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Application of Gay-Lussac’s Law of Combining Volumes

Gay Lussac’s of combining volumes states that gases react in simple ratio with one another and to volumes of the products provided that temperature and pressure remain constant. In this article, you will understand how to apply this law in calculation by studying the following examples below: 1.     2H 2 + O 2 → H 2 O In the reaction above, what volume of hydrogen would be left over when 300cm 3 of oxygen and hydrogen are exploded in a sealed tube?   1cm 3 of oxygen = 2cm 3 of hydrogen 300cm 3 of oxygen = 2 x 300 = 600cm 3 Volume of left over = 1000 – 600 = 400cm 3 2.     Calculate the volume of carbon (II) oxide required to react with 40cm 3 of oxygen. 2CO + O 2 → 2CO 2 1cm 3 of oxygen = 2cm 3 of CO 40cm 3 of oxygen = 2 x 40 = 80cm 3 3.     Calculate the volume of residual gases that would be produced when 100cm 3 of sulphur (IV) oxide reacts with 20cm 3 of oxygen    2SO 2 + O 2 → 2SO 3 1cm 3 of O 2 = 2cm 3 20cm 3 of O 2 = 2 x 20 = 40cm 3

How to calculate Limiting and Excess Reagents

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 that can be produced by ea

2023 WAEC Possible Volumetric Analysis

  B is a solution of Na 2 CO 3 . nH 2 O prepared by dissolving 5.0g of the hydrated salt in 350cm 3 of solution. A is a solution containing 0.1 moles of hydrochloric acid per dm 3 of solution. a)       Put A into the burette and titrate 20 or 25cm 3 portions of B using methyl orange as an indicator. Record the volume of your pipette. Tabulate your reading and calculate the average volume of acid used. b)       From your results and information given, calculate the i)                     Concentration of B in mole per dm 3 ii)                    Value of Na 2 CO 3 . nH 2 O iii)                  Percentage of water of crystallisation The equation of reaction is Na 2 CO 3 . nH 2 O (aq) + 2HCl (aq) → 2NaCl (aq) + nH 2 O (l) + CO 2(g) ( C =12, O =16 , Na =23,H=1)     Solution The volume of the pipette used = 25.00cm 3 An indicator used = methyl orange                                                                         Titration Burette rea

Possible WAEC 2023 Chemistry Practical Salt Analysis

  There are two samples of compounds to be examined in this coming examination: zinc oxide and glucose. Glucose is tagged C n and zinc oxide is tagged D n .    Glucose is an example of a monosaccharide. It is a strong reducing agent because of the presence of the –CHO group. It is dehydrated to carbon by concentrated tetraoxosulphate (VI) acid like all other carbohydrates.   Zinc oxide is a white insoluble powder which turns yellow when it is hot. As an amphoteric oxide, it can dissolve in both acids and alkalis. Analysis of Glucose The reducing property of glucose can be identified by the following experiments: ·          Its reaction with acidified potassium tetraoxomanganate (VII) solution. Glucose decolorizes acidified potassium tetraoxomanganate (VII) solution from purple to colourless. ·          Its reaction with acidified potassium heptaoxodichromate (VI) solution. Glucose turns acidified potassium heptaoxodichromate (VI) solution from orange to green. ·       

WAEC 2023 Chemistry and Biology specimens

    CHEMISTRY SPECIMEN  In addition to the fitting and reagents normally found in a chemistry laboratory, the following apparatus and materials will be required by each candidate: a)       One burette of 50cm 3 capacity b)       One pipette either 20cm 3 or 25cm 3 ( All candidates at one centre must use  pipette of the same volume. These should be clean and free from grease) c)        The usual apparatus for titration d)       The usual apparatus and reagents for qualitative work including the following with all reagents appropriately labelled                                 I.             Dilute sodium hydroxide solution                               II.             Dilute hydrochloric acid                             III.             Dilute trioxonitratrate (V) acid                             IV.             Silver trioxonitrate (V) solution                               V.             Acidified potassium dichromate solution                             VI