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CALCULATIONS INVOLVING FORMULAE National 5 Chemistry KNOCKHARDY PUBLISHING

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CALCULATIONS INVOLVING FORMULAE INTRODUCTION This Powerpoint show is one of several produced to help students understand selected GCSE Chemistry topics. It is based on the requirements of the SQA specification. Individual students may use the material at home for revision purposes and it can also prove useful for classroom teaching with an interactive white board. Accompanying notes on this, and the full range of Chemistry topics, are available from the KNOCKHARDY WEBSITE at... All diagrams, photographs and any animations in this Powerpoint are original and created by Jonathan Hopton. Permission must be obtained for their use in any work that is distributed for financial gain. HOPTON

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CONTENTS CONTENTS Working out simple formulae Relative formula mass Percentage composition Reacting masses Yield and percentage yield CALCULATIONS INVOLVING FORMULAE

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HOPTON chlorine gasCl 2 hydrogen gasH 2 nitrogen gasN 2 oxygen gasO 2 hydrochloric acidHC l nitric acidHNO 3 sulphuric acidH 2 SO 4 sodium hydroxideNaOH sodium chlorideNaC l sodium carbonateNa 2 CO 3 potassium chlorideKC l magnesium oxideMgO magnesium hydroxideMg(OH) 2 magnesium carbonateMgCO 3 magnesium sulphateMgSO 4 calcium carbonateCaCO 3 calcium chlorideCaC l 2 SOME COMMON FORMULAE Many formulae can be worked out by reference to a table of ions. Others just have to be known off by heart. Many formulae can be worked out by reference to a table of ions. Others just have to be known off by heart.

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hydrogen H + chloride C l ¯ sodium Na + bromide Br¯ potassium K + iodide I¯ lithium Li + hydroxideOH¯ rubidium Rb + nitrateNO 3 ¯ caesium Cs + nitrite NO 2 ¯ silver(I) Ag + hydrogencarbonate HCO 3 ¯ ammonium NH 4 + hydrogensulphate HSO 4 ¯ calcium Ca 2+ sulphate SO 4 2- barium Ba 2+ sulphite SO 3 2- magnesium Mg 2+ sulphide S 2- zinc Zn 2+ oxide O 2- iron(II) “ferrous” Fe 2+ carbonate CO 3 2- copper(II) Cu 2+ aluminium A l 3+ iron(III) “ferric” Fe 3+ HOPTON TABLE OF IONS

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hydrogen H + chloride C l ¯ sodium Na + bromide Br¯ potassium K + iodide I¯ lithium Li + hydroxideOH¯ rubidium Rb + nitrateNO 3 ¯ caesium Cs + nitrite NO 2 ¯ silver(I) Ag + hydrogencarbonate HCO 3 ¯ ammonium NH 4 + hydrogensulphate HSO 4 ¯ calcium Ca 2+ sulphate SO 4 2- barium Ba 2+ sulphite SO 3 2- magnesium Mg 2+ sulphide S 2- zinc Zn 2+ oxide O 2- iron(II) “ferrous” Fe 2+ carbonate CO 3 2- copper(II) Cu 2+ aluminium A l 3+ iron(III) “ferric” Fe 3+ HOPTON TABLE OF IONS NUMBER OF ELECTRONS IN OUTER SHELL OF ATOMS

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hydrogen H + chloride C l ¯ sodium Na + bromide Br¯ potassium K + iodide I¯ lithium Li + hydroxideOH¯ rubidium Rb + nitrateNO 3 ¯ caesium Cs + nitrite NO 2 ¯ silver(I) Ag + hydrogencarbonate HCO 3 ¯ ammonium NH 4 + hydrogensulphate HSO 4 ¯ calcium Ca 2+ sulphate SO 4 2- barium Ba 2+ sulphite SO 3 2- magnesium Mg 2+ sulphide S 2- zinc Zn 2+ oxide O 2- iron(II) “ferrous” Fe 2+ carbonate CO 3 2- copper(II) Cu 2+ aluminium A l 3+ iron(III) “ferric” Fe 3+ HOPTON TABLE OF IONS Formulae can be worked out by balancing the charges so that… negative charge = positive charge

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HOPTON CONSTRUCTING FORMULAE

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HOPTON CONSTRUCTING FORMULAE Many formulae can be worked out by balancing the charges so that… negative charge = positive charge

