
(b) F, Se, Sn, Te
2- 2- - - -
2. For the following anions: SO , C3 , NO 3 ClO , 3nd ClO 3 2
a) Draw Lewis structures and resonance forms
b) What are the average bond orders for the central-atom-to-oxygen bonds in these species?
c) What is the average formal charge on the oxygen atoms in each of these species?
d) Indicate whether the species is an exception to the octet rule (i.e. it has more than an octet of
electrons around one of the atoms).
e) Give the VSEPR AB E classes
f) Predict the shapes of the anion.
3. Oxalic acid, (COOH) 2, has two ionizable hydrogens and contains a carbon-carbon single
bond. When one mole of oxalic acid reacts with one mole of calcium hydroxide,Ca(OH) , the 2
salt CaC O is formed.
2 4 2-
a) Draw adequate Lewis structures to represent the bonding in the oxalate ion, C O . 2 4
b) What is the average carbon-oxygen bond order in oxalate ion?
c) What is the average formal charge on each oxygen atom in oxalate ion?
d) Give the shape around each C atom in the oxalate ion.
4. Phosphoric acid, H 3PO 4 contains three oxygen-hydrogen single bonds. When one mole of
phosphoric acid reacts with one mole of sodium hydroxide, the salt sodium dihydrogen
phosphate, NaH PO 2 re4ults.
a) Draw adequate Lewis structures for H PO an3 H 4O . 2 4-
b) Calculate bond orders for all the phosphorus-oxygen bonds of H 3PO 4nd - PO2 4
c) Calculate the formal charges on each oxygen atom in H PO and 3 PO4. 2 4
5. A gaseous molecule "X" is made by burning sulfur in air. "X" is converted to