3.1.7
Equations
Test your knowledge with free interactive questions on Seneca — used by over 10 million students.
Balancing Chemical Equations
Chemical equations must be balanced to make sure that there are the same number of atoms of each element before and after a reaction. The reaction of hydrogen with oxygen to make water will be used as an example of how to do this:
Unbalanced equation
- The unbalanced symbol equation for this reaction is:
- H2 + O2 → H2O
- The equation is unbalanced because there are 2 atoms of oxygen on the left hand side of the equation, but only 1 on the right hand side.
Still unbalanced equation
- We can increase the number of oxygen atoms on the right hand side by adding an H2O molecule:
- H2 + O2 → 2H2O
- However, the equation is still unbalanced as there are now more hydrogen atoms on the right hand side than on the left hand side.
Balanced equation
- The final step is to add an H2 molecule to the left hand side:
- 2H2 + O2 → 2H2O
- Our equation is now balanced.
1Atomic Structure
1.1Atoms & Elements
1.1.1Elements & Compounds1.1.2Chemical Formula1.1.3Chemical Reactions1.1.4Chemical Equations1.1.5Mixtures1.1.6Separating Mixtures1.1.7Separating Mixtures 21.1.8Model of the Atom1.1.9Sub-Atomic Particles1.1.10Atom Size1.1.11Atomic Number1.1.12Atomic Number - Calculations1.1.13Isotopes1.1.14Isotopes HyperLearning1.1.15Isotopes - Calculations1.1.16Relative Atomic Mass1.1.17Electron Structure1.1.18Periodic Table1.1.19The History of the Periodic Table1.1.20Metals & Non-Metals1.1.21Noble Gases1.1.22Displacement Reaction1.1.23Halogens1.1.24Alkali Metals1.1.25Alkali Metals - Properties1.1.26Transition Metals1.1.27Transition Metals - Special Properties1.1.28End of Topic Test - Atomic Structure1.1.29Grade 9 - Atoms & Elements1.1.30Exam-Style Questions - Atomic Structure1.1.31Application Questions - Atomic Structure1.1.32Diagnostic Misconceptions - Balancing Equations1.1.33Diagnostic Misconceptions - Isotopes
2Chemical Bonding
2.1Chemical Bonds
2.2States of Matter
2.3Chemical Properties
2.3.1Ionic Compounds2.3.2Chemical Properties of Ionic Compounds2.3.3Small Molecules2.3.4Chemical Properties of Small Molecules2.3.5Molecular Forces - Polymers2.3.6Molecular Forces - Polypropene2.3.7Giant Covalent Structures2.3.8Metals2.3.9Alloys2.3.10Conductors2.3.11Carbon Structures - Diamond2.3.12Carbon Structures - Graphite2.3.13Carbon Structures - Graphene2.3.14Carbon Structures - Fullerenes2.3.15Carbon Structures - Summary2.3.16Clumps2.3.17Nanoparticles2.3.18Nanotechnology2.3.19Nanotechnology 22.3.20Surface Area to Volume Ratio2.3.21Nanotechnology Uses2.3.22End of Topic Test - Chemical Bonding2.3.23Grade 9 - Bonding & Structure2.3.24Exam-Style Questions - Allotropes of Carbon2.3.25Diagnostic Misconceptions - Conducting Electricity2.3.26Diagnostic Misconceptions - Small Molecules2.3.27Diagnostic Misconceptions - Drawing Polymers
3Quantitative Chemistry
3.1Chemical Measurements
3.1.1Conservation of Mass3.1.2Relative Formula Mass3.1.3Calculating Relative Formula Mass3.1.4Relative Formula Mass - Calculations3.1.5Changing Mass3.1.6Measuring Mass3.1.7Equations3.1.8Empirical Formula3.1.9Introducing Moles3.1.10Relative Formula Mass3.1.11Amounts of Substance3.1.12Moles to Balance Equations3.1.13Limiting Reactants3.1.14Concentration of Solutions3.1.15Moles - Calculations3.1.16Percentage Yield3.1.17Calculating Yield3.1.18Percentage Yield - Calculations3.1.19Moles & Yield3.1.20Moles & Yield 23.1.21Atom Economy3.1.22Reaction Pathway3.1.23Atom Economy - Calculations3.1.24Concentrations of Solute3.1.25Calculating the Amount of Solute3.1.26Amount of Substance in Relation to Volumes and Gas3.1.27Concentrations & Amounts - Calculations3.1.28Empirical Formula - Calculations3.1.29End of Topic Test - Quant Chemistry3.1.30Grade 9 - Quantitative Chemistry3.1.31Exam-Style Questions - Moles3.1.32Diagnostic Misconceptions - Calculating RFM3.1.33Diagnostic Misconceptions - Moles
