# An Introduction to Combustion – Assignment Example

The paper "An Introduction to Combustion"  is a delightful example of an assignment on chemistry. Q5.) The first determinant of the upward movement of a flame or gases is the earth’ s gravitational force. Gravity ensures support of the flame buoyancy. Flames also move upwards to make use of atmospheric oxygen which is fundamental in combustion. Gas density determines its upward movement. If the gas is less dense than air, it will move upwards but if it is denser it will move in the direction of wind or terrain. Qn. 6) The heat needed =thermal conductivity of gypsum  mass in kg temperature change in Kelvin. 220+ 273= 493K. Answer=0.482493= 473.28 Joules Q7.) When gases enclosed in the vessel they are in constant motion with each other.

When the volume of the gases is reduced, their pressure increases which imply an increase in kinetic energy, which is the energy with which the molecules are interacting with each other. As a result, molecules will bombard each other at a higher rate hence increasing the rate of reaction (Cracolice 2011). Q8.) Heat is the kinetic energy (thermal energy) contained in a system or that which is transferred from one system to another.

Heat is measured in terms of metric units known as Joules (J). Transfer of heat is either through radiation, convection or conduction. On the other hand, the temperature is the measure of the average kinetic energy or average molecular motion of particles in a system. The SI units of temperature are Kelvin’ s (K), Celsius (C) and Fahrenheit (F). Another difference is that energy can be transferred from one system to another without the temperature of the substance (Smith 2008). Q9.) Benzene the most common aromatic compound has a molecular formula composed of six carbon atoms bonded by each other by double bonds.

Each carbon is also bonded to one hydrogen atom. Benzene forms a hexagonal ring with each carbon representing a corner of the ring. Within the ring, the double bonds are separated by single bonds which introduce the aspect of the conjugation of bonds (Smith 2008). C6H6 = Qn. 10) Temperature difference = 275° C 32° C=243C. Conversion to Kelvin: 243273= 516 K Heat conduction Q/ Time = (Thermal conductivity) x (Area) x (Thot - Told)/Thickness Answer= (0.480.64516/ 0.032)/3600=1.376 Watts/m2 K. Q11.) There are various kinds of fire extinguisher and they are designed depending on the type of fire involved.

There are six basic categories of fire as listed below: Class A: These fires are caused by ordinary combustible solid materials such as wood, papers, plastics, and cardboards. Class B: Fires caused by combustible or flammable liquids such as kerosene, grease, oil, and gasoline. Class C: These are caused by electrical equipment such as circuit breakers, wiring, and electronic appliances. Class D: Are those that break in chemical laboratories especially due to combustible metals such as sodium, titanium, potassium, and magnesium. Class F: Those that result from flammable gases such as propane methane and butane. Class K: these are fires that occur in restaurants kitchens due to spoilage of cooking oil or fat on electrical cooking appliances. The main fire extinguishers that have been developed as a result of these types of fires are; Water extinguishers: They contain water pressurized with air and used on Class A fires.

They should never be used electrical fires since they accelerate them. Dry chemical extinguishers: They are filled with powder or foam that has been pressurized with nitrogen.

They are appropriate for Class A, B and C fires. The kind of foam contained in them may differ. For instance, some are filled with potassium bicarbonate or sodium bicarbonate which is mildly corrosive on materials and should be wiped off immediately. Carbon Dioxide (CO2) extinguishers: They contain highly pressurized carbon dioxide, a non-flammable gas. They are most appropriate for all kinds of fires including electrical fires and do not leave a harmful residue.