Chemistry of Hazardous Materials

1. Lye (sodium hydroxide) solutions are often used to remove mixtures of solidified grease and hair from clogged plumbing. Select the BEST answer which indicates why lye is effective for this purpose?

		A.
		B.
		C.

2. The primary acids in acid rain are sulfuric and nitric acids. When it rains, a chemical reaction between the sulfuric acid (in the rain) and limestone structures will form carbon dioxide, water, and a salt of the metal. This salt is:

3. Di-lithium is composed of two lithium atoms. Which of the following statements regarding di-lithium or lithium is FALSE?

		A.
		B.
		C.

4. A common product of hydrolysis when some substances react with water is hydrogen chloride. Which of the following water reactive substances does NOT produce hydrogen chloride?

5. Which of the following acids is present in soft drinks?

 

6. Is there a regulatory agency that requires employers to provide suitable facilities for quick drenching and flushing of the eyes and body in all areas within a workplace where employees may be exposed to a corrosive material.

7. Which chemical can be used as a fumigant for almond and pistachio nuts. What should be include in the shipping sheet of the chemical when been transported?

8. ____metallic reacts with water and produced _____ gas which initially concentrates around the metal where it self-ignites.

9. ______is a colourless liquid that is mainly used as a chlorinating and dehydrating agent. When it reacts with water, a gaseous hydrochloric acid and aqueous sulfuric acid are produced.

10. _____, is considered a weak acid, reacts with the components of glass, so it is transported in polyethylene or other acid resistant plastic containers.

 

11. The element titanium occurs on earth as titanium (IV) oxide and is found mostly in the mineral called rutile. Rutile is abundant in beach sands in Australia and South Africa. For titanium to be useful, rutile has to be processed to obtain the basic metal form of titanium. Although the process is costly, titanium is gaining popularity as a material for various equipment due to its strength and light weight. One such application is in sports equipment.

a. Explain the chemical process of manufacturing the metal form of titanium.

b. Explain why titanium is a good choice of material for golf clubs. When not in use, discuss at least one precaution to observe when storing clubs?

c. During the fabrication of golf clubs, finely divided titanium is generated, which poses a dangerous risk of fire and explosion. Explain the chemical process involved.

Titanium is processed from rutile (TiO2). The process (Kroll Process) involves four stages which are;

i. chlorination of the ore to titanium(IV) chloride

ii. purification of titanium(IV) chloride

iii. reduction of titanium(IV) chloride to titanium sponge

iv. processing of titanium sponge

 

The chemical processes involved during titanium manufacture are;

Conversion of TiO2 into TiCl4- The rutile (ore) is heated with chlorine and coke at a temperature of about 1000°C.

 

Reduction of the titanium (IV) chloride. TiCl4 is reduced using either magnesium or sodium. Titanium (IV) chloride vapor is passed into a reaction tank containing molten sodium in an argon atmosphere, and the temperature is raised to about 1000°C.

 

Titanium is a good alternative material for golf clubs because it’s strong, light and durable (The Essential Chemical Industry, 2015). Titanium is resistant to chemical or natural element attacks, therefore, it last longer. It is also strong and lightweight. For instance, the average titanium club is only 60% heavier than aluminum and almost half the weight of steel (Hale, 2017). When not in use clubs should be stored in a place that is air-tight to prevent fire because, in the case of a crack on the clubs, the freshly exposed titanium reacts with oxygen and this could cause a fire.

Titanium, in the absence of moisture, burns slowly but evolves much heat. When water is applied on a hot titanium, hydrogen gas may be evolved causing an explosion. Finely divided titanium is a dangerous fire and explosion hazard because of its large surface area for a chemical reaction (between titanium and oxygen). The finely divided metals can become very hot due to heat evolved by the reaction taking place between titanium and air and therefore, ignite causing fire or an explosion.

12. A garage that specializes in foreign cars had a small magnesium fire when a car part was ignited. The mechanic knew from his training that he should not use water but could use a dry powder like a sodium chloride based fire extinguishing powder (MET-L-X) or a graphite based (LITH-X). He knows that the CO2 extinguishing powder is not a good choice.

a. Explain the reasons why the mechanic thinks using CO2 is not a good idea.

b. If MET-L-X or LITH-X is used, a residue could be left on the metal and if cleaned with water, the fire may be rekindled. Explain the chemical process involved in this phenomenon for both types of fire extinguishing powder.

The fire extinguisher containing carbon dioxide cannot be used on an alkali metal fire because CO2 fuels and accelerates the fire. There is also the formation of carbon black (fine particles) which can pose health problems if inhaled (Miller, 2013).

The principle of fire extinguishing using sodium chloride is that the heat of the fire from the burning magnesium causes the dry powder to cake and form a covering layer (a residue) over the burning metal. This cover excludes air and results in extinguishment. It also dissipates the heat from the burning metal. The same case applies; whereby a mixture of ground graphite and 0.5-3% heavy mineral oil is applied on the burning metal. The graphite in the mixture covers the hot metal so as to exclude air from the burning metal and conducts away the heat so rapidly that the temperature of the metal is reduced to below the ignition temperature (Richard, 1994). If water is used to clean the residue of NaCl layer, Na+ will be attracted to the oxygen component of the water molecules, while the Cl_ part is attracted to the hydrogen part of the water molecule. This would cause the sodium chloride to split, and the layer covering the magnesium will dissolve into separate Na+ and Cl- atoms. Therefore, the exposed magnesium might catch fire again.