4Chemical Changes
4.1Acids, Alkalis & Redox Reactions
4.2Reactivity of Metals
4.3Reactions of Acids
4.3.1Reactions of Metals with Acids4.3.2Redox Reactions4.3.3Neutralisation of Acids4.3.4Soluble Salts4.3.5Required Practical: Separating Mixtures4.3.6The pH Scale4.3.7Numerical pH Scale4.3.8Measuring pH4.3.9Neutralisation & Titrations4.3.10Neutralisation & Titrations 24.3.11Neutralisation & Titrations 34.3.12Neutralisation & Titrations 44.3.13Strong and Weak Acids4.3.14Required Practical: Titration
5Energy Changes
5.1Exothermic & Endothermic Reactions
5.1.1Energy Conservation5.1.2Exothermic Reactions5.1.3Endothermic Reactions5.1.4Required Practical: Temperature Changes5.1.5Reaction Profiles Requirements5.1.6Reaction Profiles5.1.7Reaction Profiles - Catalysed vs Uncatalysed5.1.8Reaction Profiles - Chemical Bonds5.1.9Diagnostic Misconceptions - Source of Energy
6The Rate & Extent of Chemical Change
6.1Rate of Reaction
6.2Reversible Reactions
6.2.1Reversible Reactions6.2.2Dynamic Equilibrium6.2.3Conditions and Equilibrium6.2.4Equilibrium Position - Temperature6.2.5Equilibrium Position - Pressure6.2.6Equilibrium Position - Concentration6.2.7End of Topic Test - Rates of Reaction6.2.8Grade 9 - Rate & Extent of Chemical Change6.2.9Exam-Style Questions - Reversible Reactions6.2.10Diagnostic Misconceptions - Temperature6.2.11Diagnostic Misconceptions - Pressure6.2.12Diagnostic Misconceptions - Concentration6.2.13Diagnostic Misconceptions - Catalysts
7Organic Chemistry
7.1Carbon Compounds
7.1.1Crude Oil7.1.2Properties of Hydrocarbons7.1.3Alkanes7.1.4Smallest Alkanes7.1.5Fractional Distillation7.1.6Process of Fractional Distillation7.1.7Homologous Series7.1.8Burning Hydrocarbons7.1.9Heavy Fractions of Crude Oil7.1.10Cracking7.1.11Uses of Alkenes7.1.12Exam-Style Questions - Organic Compounds
7.2Alkenes & Alcohols
7.2.1Structure of Alkenes7.2.2The Shortest Alkenes7.2.3Reactions of Alkenes7.2.4Types of Alkene Reactions7.2.5Alcohols7.2.6The Smallest Alcohols7.2.7Reactions of Alcohols7.2.8Fermentation7.2.9Carboxylic Acids7.2.10The Smallest Carboxylic Acids7.2.11Reactions of Carboxylic Acids7.2.12Addition Polymers7.2.13Addition Polymers Examples7.2.14Condensation Polymers7.2.15Amino Acids7.2.16Naturally Occurring Polymers - Protein (Formation)7.2.17Naturally Occurring Polymers - Protein (Roles)7.2.18Naturally Occurring Polymers - DNA7.2.19Naturally Occurring Polymers - Others7.2.20End of Topic Test - Alkanes & Alkenes7.2.21End of Topic Test - Alcohols, Acids & Polymers7.2.22Grade 9 - Organic Chemistry7.2.23Exam-Style Questions - Alcohols
8Chemical Analysis
8.1Purity, Formulations & Chromatography
8.2Identification of Common Gases
8.3Identifying Ions
8.3.1Flame Tests8.3.2Required Practical: Flame Tests8.3.3Metal Hydroxides8.3.4Metal Hydroxides 28.3.5Carbonates8.3.6Halides8.3.7Sulfates8.3.8Methodology for Chemical Analysis8.3.9Methodology for Chemical Analysis 28.3.10Flame Emission Spectroscopy8.3.11Flame Emission Spectroscopy Analysis8.3.12End of Topic Test - Chemical Analysis8.3.13Grade 9 - Chemical Analysis8.3.14Exam-Style Questions - Identification of ions
