- CHEM1012 Worksheet - Lecture 16 1. Consider the bonding in the three nitrogen-containing compounds below. How is N bonded in each case - what types of bonds? To what other atoms? O 0 H : N=N: 0 ? 8 ammonia nitrogen gas nitroglycerine Which of these nitrogen compounds is highly stable, inert and all around us? Which is a key component of nitrogen fertilisers? Which is an explosive? Do you think the bonding in these compounds impacts on how they behave? Yes 2. Nitrogen has an intermediate electronegativity and an odd number of valence electrons. When it bonds to other elements, N can be an electron donor or an electron acceptor depending on the bonding partner. So N has one of the widest ranges of oxidation states of any element. Today we will meet compounds containing nitrogen in oxidation states from -III to +V. Using the rules for assigning oxidation numbers listed below (see also Week 6 Pre-Lecture Quiz), determine the oxidation number of nitrogen in each of the compounds listed below. Remember to apply these rules in the order listed. 1. The oxidation number of an atom in its elemental form is zero; the oxidation number of a monatomic ion is the charge on the ion 2. The sum of the oxidation number for the atoms in a neutral compound equals zero. 3. The sum of the oxidation number for the atoms in a polyatomic ion equals the charge on the ion. 4. The oxidation number of fluorine is -1 (except in F2 where it is 0 by Rule 1). 5. The oxidation number of ions of Group 1 elements is +1. 6. The oxidation number of ions of Group 2 elements is +2. 7. The oxidation number of oxygen is -2 (except in peroxides where it is-1, in 02 & 03 where it is 0 by Rule 1, and in OF2 where the oxidation number of F = - 1 by Rule 4, so 0 = +2). 8. The oxidation number of halogens is usually -1 (except in the pure element (Rule 1) or if bonded to a smaller halogen or O eg CIF2: F = - 1 from Rule 4 so Cl = +2). 9. The oxidation number of His +1 when bonded to non-metals, -1 when bonded to metals. (a) Nitrogen, N2 0 (b) Ammonia, NH3 -3 (c) Hydrazine, N2H4 - 2 (i) Nitric acid, HNO3 + 5 (d) Hydroxylamine, NH2OH -1 (e) Nitrogen trifluoride, NF3 +3 (f) Nitrous oxide, NNO +1 (g) Nitrogen monoxide (nitric oxide), NO (h) Nitrogen dioxide, NO2 +2 +4 (j) Nitrate ion, NO3; +5 (k) Nitrous acid, HNO2 +3
3. If we use octane as our model fuel in an ANFO explosive (ammonium nitrate/ fuel oil), then the unbalanced combustion reaction looks like this: NH?NO3(s) + C8H18(1) > CO2[g] + N2(g) + H2O(g) (1) To balance this equation, the key is to first break it into two parts ... Balance this equation: 2 NH,NO3(s) 1 02(g) + N2(s)+ 4 H20(g)