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SYLLABUS *Demonstrate an understanding of the terms atom, element, ion, molecule, compound, empirical and molecular formulae *Write balanced equations for simple reactions including the use of state symbols *Demonstrate an understanding of the terms relative atomic mass, amount of substance, molar mass and parts per million *Calculate the amount of substance in a solution of known concentration *Use chemical equations to calculate reacting masses *Use chemical equations to calculate volumes of gases *Use chemical equations to calculate volumes of gases and vice versa using the concepts of amount of substance and molar volume of gases *Use chemical equations and experimental results to deduce percentage yields *Demonstrate an understanding of and be able to perform calculation using the Avogadro constant. *Analyze and evaluate the results obtained from finding a formula of confirming an equation by experiment. *Calculate the percentage yield of product. *Carry out and interpret the results of simple test tube reactions, such as displacements, reactions of acids, precipitations to relate the observations to state symbols used in equations and to practice writing full and ionic equations. PARTICLES AND STRUCTURE The particles The atomic model consists of protons and neutrons in the nucleus, and electrons in shells around the nucleus. Particle Mass Charge Acual/kg Relative to proton Actual/C Relative to proton -27 -19 Proton 1.6726 X 10 1 + 1.6 X 10 +1 Neutron 1.6750 X 10-27 Just over 1 0 0 Electron 9.1095 X 10-31 1/1836 -1.6 X 10-19 -1 The nucleus The protons and neutrons constitute the nucleus. As the number of protons increase, the number of neutrons increase relatively faster, so small atoms have proton and neutron numbers which are comparable, whereas large atoms have many more neutrons than protons. The ration of protons to neutrons is fairly critical, and any departure from the optimum range will lead to nuclear instability and thus radioactivity. Atom ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ………………………………………………………………………….................................................................. Element ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………... 1 Ihavandhoo school/A level note/ Formulae and equations ? Atomic number ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………. Mass number ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… …………………………………………………………………………………………………………………….. Isotopes ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………....................................... All atoms have isotopes. The word comes from the Greek for the same place because all the isotopes of a given atom occupy the same place in the periodic Table defined by the atomic number. Isotopes arise because of changes in neutron number Compound ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… Molecule ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ……………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………........... Relative atomic mass The relative atomic mass, Ar, of an element is defined as the average mass of an atom of the element divided by the mass of 1/12 of the mass of an atom of C-12. Molecular mass Relative molecular mass for a compound is the sum of all the relative atomic masses of the elements which make up the compound`s formula. Molar mass and moles Molecular mass can be expressed in grams. This value is called 1mole. 2 Ihavandhoo school/A level note/ Formulae and equations ? Avogadro constant Number of particles present in one mole of a substance is called Avogadro constant or Avogadro number. It is 6.02 X 1023 Reacting masses Amount of substance in moles = Mass of substance Molar mass Avogadro constant and mole. Equations enable you to calculate how much material to use to get a desired amount of product, whatever the scale. Empirical formula It represent ration of atoms present in a compound. Empirical formula of hydrogen peroxide is HO. Molecular formula It represents number of atoms present in the compound. Molecular formula of hydrogen peroxide is H2O2. Calculation from the equations Amount of the substance of unknown quantity can calculate from known quantity by relating the equations. (Refer the problems) Parts per million Parts per million (PPM). Parts per million works like percent by mass, but is more convenient when there is only a small amount of solute present. PPM is defined as the mass of the component in solution divided by the total mass of the solution multiplied by 106 (one million): Gas xenon ozone nitrogen dioxide Parts per million by volume Volume 0.09 ppmv (9x10-6%) 0.0 to 0.07 ppmv (0%-7x10-6%) 0.02 ppmv (2x10-6%) Greenhouse gases frequently express the concentration of fertilizers, in terms of parts per million (ppm). 3 Ihavandhoo school/A level note/ Formulae and equations ? Could you find out? 1. Write the ionic equations of the following reactions including state symbols. AgNO3 + KCl → AgCl + KNO3. …………………………………………………………………………………………………………. NaOH + HCl → NaCl + H2O. …………………………………………………………………………………………………………. CaCl2 + 2NaOH → Ca(OH)2 + 2NaCl ………………………………………………………………………………………………………….. 2. 0.00005% nitrous acid present in atmosphere. Find out presence of nitrous acid in parts per million. ……………………………………………………………………………………………………………. ………………………………………………………………………………………………………….... …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… 3. A weighed piece of marble is reacted with hydrochloric acid, and is dried and reweighed when all action has ceased. The mass loss was 2.33g; the volume of carbondioxide evolved was 550cm 3. What is the percentage yield of the reaction? CaCO3(s) + 2HCl (aq) → CaCl2(aq) + CO2(g) + H2O(l) ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… 4. Accuracy of the mass of the weighed substances was ±0.03g, find out the percentage error occurs due to the using this balance. …………………………………………………………………………………………………………… ………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… 5. Name the following reactions. BaCl2 + NaOH → Ba(OH)2 + 2NaCl ……………………………………………………………………………………………………… 2NaCl + ZnSO4 → Na2SO4 + ZnCl2 ……………………………………………………………………………………………………… 4 Ihavandhoo school/A level note/ Formulae and equations ?