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Q.1 Write out the correct formula for each of the following compounds. a) sodium chloride b) magnesium sulphate c) potassium oxide d) calcium chloride e) copper(II) nitrate sodium ion Na + chloride ion C l ¯ HOPTON CONSTRUCTING FORMULAE

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Q.1 Write out the correct formula for each of the following compounds. a) sodium chloride b) magnesium sulphate c) potassium oxide d) calcium chloride e) copper(II) nitrate sodium ion Na + chloride ion C l ¯ Na + Cl¯Cl¯ HOPTON CONSTRUCTING FORMULAE

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Q.1 Write out the correct formula for each of the following compounds. a) sodium chloride b) magnesium sulphate c) potassium oxide d) calcium chloride e) copper(II) nitrate sodium ion Na + chloride ion C l ¯ Na + Cl¯Cl¯ ONE Na + balances ONE C l ¯ FORMULA is NaC l HOPTON CONSTRUCTING FORMULAE

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Q.2 Write out the correct formula for each of the following compounds. a) sodium chlorideNaC l b) magnesium sulphate c) potassium oxide d) calcium chloride e) copper(II) nitrate magnesium ionMg 2+ sulphate ionSO 4 2- Mg 2+ SO 4 2- HOPTON CONSTRUCTING FORMULAE

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Q.2 Write out the correct formula for each of the following compounds. a) sodium chlorideNaC l b) magnesium sulphate c) potassium oxide d) calcium chloride e) copper(II) nitrate magnesium ionMg 2+ sulphate ionSO 4 2- Mg 2+ SO 4 2- ONE Mg 2+ balances ONE SO 4 2- FORMULA isMgSO 4 HOPTON CONSTRUCTING FORMULAE

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Q.3 Write out the correct formula for each of the following compounds. a) sodium chlorideNaC l b) magnesium sulphateMgSO 4 c) potassium oxide d) calcium chloride e) copper(II) nitrate potassium ion K + oxide ionO 2- K+K+ O 2- K+K+ HOPTON CONSTRUCTING FORMULAE

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Q.3 Write out the correct formula for each of the following compounds. a) sodium chlorideNaC l b) magnesium sulphateMgSO 4 c) potassium oxide d) calcium chloride e) copper(II) nitrate potassium ion K + oxide ionO 2- K+K+ O 2- TWO K + balance ONE O 2- FORMULA isK 2 O K+K+ HOPTON CONSTRUCTING FORMULAE

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Q.4 Write out the correct formula for each of the following compounds. a) sodium chlorideNaC l b) magnesium sulphateMgSO 4 c) potassium oxideK 2 O d) calcium chloride e) copper(II) nitrate calcium ion Ca 2+ chloride ionC l ¯ Ca 2+ Cl¯Cl¯ Cl¯Cl¯ HOPTON CONSTRUCTING FORMULAE

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Q.4 Write out the correct formula for each of the following compounds. a) sodium chlorideNaC l b) magnesium sulphateMgSO 4 c) potassium oxideK 2 O d) calcium chloride e) copper(II) nitrate calcium ion Ca 2+ chloride ionC l ¯ Ca 2+ Cl¯Cl¯ ONE Ca 2+ balances TWO C l ¯ FORMULA isCaC l 2 Cl¯Cl¯ HOPTON CONSTRUCTING FORMULAE

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Q.5 Write out the correct formula for each of the following compounds. a) sodium chlorideNaC l b) magnesium sulphateMgSO 4 c) potassium oxideK 2 O d) calcium chlorideCaC l 2 e) copper(II) nitrate copper(II) ion Cu 2+ nitrate ionNO 3 ¯ Cu 2+ NO 3 ¯ HOPTON CONSTRUCTING FORMULAE

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Q.5 Write out the correct formula for each of the following compounds. a) sodium chlorideNaC l b) magnesium sulphateMgSO 4 c) potassium oxideK 2 O d) calcium chlorideCaC l 2 e) copper(II) nitrate copper(II) ion Cu 2+ nitrate ionNO 3 ¯ Cu 2+ NO 3 ¯ ONE Cu 2+ balances TWO NO 3 ¯ FORMULA isCu(NO 3 ) 2 NO 3 ¯ HOPTON CONSTRUCTING FORMULAE