9Chemistry of the Atmosphere
9.1The Earth's Atmosphere
9.1.1Proportions of Gases in the Atmosphere9.1.2The Earth's Early Atmosphere9.1.3Oxygen in the Atmosphere9.1.4Carbon Dioxide in the Atmosphere9.1.5Greenhouse Gases9.1.6Greenhouse Gases & Human Activities9.1.7Greenhouse Gases & Climate9.1.8Climate Change9.1.9Carbon Footprints9.1.10Carbon Footprints Barriers9.1.11Common Atmospheric Pollutants9.1.12Properties of Atmospheric Pollutants9.1.13End of Topic Test - The Earth9.1.14Grade 9 - Chemistry of the Atmosphere9.1.15Exam-Style Questions - Earth's Atmosphere9.1.16Diagnostic Misconceptions - Greenhouse Effect
10Using Resources
10.1Using the Earth's Resources
10.1.1Potable Water10.1.2Potable Water Sources10.1.3Potable Water in the UK10.1.4Potable Water in Saudi Arabia10.1.5Required Practical: Analysing and Purifying Water10.1.6Natural Resources10.1.7Uses of Natural Resources10.1.8Waste Water10.1.9Sewage Treatment10.1.10Metal Ore Extraction10.1.11Properties of Copper10.1.12Overexploitation of Extraction Methods10.1.13Alternative Extraction Methods
10.2Life Cycle Assessments & Recycling
10.3Using Materials
10.4The Haber Process & NPK Fertilisers
10.4.1Plants and Nitrogen10.4.2The Haber Process10.4.3The Haber Process - Equation10.4.4The Haber Process - Trade-Offs10.4.5Importance of Fertilisers10.4.6Formulated vs Manure Fertilisers10.4.7NPK Fertilisers - N-containing Compound10.4.8NPK Fertilisers - P-containing Compound10.4.9NPK Fertilisers - K-containing Compound10.4.10Nitrogen, Phosphorus and Potassium10.4.11End of Topic Test - Resources10.4.12Grade 9 - Using Resources10.4.13Exam-Style Questions - The Haber Process
Jump to other topics
1Atomic Structure
1.1Atoms & Elements
1.1.1Elements & Compounds1.1.2Chemical Formula1.1.3Chemical Reactions1.1.4Chemical Equations1.1.5Mixtures1.1.6Separating Mixtures1.1.7Separating Mixtures 21.1.8Model of the Atom1.1.9Sub-Atomic Particles1.1.10Atom Size1.1.11Atomic Number1.1.12Atomic Number - Calculations1.1.13Isotopes1.1.14Isotopes HyperLearning1.1.15Isotopes - Calculations1.1.16Relative Atomic Mass1.1.17Electron Structure1.1.18Periodic Table1.1.19The History of the Periodic Table1.1.20Metals & Non-Metals1.1.21Noble Gases1.1.22Displacement Reaction1.1.23Halogens1.1.24Alkali Metals1.1.25Alkali Metals - Properties1.1.26Transition Metals1.1.27Transition Metals - Special Properties1.1.28End of Topic Test - Atomic Structure1.1.29Grade 9 - Atoms & Elements1.1.30Exam-Style Questions - Atomic Structure1.1.31Application Questions - Atomic Structure1.1.32Diagnostic Misconceptions - Balancing Equations1.1.33Diagnostic Misconceptions - Isotopes
2Chemical Bonding
2.1Chemical Bonds
2.2States of Matter
2.3Chemical Properties
2.3.1Ionic Compounds2.3.2Chemical Properties of Ionic Compounds2.3.3Small Molecules2.3.4Chemical Properties of Small Molecules2.3.5Molecular Forces - Polymers2.3.6Molecular Forces - Polypropene2.3.7Giant Covalent Structures2.3.8Metals2.3.9Alloys2.3.10Conductors2.3.11Carbon Structures - Diamond2.3.12Carbon Structures - Graphite2.3.13Carbon Structures - Graphene2.3.14Carbon Structures - Fullerenes2.3.15Carbon Structures - Summary2.3.16Clumps2.3.17Nanoparticles2.3.18Nanotechnology2.3.19Nanotechnology 22.3.20Surface Area to Volume Ratio2.3.21Nanotechnology Uses2.3.22End of Topic Test - Chemical Bonding2.3.23Grade 9 - Bonding & Structure2.3.24Exam-Style Questions - Allotropes of Carbon2.3.25Diagnostic Misconceptions - Conducting Electricity2.3.26Diagnostic Misconceptions - Small Molecules2.3.27Diagnostic Misconceptions - Drawing Polymers
