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4.3 know what is meant by the term homologous series, functional group and isomerism
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Homologous series- A series of organic compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group, and shows a gradation in physical properties as a result of increase in molecular size and mass. Functional group - A group of atoms responsible for the characteristic reactions of a particular compound. Isomerism - T wo or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties.
4.2 understand how to represent organic molecules using empirical forulae, molecular formulae, general formulae, structural formulae and displayed formulae
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Molecular formula - It tells us the ratio of atoms present in the molecule. It tells us nothing about the structure. e.g.C 4 H 10 Empirical formula - It represents the simplest whole number ratio of atoms of elements in a compound. Structural formula - It shows how the atoms are arranged in the molecule. Displayed formula - It shows all the atoms and all the bonds in the molecule. the symbols for each atom are joined by straight lines. Each line represents a covalent bond General formula - A chemical formula applicable to a series of compounds Example: The general formula of pentane is C n H 2n+2 The molecular formula of pentane is C 5 H 12 The structural formula will be C H 3 C H 2 C H 2 C H 2 C H 3 The condensed structural formula will be C H 2 ( C H 2 ) 3 C H 3
4.1 know that a hydrocarbon is a compund of hydrogen carbon only
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1.25 Be able to write word equations and balanced chemical equations
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Word equations have just the names of the reactants and products involved: Hydrogen + Oxygen > Water H + O > H 2 O ^ 1 oxygen and 1 hydrogen on the left and on the right 2 hydrogen and 1 oxygen -> not balanced Balanced equations are the symbols of the products and reactants including the numbers of each, there must be an equal number of each element on both sides of the equation, if there are not you can alter this by putting the right number in front of a symbol: 2H + O > H2O ^2 hydrogens and 1 oxygen on both sides State symbols: In balanced equations these state symbols go after a element or compound to show what state it is in (S) solid (L) liquid (G) gas (Aq) aqueous/ solid dissolved in liquid
1.35 understand how to carry out calculations involving gas volumes and the molar volume of gas
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At standard temperature and pressure, one mole of any gas will occupy 24000 cm3; also known as 24dm3. Calculating molar volume from mass Example: 976 cm 3 of oxygen was found to have a mass of 1.3 g Calculate the molar volume of oxygen, under these conditions. Volume = mass x no. of moles Mass of oxygen, O 2 , = 32.0 g. Volume of 1 g = 976 ÷ 1.3 Hence, 32 g = (976 ÷ 1.3) × 32 = 24024 cm 3 Answer: 24.0 is the volume of 32.0 g of O 2 .
1.33 calculate empirical and molecular formulae from experimental data
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Calculating Molecular Formula 1 Write the element symbols S O 2 Write the masses or the % of the elements 3.2 g 6.4 g – 3.2 g = 3.2 g 3 Write the A r values of each element 32 16 4 Divide masses by At 3.2 ÷ 32 = 0.1 3.2 ÷ 16 = 0.2 5 Divide by the smallest number 0.1 ÷ 0.1 = 1 0.2 ÷ 0.1 = 2 6 Write the formula SO 2 Calculating Molecular Formula From the empirical formula, you can work out the molecular formula from the relative formula mass (M r ) of the compound. Add up the atomic masses of the atoms in the empirical formula. For example, the empirical formula of a hydrocarbon is CH 2 and its M r is 42. The mass of the atoms in the empirical formula is 14 42 ÷ 14 = 3 so you need to multiply the numbers in the empirical formula by 3 The molecular formula of the hydrocarbon is therefore C 3 H 6 .