Exercises and titanium dioxide Case study

| Home | | Inorganic Pharmaceutical Chemistry |

Chapter: Essentials of Inorganic Chemistry : Organometallic Chemistry

Integrated sun protection in cosmetics is becoming increasingly important. Titanium dioxide nanoparticles are a commonly used as an inorganic UV filter.


Exercises

 

1. Write the electronic configuration for the following elements or ions:

(a)        Ti4+

(b)       Fe2+

(c)        Fe3+

(d)       Ru2+

 

2. What is the oxidation state of the central metal atom in the following complexes?

(a)        [Fe(C5H5)2]+

(b)       TiCl4

(c)        Ti(C5H5)2Cl2

 

3. Draw the energy diagrams displaying the d-orbital splitting for the low and high-spin complexes of the following examples assuming an octahedral complex.

(a)        Fe3+

(b)       Fe2+

(c)        Ti4+

 

4. Predict the geometry of the following complexes:

(a)        Platinum tetrachloride

(b)       Vanadium hexacarbonyl

 

Case study - titanium dioxide

Integrated sun protection in cosmetics is becoming increasingly important. Titanium dioxide nanoparticles are a commonly used as an inorganic UV filter. New formulation techniques allow its integration without the previously known whitening effect. Sunscreens contain typically between 5% and 20% w/v nanosized titanium dioxide.

There are a variety of different methods to analyse the quantity of titanium dioxide in cosmetic formulations. One method is based on the reduction of Ti(+IV) and subsequent re-oxidation with a ferric solution. Titanium dioxide is typically dissolved in hot sulfuric acid and reduced by adding metallic aluminium. The resulting Ti(+III) is then titrated against a standard solution of ammonium iron(III) sulfate in the presence of potassium thiocyanate as indicator.

(a)    Research the type of titration described.

(b)   Describe the chemical structure and mode of action of the indicator.

(c)    Formulate all relevant reaction equations.

(d)   The package states that the sunscreen contains 10% w/v titanium dioxide. For the analysis, a volume containing the theoretical value of 0.5 g of titanium dioxide is dissolved in sulfuric acid and reacted with metallic aluminium. The resulting solution is titrated against a 0.5 M solution of ammonium iron(III) sulfate using potassium thiocyanate as indicator.

For each titration, the following volume of ammonium iron(III) sulfate has been used:

12.55 ml 12.50 ml 12.60 ml

Calculate the real amount of titanium dioxide present in your sample. Express your answer in grams and moles.

(e)    How many millilitres of sunscreen have been used for the analysis?

(f)     Discuss the result in relation to the typically accepted error values.

 

Contact Us, Privacy Policy, Terms and Compliant, DMCA Policy and Compliant

TH 2019 - 2022 pharmacy180.com; Developed by Therithal info.