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  Work ; This is the product of force and the displacement in the direction of the force. Work done = force x distance moved in the direction of force The unit of work done is Joule (J) How to Calculate Work Done Example Questions 1.         If a car of mass 80kg moved a distance of 5m. calculate the work done by the car (g =10m/s 2 )   Solution Mass = 80kg Force = 80 x 10 = 800N Distance = 5m Work done = 800 x 5 = 4000J 2.        A boy pulls a load of 300N to a distance of 6m. Calculate the work done   Solution Force = 300N Distance = 6m Work done = 300 X 6 = 1800J Energy : This is the ability to do work. It is also measured in Joule (J). Energy has many forms which include: ·          Heat energy ·          Light energy ·          Chemical en...

 Titration is the method employed in volumetric analysis. In this method, an unknown concentration of a liquid substance is titrated against another of known concentration. We are going to learn how to calculate the concentration of the substance using the question below. A is a dilute tetraoxosulphate (VI) acid. B contains 2g of sodium hydroxide per 250 cm3 of solution. 25cm 3 of B requires 23cm 3 of A for complete neutralization. Calculate i.                      Concentration of solution B in mol/dm 3 ii.                    Concentration of A in mol/dm 3 iii.                   The number of hydrogen ions in 1dm 3 of solution A (Na=23, H=1, S=32, O=16) Equation of reaction H 2 SO 4(aq...

 Graham’s law states that any gas's diffusion rate at constant temperature and pressure is directly proportional to the square root of its relative molecular mass or vapour density. R 1 /R 2 = √ m 2 / √ m 1                    or t 2 /t 1 = √ m 2 / √ m 1 Example Questions 1.        If 200cm 3 of hydrogen diffused through a porous pot in 30 seconds. How long will it take 400cm 3 of oxygen to diffuse through the same pot? (H = 1, O = 16) Solution Before solving the problem, the first thing is to find how long it will take an equal volume (400cm 3 ) of hydrogen to diffuse through the pot. This is because we are comparing oxygen and hydrogen. Since 200cm 3 of hydrogen = 30s 400cm 3 will = 30/200 X 400 = 60s         t 2 /t 1 = √ m 2 / √ m 1         .t 1 = 60s  ...

 The collision theory shows that the rate of a chemical reaction depends on the frequency of the effective collisions between reactant particles. So any factor that can influence one or all following ·          The energy content of the particles ·          The frequency of the collision of the particles ·          The activation energy of the chemical reaction Can also affect the rate of chemical rate and such factors are ·          Nature of reactants ·          Concentration / pressure(for gas) of the reactants ·          Surface area of reactants ·          Temperature of reaction mixture ·          Presence of light ·     ...

  The rate of a chemical reaction is the number of moles of reactants converted or products formed per unit time. It varies from one chemical reaction to another because some chemical reactions are faster than others. The rate at which a reaction occurs and its control are significant in industries because they are the factors that determine if the reaction will make economic sense or not. How to measure the rate of chemical reaction Consider a reaction between irons and dilute hydrochloric acid Fe (s) + 2HCl (aq) → FeCl 2(aq) + H 2(g) As the reaction proceeds, the iron is used up and iron (II) chloride and hydrogen gas are formed.   The rate of the chemical reaction between iron and the acid can be determined by: ·          Taking a given mass of iron ·          Adding an excess of hydrochloric acid ·          Noting the time taken for a...

This analysis is carried out based on some of the reagents required for the exam. These reagents are listed below: Dilute sodium hydroxide Dilute ammonia solution Barium chloride solution Distilled water Red and blue litmus paper Phenolphthalein Methyl orange One boiling tube Five test tube Source of heat Wash bottle containing distilled water Filtration apparatus The salt to analyse is sodium trioxocarbonate IV which will be tagged C. The sample analysis question below will be used to show the picture of how you can identify the ions in sodium trioxocarbonate IV Question C is a sample of an inorganic compound. Carry out the following test on C and identify any gas evolved. 1.        To a portion of sample C , add distilled water and shake 2.        To the mixture from (1), test with litmus paper, add barium chloride solution, and add dilute HCl in excess. 3.     ...

The calculation of limiting reagents and excess reagents is a real-life application of the stoichiometric relationship between reactants and products. Limiting Reagent : this is the reagent which gets consumed entirely in the chemical reaction. It determines how long a chemical reaction will last or the amount of products to be produced. In other words, the limiting reagent or reactant stops the chemical reaction.  Excess Reagent : this is the reactant that could continue to react if the other reactant is still available for the reaction.  Let us look at this example, and assume that all the requirements of producing a tricycle are three wheels and a wheel steering and a tricycle company has 600 wheels and 250 wheel-steerings for the production of tricycles. Which of the materials will finish first and how many of the other materials will be left over?       3 wheels + 1 steering = 1tricycle The first thing to do is to find the number of tricycles th...