Changes

There are now too many [[Lithium atoms ]] [[atom]]s in the products [[product]]s so we need 2 in the reactants[[reactant]]s.| style="height:20px; width:200px; text-align:left;" |

This equation is '''balanced''': : 2Li + F₂ → 2LiF|} '''Aluminium + Chlorine → Aluminium Chloride''': _Al + _Cl₂ → _AlCl₃: Reactants = Products: 1Al = 1Al: 2Cl ≠ 3ClWe need the same number of [[Chlorine]] [[atom]]s on both sides. To do that we can find the Lowest Common Multiple. In this case it is 6, so we times the left 2 [[Chlorine]]s by 3 and the right 3 [[Chlorine]]s by 2. : _Al + 3Cl₂ → 2AlCl₃: Reactants = Products: 1Al ≠ 2Al: 6Cl = 6ClThere are now too many [[Aluminium]] [[atom]]s on the right, so we need to multiply the left [[Aluminium]] by 2. : 2Al + 3Cl₂ → 2AlCl₃: Reactants = Products: 2Al = 2Al: 6Cl = 6ClThis equation is now balanced: '''2Al + 3Cl₂ → 2AlCl₃''' '''Aluminium + Oxygen → Aluminium Oxide''': _Al + _O₂ → _Al₂O₃: Reactants = Products: 1Al ≠ 2Al: 2O ≠ 3OWe need the same number of [[Oxygen]] [[atom]]s on both sides. To do that we can find the Lowest Common Multiple. In this case it is 6, so we times the left 2 [[Oxygen]]s by 3 and the right 3 [[Oxygen]]s by 2. : _Al + 3O₂ → 2Al₂O₃: Reactants = Products: 1Al ≠ 4Al: 6O = 6OThe [[Oxygen]] [[atom]]s are now balanced but the [[Aluminium]] [[atom]]s are not. We need 4 times as many [[Aluminium]] [[atom]]s on the left. : 4Al + 3O₂ → 2Al₂O₃: Reactants = Products: 4Al = 4Al: 6O = 6O This equation is now balanced: '''4Al + 3O₂ → 2Al₂O₃''' ==Key Stage 4=====Meaning===A [[Balanced Symbol Equation]] is a way to show the [[reactant]]s and [[product]]s in a [[Chemical Reaction|chemical reaction]] using the [[Chemical Formula|chemical formulae]] of the [[reactant]]s and [[product]]s. ===About Balanced Symbol Equations===: [[Balanced Symbol Equation]]s show the number of [[molecule]]s of each [[chemical]] and the numbers of each [[atom]] within those [[chemical]]s.: [[Balanced Symbol Equation]]s can be used to find the quantity of each [[chemical]] needed to have a complete [[Chemical Reaction|chemical reaction]]. ===Examples===2H₂(g) + O₂(g) → 2H₂O(l) C₂H₄(g) + Br₂(g) → C₂H₄Br₂(g) C₆H₁₂O₆(s) + 6O₂(g) → 6H₂O(l) + 6CO₂(g) 4Al(s) + 3O₂(g) → 2Al₂O₃(s) ===Calculating the Mass Required for a Complete Reaction==={| class="wikitable"| style="height:20px; width:200px; text-align:center;" |Find the [[mass]] of [[Oxygen]] needed to completely [[oxidise]] all of the [[Magnesium]]: 2Mg + O₂ → 2MgO 48g + x = y | style="height:20px; width:200px; text-align:center;" |Find the [[mass]] of [[Oxygen]] needed for the [[Complete Combustion|complete combustion]] of [[Methane]]. CH₄ + 2O₂ → 2H₂O + CO₂ 32g + x = y | style="height:20px; width:200px; text-align:center;" |Find the [[mass]] of [[Hydrochloric Acid]] needed to completely [[Neutralise (Chemistry)|neutralise]] all of the [[Sodium Hydroxide]]. NaOH + HCl → NaCl + H₂O 20g + x = y + z|-| style="height:20px; width:200px; text-align:center;" |Find the [[Relative Formula Mass]] of the [[reactant]]s. M_r of Mg = 24g M_r of O₂ = 16x2 M_r of O₂ = 32g | style="height:20px; width:200px; text-align:center;" |Find the [[Relative Formula Mass]] of the [[reactant]]s. M_r of CH₄ = 16g M_r of O₂ = 16x2 M_r of O₂ = 32g | style="height:20px; width:200px; text-align:center;" |Find the [[Relative Formula Mass]] of the [[reactant]]s. M_r of NaOH = 40g M_r of HCl = 36.5g |-| style="height:20px; width:200px; text-align:center;" |State the [[ratio]] of [[mole]]s of each [[chemical]] needed. 