Organic Chemistry Answers

B: Lewis structures and molecular shape

1. Determine the Lewis structure of trichloromethane/formaldehyde/methanol.

Trichloromethane

O Formaldehyde

 Z Methanol

2. Predict its molecular shape: you must include a sketch along with bond angles.

3. construct a model of the molecule. Take a snapshot of your model and insert it into

the space provided.

4. Show bond polarities and state whether the molecule is a polar molecule.

B: Lewis structures and molecular shape

1. Determine the Lewis structure of trichloromethane/formaldehyde/methanol. The

compound you select will depend on the first letter of your surname as follow:

 A – F Trichloromethane

 G – O Formaldehyde

 P – Z Methanol

2. Predict its molecular shape: you must include a sketch along with bond angles.

3. Use Styrofoam spheres/play dough/any other available and appropriate material to

construct a model of your molecule. Take a snapshot of your model and insert it into

the space provided.

4. Show bond polarities and state whether the molecule is a polar molecule.

Compare different stereoisomers of the same molecular formula, considering any difference in physical or chemical properties that exist.

The reaction scheme that you propose must allow you to identify your five chosen metal complexes, indicating colours observed and the absence or presence of a precipitate when certain reagents are added. As part of your presentation you must explain the underlying chemistry of your scheme and the reactions involved (ie What is ligand substitution and how does it happen? Why and how do colour changes take place? Why and how does a precipitate form? Why does it sometimes re-dissolve?). Include balanced equations for all reactions.

• how is a reaction scheme done?

Identify the dominant intermolecular forces for each mixture.

NaCl/water

naphthalene/kerosene

napthalene/acetone

Kerosene/acetone

kerosene/ethanol

Ethanol/water

Calculate the COD value of wastewater. A 10ml sample of

water was refluxed with 60ml of K2Cr2O7 solution & after

refluxing the excess unreacted dichromate required 24ml of

0.1N FAS solution. A blank of 10ml of d/w of refluxing with

60ml of dichromate solution required 35ml of 0.1N FAS

The dominant intermolecular forces in the mixture of naphthalene/kerosene

What do you mean by 3d⁵

 When 9.0 g of hydrogen gas, H₂, reacts with oxygen gas, O₂, 73.0 g of water is produced.    2H2 + O2 --> 2H2O a) What is the theoretical yield of water? b) What is the percentage yield?

2. Powdered zinc metal reacts with sulphur (S₈) when heated to produce zinc sulphide.

a) What mass of product can be produced with 25 g of zinc?

b) What is the actual yield if the percentage yield was 80%?

3. The thermite reaction has been used to weld railroad rails, make bombs, and ignite solid rocket fuel. The equation of the reaction is:

a) What is the theoretical yield of iron if 100.0 g of Fe₂O₃ is used?

b) What is the percentage yield if 52.3 g of iron is actually produced?

Next you must devise a reaction scheme to identify five specific transition metal complex ions and present this by Powerpoint^® (or another suitable presentation medium) to your colleagues. Your presentation must analyse the reactions that transition metal complexes undergo and demonstrate that you understand the concepts of ligand substitution and acidity. The reaction scheme that you propose must allow you to identify your five chosen metal complexes, indicating colours observed and the absence or presence of a precipitate when certain reagents are added. As part of your presentation you must explain the underlying chemistry of your scheme and the reactions involved (ie What is ligand substitution and how does it happen? Why and how do colour changes take place? Why and how does a precipitate form? Why does it sometimes re-dissolve?). Include balanced equations for all reactions.