The Carbon Group: Exercises and Cases studies

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Chapter: Essentials of Inorganic Chemistry : The Carbon Group

Cases studies: 1. Simethicone 2. Germanium supplements



1. Draw the Lewis structures of the following silicon compounds and compare them with their carbon analogues.

(a)        Silicon dioxide

(b)       Silicon tetrachloride

(c)        Silane

(d)       Trichlorosilane


2. Calculate the ΔEN for all bonds in the following silicon compounds and compare these values with the corresponding carbon bonds.

(a)        Silicon tetrachloride

(b)       Silane

(c)        Trichlorosilane


3. Research and calculate the bond length in the following compounds and compare them with their carbon analogues.

(a)        Silane

(b)       Germane

(c)        Germanium tetrachloride

(d)       Silicon tetrachloride

(e)        Silicon dioxide


Cases studies


1. Simethicone

Simethicone is a silicon-based antifoaming agent that can be found in a variety of formulations.

(a)    Describe the chemical structure of simethicone.

(b)   Research its mode of action and route through the human body.

(c)    Identify clinical applications for simethicone.

(d)   Typical oral suspension used for infants contain simethicone 40 mg/ml. Calculate the weight/volume percentage (%w/v).


2. Germanium supplements

Organic germanium is sold as a dietary supplement and contains mainly bis-carboxyethyl germanium sesquioxide. Despite many positive health claims, several severe side effects including kidney failure have been reported. These side effects are often explained by toxic impurities, and therefore information on the testing procedures can often be found on the packaging. Typical information would read as follows: ‘Analysis performed includes identification by infrared spectroscopy and solubility testing. The purity has been identified by acid group titration and the absence of inorganic germanium has been confirmed by a colour limit test’.

(a)    Draw the chemical structure of bis-carboxyethyl germanium sesquioxide.

(b)   What is the toxic impurity typically found in these preparations?

(c)    What is the solubility of bis-carboxyethyl germanium sesquioxide?

(d)   Describe the results you would expect from the infrared analysis.

(e)    Research a method for the acid base titration mentioned.

(f)     Research the colour limit test for inorganic germanium.


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