2 [[mole]]s of Mg are needed for every 1 [[mole]] of O₂ | style="height:20px; width:200px; text-align:center;" |State the [[ratio]] of [[mole]]s of each [[chemical]] needed. 1 [[mole]] of CH₄ is needed for every 2 [[mole]]s of O₂ | style="height:20px; width:200px; text-align:center;" |State the [[ratio]] of [[mole]]s of each [[chemical]] needed. 1 [[mole]] of HCl are needed for every 1 [[mole]] of NaOH |- | style="height:20px; width:200px; text-align:center;" |Find the number of [[mole]]s supplied of the known [[mass]]. No. [[Mole]]s = <math>\frac{Mass}{M_r}</math> No. [[Mole]]s = <math>\frac{48}{24}</math> No. [[Mole]]s = 2 Mole Therefore 1 [[mole]] of O₂ is needed. 1 [[mole]] of O₂ = 32g | style="height:20px; width:200px; text-align:center;" |Find the number of [[mole]]s supplied of the known [[mass]]. No. [[Mole]]s = <math>\frac{Mass}{M_r}</math> No. [[Mole]]s = <math>\frac{32}{16}</math> No. [[Mole]]s = 2 Mole Therefore 4 [[mole]]s of O₂ are needed. 4 [[mole]]s of O₂ = 128g | style="height:20px; width:200px; text-align:center;" |Find the number of [[mole]]s supplied of the known [[mass]]. No. [[Mole]]s = <math>\frac{Mass}{M_r}</math> No. [[Mole]]s = <math>\frac{20}{40}</math> No. [[Mole]]s = 0.5 Mole Therefore 0.5 [[mole]] of HCl is needed. 0.5 [[mole]] of HCl = 18.25g |} ===Limiting Reactants===: A [[Limiting Reactant|limiting reactant]] is a [[reactant]] that is not supplied in a large enough quantity for a complete [[Chemical Reaction|reaction]] with the other [[reactant]]s. 2H₂(g) + O₂(g) → 2H₂O(l) : If there is 4g of [[Hydrogen]] then 32g of [[Oxygen]] is needed for a complete [[Chemical Reaction|reaction]] to occur.: If there is 4g of [[Hydrogen]] but only 31g of [[Oxygen]] then the [[Oxygen]] is a [[Limiting Reactant|limiting reactant]].: If there is 3g of [[Hydrogen]] but only 32g of [[Oxygen]] then the [[Hydrogen]] is a [[Limiting Reactant|limiting reactant]]. {| class="wikitable"|-| style="height:20px; width:250px; text-align:center;" |If there are are 6g of [[Carbon]] and 15g of [[Oxygen]] in the following [[Chemical Reaction|reaction]]:C + O₂ → CO₂Which is the [[Limiting Reactant|limiting reactant]] in this [[Chemical Reaction|reaction]]? | style="height:20px; width:250px; text-align:center;" |If there are are 27g of [[Aluminium]] and 32g of [[Oxygen]] in the following [[Chemical Reaction|reaction]]:4Al + 3O₂ → 2Al₂O₃Which is the [[Limiting Reactant|limiting reactant]] in this [[Chemical Reaction|reaction]]? | style="height:20px; width:250px; text-align:center;" |If there are are 180g of [[Glucose]] and 200g of [[Oxygen]] in the following [[Chemical Reaction|reaction]]:C₆H₁₂O₆ + 6O₂ → 6H₂O + 6CO₂Which is the [[Limiting Reactant|limiting reactant]] in this [[Chemical Reaction|reaction]]? |-| style="height:20px; width:250px; text-align:center;" |Find the [[Relative Formula Mass]] of the [[reactant]]s. M_r of C = 12g M_r of O₂ = 32g | style="height:20px; width:250px; text-align:center;" |Find the [[Relative Formula Mass]] of the [[reactant]]s. M_r of NaOH = 40g M_r of HCl = 36.5g | style="height:20px; width:250px; text-align:center;" |Find the [[Relative Formula Mass]] of the [[reactant]]s. M_r of NaOH = 40g M_r of HCl = 36.5g|-| style="height:20px; width:250px; text-align:center;" |State the [[ratio]] of [[mole]]s of each [[chemical]] needed. 