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Q.5 Write out the correct formula for each of the following compounds. a) sodium chlorideNaC l b) magnesium sulphateMgSO 4 c) potassium oxideK 2 O d) calcium chlorideCaC l 2 e) copper(II) nitrate copper(II) ion Cu 2+ nitrate ionNO 3 ¯ Cu 2+ NO 3 ¯ ONE Cu 2+ balances TWO NO 3 ¯ FORMULA isCu(NO 3 ) 2 NO 3 ¯ NOTE THE BRACKETS If the brackets weren’t there, the formula would appear as CuNO 32 (thirty two oxygens). Brackets are used when the ion has more than one element in it. eg NO 3 ¯ OH¯ NH 4 + NOTE THE BRACKETS If the brackets weren’t there, the formula would appear as CuNO 32 (thirty two oxygens). Brackets are used when the ion has more than one element in it. eg NO 3 ¯ OH¯ NH 4 + HOPTON CONSTRUCTING FORMULAE

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HOPTON Write out the correct formula for each of the following compounds. a) lithium chlorideLiC l b) calcium sulphateCaSO 4 c) sodium oxideNa 2 O d) calcium chlorideCaC l 2 e) iron(II) nitrateFe(NO 3 ) 2 f) potassium sulphateK 2 SO 4 g) calcium hydroxideCa(OH) 2 h) zinc carbonateZnCO 3 i) aluminium oxideA l 2 O 3 j) aluminium sulphateA l 2 (SO 4 ) 3 k) ammonium nitrateNH 4 NO 3 l) ammonium chlorideNH 4 C l m) ammonium sulphate(NH 4 ) 2 SO 4 n) iron(III) chlorideFeC l 3 FORMULAE – Test questions

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Write out the correct formula for each of the following compounds. a) lithium chlorideLiC l b) calcium sulphateCaSO 4 c) sodium oxideNa 2 O d) calcium chlorideCaC l 2 e) iron(II) nitrateFe(NO 3 ) 2 f) potassium sulphateK 2 SO 4 g) calcium hydroxideCa(OH) 2 h) zinc carbonateZnCO 3 i) aluminium oxideA l 2 O 3 j) aluminium sulphateA l 2 (SO 4 ) 3 k) ammonium nitrateNH 4 NO 3 l) ammonium chlorideNH 4 C l m) ammonium sulphate(NH 4 ) 2 SO 4 n) iron(III) chlorideFeC l 3 HOPTON FORMULAE – Test questions

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RELATIVE FORMULA MASS HOPTON

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The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula RELATIVE FORMULA MASS HOPTON

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To calculate this value, it is important that one understands how to work out the number of each type of atom present. The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula RELATIVE FORMULA MASS HOPTON

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To calculate this value, it is important that one understands how to work out the number of each type of atom present. A small subscript number tells you how many there of the atom just before the subscript The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula RELATIVE FORMULA MASS

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To calculate this value, it is important that one understands how to work out the number of each type of atom present. A small subscript number tells you how many there of the atom just before the subscript H 2 O 2 hydrogen atoms 1 oxygen atom (a 1 after the O is unnecessary) The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula RELATIVE FORMULA MASS HOPTON

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To calculate this value, it is important that one understands how to work out the number of each type of atom present. A small subscript number tells you how many there of the atom just before the subscript H 2 O 2 hydrogen atoms 1 oxygen atom (a 1 after the O is unnecessary) Ca(OH) 2 1 calcium atom 2 lots of everything in the bracket ie 2 oxygen atoms and 2 hydrogen atoms (groups of atoms occurring in brackets include… SO 4 NO 3 NH 4 OH) The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula RELATIVE FORMULA MASS

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a) H 2 O2 x H1 x O b) NaOH1 x Na1 x O1 x H c) (NH 4 ) 2 SO 4 2 x N4 x O8 x H1 x S d) Ca(OH) 2 1 x Ca2 x O2 x H e) H 2 SO 4 2 x H4 x O1 x S f) CuSO 4.5H 2 O 1 x Cu10 x H9 x O1 x S RELATIVE FORMULA MASS HOW MANY ATOMS OF EACH TYPE ARE IN THE FOLLOWING? HOPTON

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a) H 2 O2 x H1 x O b) NaOH1 x Na1 x O1 x H c) (NH 4 ) 2 SO 4 2 x N4 x O8 x H1 x S d) Ca(OH) 2 1 x Ca2 x O2 x H e) H 2 SO 4 2 x H4 x O1 x S f) CuSO 4.5H 2 O 1 x Cu10 x H9 x O1 x S RELATIVE FORMULA MASS HOW MANY ATOMS OF EACH TYPE ARE IN THE FOLLOWING? HOPTON

