Question

Use VSEPR theory to predict the electron-pair geometry and the molecular geometry of the nitrite ion, NO3 - . a. The electron-pair geometry is linear, the molecular geometry is linear. b. The electron-pair geometry is trigonal-planar, the molecular geometry is trigonal planar. c. The electron-pair geometry is trigonal-planar, the molecular geometry is linear. d. The electron-pair geometry is tetrahedral, the molecular geometry is bent. e. The electron-pair geometry is tetrahedral, the molecular geometry is linear

Assume that the following exothermic chemical reaction is at equilibrium. C2H4(g) + ½ O2(g) ⇄ CH2CH2O(g) H = 106.7 kJ mol1 Which one of the following changes will cause the reaction to shift to the left, creating more reactants? a. addition of a catalyst. b. increasing the temperature. c. increasing the pressure. d. introduction of oxygen. e. decrease in temperature explain please

Answer 1

1.

NO₃^-

5 + 3(6) + 1 = 24 electrons

Geometry = 1/2 of ( valence e^- + number of monovalent atoms + charge on anion ).

eg here valence e on central atom (here N) = 5, monovalent atoms = 0 ( oxygen is divalent ) , charge = -1

geometry = 1/2 ( 5 + 1) = 3

i.e sp² trigonal planar.

The nitrate is planar trigonal. Geometry means the shape of the molecule, like where the atoms are placed with respect to each other ,,or you may say the arrangement of atoms in an ion or molecule etc. Here , the N has five bonds that are in resonance(the electrons are not static on any atom but move about symmetrically among the N atom and the O atoms.) however, the atoms themselves are static. If you draw a single resonance str. then there will be two double bonds and a single bond between N & O atoms. The best molecular arrangement with least repulsion between bond is possible with trigonal planar shape and sp2 hybridisation. Simple explaination with text will not help much. Make sure you learn what HYBRIDISATION & VSEPR theory is and how to apply them to any molecule or ion.

Answer is option (b). The electron-pair geometry is trigonal-planar, the molecular geometry is trigonal planar.


Extra - Hope u know
2 = sp = linear
4 = sp³ = tetrahedral
5 = sp³d = trigonal bipyramidal

2.

C2H4(g) + ½ O2(g) ⇄ CH2CH2O(g) $\Delta$ H = - 106.7 kJ mol^-1

The sign of $\Delta$ H is not visible in the reaction. But we know that the combustion of ethene is an exothermic reaction.

So, its an exothermic reaction. Le Chatelier's principle explains that the reaction will proceed in such a way as to counteract the temperature change.

Raising the temperature favors the reverse reaction (endothermic).
Lowering the temperature favors the forward reaction (exothermic).

So, answer is option (b). Increasing in temperature.