1 [[mole]]s of C is needed for every 1 [[mole]] of O₂ | style="height:20px; width:250px; text-align:center;" |State the [[ratio]] of [[mole]]s of each [[chemical]] needed. 4 [[mole]]s of Al are needed for every 3 [[mole]]s of O₂ | style="height:20px; width:250px; text-align:center;" |State the [[ratio]] of [[mole]]s of each [[chemical]] needed. 1 [[mole]] of C₆H₁₂O₆ is needed for every 6 [[mole]]s of O₂|- | style="height:20px; width:250px; text-align:center;" |Find the number of [[mole]]s supplied of each [[chemical]]. No. [[Mole]]s of C = <math>\frac{Mass}{M_r}</math> No. [[Mole]]s of C = <math>\frac{6}{12}</math> No. [[Mole]]s = 0.5 mol Therefore 0.5 [[mole]]s of O₂ is needed. No. [[Mole]]s of O = <math>\frac{Mass}{M_r}</math> No. [[Mole]]s of O = <math>\frac{15}{32}</math> No. [[Mole]]s = 0.46 mol [[Oxygen]] is the [[Limiting Reactant|limiting reactant]].1 [[mole]] of O₂ = 32g| style="height:20px; width:250px; text-align:center;" |Find the number of [[mole]]s supplied of each [[chemical]]. No. [[Mole]]s of Al = <math>\frac{Mass}{M_r}</math> No. [[Mole]]s of Al = <math>\frac{27}{27}</math> No. [[Mole]]s = 1 mol Therefore 0.75 [[mole]]s of O₂ are needed. No. [[Mole]]s of O = <math>\frac{Mass}{M_r}</math> No. [[Mole]]s of O = <math>\frac{32}{32}</math> No. [[Mole]]s = 1 mol [[Oxygen]] is the [[Limiting Reactant|limiting reactant]]. | style="height:20px; width:250px; text-align:center;" |Find the number of [[mole]]s supplied of each [[chemical]]. No. [[Mole]]s of C₆H₁₂O₆ = <math>\frac{Mass}{M_r}</math> No. [[Mole]]s of C₆H₁₂O₆ = <math>\frac{180}{180}</math> No. [[Mole]]s = 1 mol Therefore 6 [[mole]]s of O₂ are needed. No. [[Mole]]s of O = <math>\frac{Mass}{M_r}</math> No. [[Mole]]s of O = <math>\frac{200}{32}</math> No. [[Mole]]s = 6.25 mol [[Glucose]] is the [[Limiting Reactant|limiting reactant]]. |} ===Balancing Equations===: You may know the [[Chemical Formula|chemical formulae]] of the [[reactant]]s and [[product]]s but not know the number of each [[chemical]] needed. For that you must '''balance the equation'''.: To '''balance and equation''' you need the same number of each type of [[atom]] on the left as you do on the right. {| class="wikitable"|+Magnesium Fluoride + Potassium → Potassium Fluoride + Magnesium|-| style="height:20px; width:200px; text-align:center;" |Step 1| style="height:20px; width:200px; text-align:center;" |Step 2| style="height:20px; width:200px; text-align:center;" |Step 3|-|[[File:MgF2+KStep1.png|center|200px]]|[[File:MgF2+KStep2.png|center|200px]]|[[File:MgF2+KStep3.png|center|200px]]|-| style="height:20px; width:200px; text-align:left;" |: _MgF₂ + _K → _KF + _Mg: Reactants = Products: 1Mg = 1Mg: 2F ≠ 1F: 1K = 1KWe need 2 [[Fluorine]] [[atom]]s in the [[product]]s.| style="height:20px; width:200px; text-align:left;" |: _MgF₂ + _K → 2KF + _Mg: Reactants = Products: 1Mg = 1Mg: 2F = 2F: 1K ≠ 2KThere are now too many [[Potassium]] [[atom]]s in the [[product]]s so we need 2 in the [[reactant]]s.