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a) H 2 O2 x H1 x O b) NaOH1 x Na1 x O1 x H c) (NH 4 ) 2 SO 4 2 x N4 x O8 x H1 x S d) Ca(OH) 2 1 x Ca2 x O2 x H e) H 2 SO 4 2 x H4 x O1 x S f) CuSO 4.5H 2 O 1 x Cu10 x H9 x O1 x S A NUMBER IN THE FRONT OF A FORMULA MULTIPLIES EVERYTHING IN THAT FORMULA RELATIVE FORMULA MASS HOW MANY ATOMS OF EACH TYPE ARE IN THE FOLLOWING? HOPTON

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a) H 2 O2 x H1 x O b) NaOH1 x Na1 x O1 x H c) (NH 4 ) 2 SO 4 2 x N4 x O8 x H1 x S d) Ca(OH) 2 1 x Ca2 x O2 x H e) H 2 SO 4 2 x H4 x O1 x S f) CuSO 4.5H 2 O 1 x Cu10 x H9 x O1 x S A NUMBER IN THE FRONT OF A FORMULA MULTIPLIES EVERYTHING IN THAT FORMULA g) 2 NaOH2 x Na2 x O2 x H h) 3 Ca(OH) 2 3 x Ca6 x O6 x H i) 2 Na 2 HPO 4 4 x Na8 x O2 x H2 x P RELATIVE FORMULA MASS HOW MANY ATOMS OF EACH TYPE ARE IN THE FOLLOWING? HOPTON

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a) H 2 O2 x H1 x O b) NaOH1 x Na1 x O1 x H c) (NH 4 ) 2 SO 4 2 x N4 x O8 x H1 x S d) Ca(OH) 2 1 x Ca2 x O2 x H e) H 2 SO 4 2 x H4 x O1 x S f) CuSO 4.5H 2 O 1 x Cu10 x H9 x O1 x S A NUMBER IN THE FRONT OF A FORMULA MULTIPLIES EVERYTHING IN THAT FORMULA g) 2 NaOH2 x Na2 x O2 x H h) 3 Ca(OH) 2 3 x Ca6 x O6 x H i) 2 Na 2 HPO 4 4 x Na8 x O2 x H2 x P RELATIVE FORMULA MASS HOW MANY ATOMS OF EACH TYPE ARE IN THE FOLLOWING?

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RELATIVE FORMULA MASS HOPTON The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula HOPTON

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 O

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18 Copper CuSO 4 sulphate

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18 Copper CuSO 4 Cu+S+ 4 x O sulphate

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18 Copper CuSO 4 Cu+S+ 4 x O sulphate x 16

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18 Copper CuSO 4 Cu+S+ 4 x O sulphate x 16= 160

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18 Copper CuSO 4 Cu+S+ 4 x O sulphate x 16= 160 TAKE CARE WHEN THERE ARE BRACKETS

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18 Copper CuSO 4 Cu+S+ 4 x O sulphate x 16= 160 TAKE CARE WHEN THERE ARE BRACKETS Calcium Ca(OH) 2 hydroxide

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18 Copper CuSO 4 Cu+S+ 4 x O sulphate x 16= 160 TAKE CARE WHEN THERE ARE BRACKETS Calcium Ca(OH) 2 Ca+ 2 lots of OH hydroxide

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18 Copper CuSO 4 Cu+S+ 4 x O sulphate x 16= 160 TAKE CARE WHEN THERE ARE BRACKETS Calcium Ca(OH) 2 Ca+ 2 lots of OH hydroxideCa+ O + H+ O + H

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18 Copper CuSO 4 Cu+S+ 4 x O sulphate x 16= 160 TAKE CARE WHEN THERE ARE BRACKETS Calcium Ca(OH) 2 Ca+ 2 lots of OH hydroxideCa+ O + H+ O + H

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RELATIVE FORMULA MASS HOPTON H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64 The relative formula mass is the sum of the relative atomic masses of ALL the atoms present in the formula Water H 2 OH+ H+O = 18 Copper CuSO 4 Cu+S+ 4 x O sulphate x 16= 160 TAKE CARE WHEN THERE ARE BRACKETS Calcium Ca(OH) 2 Ca+ 2 lots of OH hydroxideCa+ O + H+ O + H = 74

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RELATIVE FORMULA MASS HOPTON Use the list of relative atomic masses to calculate the relative formula mass of the following compounds H 2 O 2 H 2 O NaOHCH 4 C 5 H 12 NaC l H 2 SO 4 Na 2 SO 4 CaC l 2 CaCO 3 NH 4 NO 3 CuSO 4 A l 2 O 3 Ca(OH) 2 A l 2 (SO 4 ) 3 H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu = 64