| style="height:20px; width:200px; text-align:left;" |: _MgF₂ + 2K → 2KF + _Mg: Reactants = Products: 1Mg = 1Mg: 2F = 2F: 2K = 2KThis equation is '''balanced''': : MgF₂ + 2K → 2KF + Mg|} ====Balancing Equations with Ions====If the [[Electrical Charge|charge]] on an [[ion]] is known, this information can be used to find the [[Chemical Formula|chemical formula]] of an [[Ionic Compound|ionic compound]] and be used to '''balance''' a '''symbol equation'''.: [[Group 1]] [[Element]]s all form +1 [[ion]]s; Li⁺¹, Na⁺¹, K⁺¹: [[Group 2]] [[Element]]s all form +2 [[ion]]s; Be⁺², Mg⁺², Ca⁺²: [[Group 3]] [[Element]]s all form +3 [[ion]]s; Al⁺³: [[Transition Metal]] [[Element]]s can form different [[ion]]s which are shown by Roman Numerals;  [[Iron]] can form [[Iron|Fe (II)]] which is [[Iron|Fe⁺²]] or [[Iron|Fe (III)]] is [[Iron|Fe⁺³]],[[Manganese]] can form [[Manganese|Mn (II)]] which is [[Manganese|Mn⁺²]] or [[Manganese|Mn (IV)]] which is [[Manganese|Mn⁺⁴]]: [[Group 5]] [[Element]]s all form -3 [[ion]]s; N^-3, P^-3: [[Group 6]] [[Element]]s all form -2 [[ion]]s; O^-2, S^-2: [[Group 7]] [[Element]]s all form -1 [[ion]]s; F^-1, Cl^-1 : Some [[Simple Covalent Molecule|covalent]] [[compound]]s can form [[Negative Ion|negative ions]];  [[Carbonate]] forms -2 [[ion]]s CO<Sub>3</sub>^-2 [[Sulphate]] forms -2 [[ion]]s SO<Sub>4</sub>^-2 [[Nitrate]] forms -1 [[ion]]s NO<Sub>3</sub>^-1 {| class="wikitable"|-| style="height:20px; width:200px; text-align:center;" |[[Group 1]] with [[Group 5]]| style="height:20px; width:200px; text-align:center;" |[[Group 3]] with [[Group 6]]| style="height:20px; width:200px; text-align:center;" |[[Sulphate]]s and [[Carbonate]]s with [[Group 2]]|-| style="height:20px; width:200px; text-align:center;" |Since [[Group 1]] forms +1 [[ion]]s and [[Group 5]] forms -3 [[ion]]s there will be 3 [[Group 1]] [[ion]]s for each [[Group 5]] [[ion]].| style="height:20px; width:200px; text-align:center;" |Since [[Group 3]] forms +3 [[ion]]s and [[Group 6]] forms -2 [[ion]]s there will be 2 [[Group 3]] [[ion]]s for every 3 [[Group 6]] [[ion]]s.| style="height:20px; width:200px; text-align:center;" |[[Sulphate]] [[ion]]s and [[Carbonate]] [[ion]]s both have a [[Electrical Charge|charge]] of -2 while [[Group 2]] [[ion]]s have a [[Electrical Charge|charge]] of +2 so there will be 1 [[Sulphate]] or [[Carbonate]] for every 1 [[Group 2]] [[ion]].|-| style="height:20px; width:200px; text-align:center;" |Examples Li₃N Na₃P| style="height:20px; width:200px; text-align:center;" |Examples B₂S₃ Al₂O₃| style="height:20px; width:200px; text-align:center;" |Examples MgSO₄ CaCO ₃|} ===References=======AQA====:[https://www.amazon.co.uk/gp/product/0198359381/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359381&linkCode=as2&tag=nrjc-21&linkId=47c8d1ae58d8b3a5e2094cd447154558 ''Balanced equations, pages 6-7, 64-67, GCSE Chemistry; Third Edition, Oxford University Press, AQA '']:[https://www.amazon.co.uk/gp/product/1782945571/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945571&linkCode=as2&tag=nrjc-21&linkId=9e29fad914244909903e5e93f8a01d52 ''Balancing equations, pages 15, 44, GCSE Chemistry; The Revision Guide, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Balancing equations, pages 181, 183-4, 250-1, GCSE Combined Science Trilogy 1, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/178294639X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=178294639X&linkCode=as2&tag=nrjc-21&linkId=51599bb45a2bfaf7c1b6a978b2ca2616 ''Balancing equations, pages 32, 33, 112, 113, GCSE Combined Science Trilogy; Chemistry, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1782945962/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945962&linkCode=as2&tag=nrjc-21&linkId=476bb5c8d1dfb5c08ac81b6d4d1c98d8 ''Balancing equations, pages 32, 33, 118, 119, GCSE Chemistry, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1471851346/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851346&linkCode=as2&tag=nrjc-21&linkId=3ac654f4b0da781c49c855a1af4c92ea ''Balancing equations, pages 68, 70, 283-4, GCSE Chemistry, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/1782945598/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945598&linkCode=as2&tag=nrjc-21&linkId=ad276ad49df77ab4b40ab4fd0fe09705 ''Balancing equations, pages 99, 199, GCSE Combined Science; The Revision Guide, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Balancing equations; deduction of balancing numbers, pages 188-9, GCSE Combined Science Trilogy 1, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/1471851346/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851346&linkCode=as2&tag=nrjc-21&linkId=3ac654f4b0da781c49c855a1af4c92ea ''Balancing equations; ionic equations, pages 285-6, GCSE Chemistry, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Balancing equations; molar ratios, pages 185-6, GCSE Combined Science Trilogy 1, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/1471851346/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851346&linkCode=as2&tag=nrjc-21&linkId=3ac654f4b0da781c49c855a1af4c92ea ''Balancing numbers calculations, pages 73-4, GCSE Chemistry, Hodder, AQA '']====Edexcel====:[https://www.amazon.co.uk/gp/product/1292120193/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120193&linkCode=as2&tag=nrjc-21&linkId=572df39392fb4200db8391d98ae6314e ''Balanced equations, page 205, GCSE Combined Science, Pearson Edexcel']:[https://www.amazon.co.uk/gp/product/1292120215/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120215&linkCode=as2&tag=nrjc-21&linkId=8f96ddb76196848bafdb124354e4cf77 ''Balanced equations, page 61, GCSE Chemistry, Pearson, Edexcel']:[https://www.amazon.co.uk/gp/product/1782945725/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945725&linkCode=as2&tag=nrjc-21&linkId=694be7494de75af3349537d34e13f7f0 ''Balanced equations, pages 12, 31, 32, GCSE Chemistry; The Revision Guide, CGP, Edexcel']:[https://www.amazon.co.uk/gp/product/1782948147/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782948147&linkCode=as2&tag=nrjc-21&linkId=f63dcd8345f4e49c717b39a228a36c7c ''Balancing equations, pages 23-26, 89, 90, GCSE Chemistry, CGP, Edexcel '']:[https://www.amazon.co.uk/gp/product/0198359381/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359381&linkCode=as2&tag=nrjc-21&linkId=47c8d1ae58d8b3a5e2094cd447154558 ''Symbol equations, page 6, GCSE Chemistry; Third Edition, Oxford University Press, AQA '']:[https://www.amazon.co.uk/gp/product/1782945962/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945962&linkCode=as2&tag=nrjc-21&linkId=476bb5c8d1dfb5c08ac81b6d4d1c98d8 ''Symbol equations, pages 31-33, GCSE Chemistry, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/178294639X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=178294639X&linkCode=as2&tag=nrjc-21&linkId=51599bb45a2bfaf7c1b6a978b2ca2616 ''Symbol equations, pages 31-33, GCSE Combined Science Trilogy; Chemistry, CGP, AQA '']