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RELATIVE FORMULA MASS HOPTON Use the list of relative atomic masses to calculate the relative formula mass of the following compounds H 2 O 2 H 2 O NaOHCH 4 C 5 H 12 NaC l H 2 SO 4 Na 2 SO 4 CaC l 2 CaCO 3 NH 4 NO 3 CuSO 4 A l 2 O 3 Ca(OH) 2 A l 2 (SO 4 ) 3 H = 1; C = 12; N = 14; O = 16; Na = 23; Mg = 24; Al = 27; S = 32; Cl = 35.5; K = 39; Ca = 40; Fe = 56; Cu =

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HOPTON PERCENTAGE COMPOSITION

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HOPTON It can be quite useful to know how much of an element is present in a compound. This is not how many atoms there are BUT what mass is present. This has some relevance when considering how much metal is in a particular ore.

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Metal ores do not just contain a metal, there are other elements present. eg Fe 2 O 3, TiO 2, ZnS. PERCENTAGE COMPOSITION HOPTON

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Metal ores do not just contain a metal, there are other elements present. eg Fe 2 O 3, TiO 2, ZnS. To calculate the PERCENTAGE BY MASS of a metal in an ore; PERCENTAGE COMPOSITION HOPTON

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Metal ores do not just contain a metal, there are other elements present. eg Fe 2 O 3, TiO 2, ZnS. To calculate the PERCENTAGE BY MASS of a metal in an ore; 1 Calculate the formula mass (Fe 2 O 3 ) = 160 PERCENTAGE COMPOSITION HOPTON

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Metal ores do not just contain a metal, there are other elements present. eg Fe 2 O 3, TiO 2, ZnS. To calculate the PERCENTAGE BY MASS of a metal in an ore; 1 Calculate the formula mass (Fe 2 O 3 ) = Calculate how much of this is Fe = 112 PERCENTAGE COMPOSITION HOPTON

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Metal ores do not just contain a metal, there are other elements present. eg Fe 2 O 3, TiO 2, ZnS. To calculate the PERCENTAGE BY MASS of a metal in an ore; 1 Calculate the formula mass (Fe 2 O 3 ) = Calculate how much of this is Fe = Calculate the fraction that is Fe PERCENTAGE COMPOSITION HOPTON

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Metal ores do not just contain a metal, there are other elements present. eg Fe 2 O 3, TiO 2, ZnS. To calculate the PERCENTAGE BY MASS of a metal in an ore; 1 Calculate the formula mass (Fe 2 O 3 ) = Calculate how much of this is Fe = Calculate the fraction that is Fe Calculate the percentage that is Fe112 x 100= 160 PERCENTAGE COMPOSITION HOPTON

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Metal ores do not just contain a metal, there are other elements present. eg Fe 2 O 3, TiO 2, ZnS. To calculate the PERCENTAGE BY MASS of a metal in an ore; 1 Calculate the formula mass (Fe 2 O 3 ) = Calculate how much of this is Fe = Calculate the fraction that is Fe Calculate the percentage that is Fe112 x 100= 70.0% 160 PERCENTAGE COMPOSITION HOPTON

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Metal ores do not just contain a metal, there are other elements present. eg Fe 2 O 3, TiO 2, ZnS. To calculate the PERCENTAGE BY MASS of a metal in an ore; 1 Calculate the formula mass (Fe 2 O 3 ) = Calculate how much of this is Fe = Calculate the fraction that is Fe Calculate the percentage that is Fe112 x 100= 70.0% 160 Calculate the percentage of each metal in…A l 2 O 3 TiO 2 CuFeS 2 ZnSNaC l PERCENTAGE COMPOSITION HOPTON

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REACTING MASSES HOPTON

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The masses of all the atoms at the end of a reaction (THE PRODUCTS) must equal the masses of all the atoms at the start of the reaction (THE REACTANTS). REACTING MASSES HOPTON

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The masses of all the atoms at the end of a reaction (THE PRODUCTS) must equal the masses of all the atoms at the start of the reaction (THE REACTANTS). copper + sulphuric acid copper + water oxide sulphate Write out a word equation. HOPTON REACTING MASSES

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The masses of all the atoms at the end of a reaction (THE PRODUCTS) must equal the masses of all the atoms at the start of the reaction (THE REACTANTS). copper + sulphuric acid copper + water oxide sulphate CuO + H 2 SO 4 CuSO 4 + H 2 O Write out a proper equation showing the correct formulae. HOPTON REACTING MASSES

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The masses of all the atoms at the end of a reaction (THE PRODUCTS) must equal the masses of all the atoms at the start of the reaction (THE REACTANTS). copper + sulphuric acid copper + water oxide sulphate CuO + H 2 SO 4 CuSO 4 + H 2 O (1x1) (4x16) (4x16) (2x1) + 16 Look up the atomic masses in a table and work out the formula mass of each chemical in the equation. HOPTON REACTING MASSES

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The masses of all the atoms at the end of a reaction (THE PRODUCTS) must equal the masses of all the atoms at the start of the reaction (THE REACTANTS). copper + sulphuric acid copper + water oxide sulphate CuO + H 2 SO 4 CuSO 4 + H 2 O (1x1) (4x16) (4x16) (2x1) Look up the atomic masses in a table and work out the formula mass of each chemical in the equation. HOPTON REACTING MASSES

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The masses of all the atoms at the end of a reaction (THE PRODUCTS) must equal the masses of all the atoms at the start of the reaction (THE REACTANTS). copper + sulphuric acid copper + water oxide sulphate CuO + H 2 SO 4 CuSO 4 + H 2 O (1x1) (4x16) (4x16) (2x1) This shows that the masses after the reaction are the same as the masses before. HOPTON REACTING MASSES

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HOPTON YIELD AND PERCENTAGE YIELD

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ( assuming 100% conversion ) HOPTON YIELD AND PERCENTAGE YIELD

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O YIELD AND PERCENTAGE YIELD HOPTON

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O If you start with 80g of copper oxide, you can get a maximum of 160g of copper sulphate. YIELD AND PERCENTAGE YIELD HOPTON

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O If you start with 80g of copper oxide, you can get a maximum of 160g of copper sulphate. Q.What is the maximum yield of copper sulphate if you start with a) 20g of copper oxide b) 400g of copper oxide YIELD AND PERCENTAGE YIELD HOPTON

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O If you start with 80g of copper oxide, you can get a maximum of 160g of copper sulphate. Q.What is the maximum yield of copper sulphate if you start with a) 20g of copper oxideAns.40g b) 400g of copper oxide YIELD AND PERCENTAGE YIELD HOPTON

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O If you start with 80g of copper oxide, you can get a maximum of 160g of copper sulphate. Q.What is the maximum yield of copper sulphate if you start with a) 20g of copper oxideAns.40g b) 400g of copper oxideAns.800g YIELD AND PERCENTAGE YIELD HOPTON

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O Q.If you start with 80g of copper oxide and only get 120g of copper sulphate, what is the percentage yield? YIELD AND PERCENTAGE YIELD HOPTON

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O Q.If you start with 80g of copper oxide and only get 120g of copper sulphate, what is the percentage yield? 80g should give a maximum of 160g. YIELD AND PERCENTAGE YIELD HOPTON

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O Q.If you start with 80g of copper oxide and only get 120g of copper sulphate, what is the percentage yield? 80g should give a maximum of 160g. However only 120g are produced. YIELD AND PERCENTAGE YIELD HOPTON

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O Q.If you start with 80g of copper oxide and only get 120g of copper sulphate, what is the percentage yield? 80g should give a maximum of 160g. However only 120g are produced. The fraction produced is 120/160 = ¾ (0.75). YIELD AND PERCENTAGE YIELD HOPTON

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O Q.If you start with 80g of copper oxide and only get 120g of copper sulphate, what is the percentage yield? 80g should give a maximum of 160g. However only 120g are produced. The fraction produced is 120/160 = ¾ (0.75). Multiply by 100 to get the percentage. YIELD AND PERCENTAGE YIELD HOPTON

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YIELD How much of a chemical you get from a reaction. PERCENTAGEHow much of a chemical you get YIELD COMPARED WITH how much you should get. ExampleCuO + H 2 SO 4 CuSO 4 + H 2 O Q.If you start with 80g of copper oxide and only get 120g of copper sulphate, what is the percentage yield? 80g should give a maximum of 160g. However only 120g are produced. The fraction produced is 120/160 = ¾ (0.75). ANS 75% yield Multiply by 100 to get the percentage. ANS 75% yield YIELD AND PERCENTAGE YIELD HOPTON

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©2011 JONATHAN HOPTON & KNOCKHARDY PUBLISHING CALCULATIONS INVOLVING FORMULAE THE END

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