3Quantitative Chemistry
3.1Chemical Measurements
3.1.1Conservation of Mass3.1.2Relative Formula Mass3.1.3Calculating Relative Formula Mass3.1.4Relative Formula Mass - Calculations3.1.5Changing Mass3.1.6Measuring Mass3.1.7Equations3.1.8Empirical Formula3.1.9Introducing Moles3.1.10Relative Formula Mass3.1.11Amounts of Substance3.1.12Moles to Balance Equations3.1.13Limiting Reactants3.1.14Concentration of Solutions3.1.15Moles - Calculations3.1.16Percentage Yield3.1.17Calculating Yield3.1.18Percentage Yield - Calculations3.1.19Moles & Yield3.1.20Moles & Yield 23.1.21Atom Economy3.1.22Reaction Pathway3.1.23Atom Economy - Calculations3.1.24Concentrations of Solute3.1.25Calculating the Amount of Solute3.1.26Amount of Substance in Relation to Volumes and Gas3.1.27Concentrations & Amounts - Calculations3.1.28Empirical Formula - Calculations3.1.29End of Topic Test - Quant Chemistry3.1.30Grade 9 - Quantitative Chemistry3.1.31Exam-Style Questions - Moles3.1.32Diagnostic Misconceptions - Calculating RFM3.1.33Diagnostic Misconceptions - Moles
4Chemical Changes
4.1Acids, Alkalis & Redox Reactions
4.2Reactivity of Metals
4.3Reactions of Acids
4.3.1Reactions of Metals with Acids4.3.2Redox Reactions4.3.3Neutralisation of Acids4.3.4Soluble Salts4.3.5Required Practical: Separating Mixtures4.3.6The pH Scale4.3.7Numerical pH Scale4.3.8Measuring pH4.3.9Neutralisation & Titrations4.3.10Neutralisation & Titrations 24.3.11Neutralisation & Titrations 34.3.12Neutralisation & Titrations 44.3.13Strong and Weak Acids4.3.14Required Practical: Titration
5Energy Changes
5.1Exothermic & Endothermic Reactions
5.1.1Energy Conservation5.1.2Exothermic Reactions5.1.3Endothermic Reactions5.1.4Required Practical: Temperature Changes5.1.5Reaction Profiles Requirements5.1.6Reaction Profiles5.1.7Reaction Profiles - Catalysed vs Uncatalysed5.1.8Reaction Profiles - Chemical Bonds5.1.9Diagnostic Misconceptions - Source of Energy
6The Rate & Extent of Chemical Change
6.1Rate of Reaction
6.2Reversible Reactions
6.2.1Reversible Reactions6.2.2Dynamic Equilibrium6.2.3Conditions and Equilibrium6.2.4Equilibrium Position - Temperature6.2.5Equilibrium Position - Pressure6.2.6Equilibrium Position - Concentration6.2.7End of Topic Test - Rates of Reaction6.2.8Grade 9 - Rate & Extent of Chemical Change6.2.9Exam-Style Questions - Reversible Reactions6.2.10Diagnostic Misconceptions - Temperature6.2.11Diagnostic Misconceptions - Pressure6.2.12Diagnostic Misconceptions - Concentration6.2.13Diagnostic Misconceptions - Catalysts
7Organic Chemistry
7.1Carbon Compounds
7.1.1Crude Oil7.1.2Properties of Hydrocarbons7.1.3Alkanes7.1.4Smallest Alkanes7.1.5Fractional Distillation7.1.6Process of Fractional Distillation7.1.7Homologous Series7.1.8Burning Hydrocarbons7.1.9Heavy Fractions of Crude Oil7.1.10Cracking7.1.11Uses of Alkenes7.1.12Exam-Style Questions - Organic Compounds
7.2Alkenes & Alcohols
7.2.1Structure of Alkenes7.2.2The Shortest Alkenes7.2.3Reactions of Alkenes7.2.4Types of Alkene Reactions7.2.5Alcohols7.2.6The Smallest Alcohols7.2.7Reactions of Alcohols7.2.8Fermentation7.2.9Carboxylic Acids7.2.10The Smallest Carboxylic Acids7.2.11Reactions of Carboxylic Acids7.2.12Addition Polymers7.2.13Addition Polymers Examples7.2.14Condensation Polymers7.2.15Amino Acids7.2.16Naturally Occurring Polymers - Protein (Formation)7.2.17Naturally Occurring Polymers - Protein (Roles)7.2.18Naturally Occurring Polymers - DNA7.2.19Naturally Occurring Polymers - Others7.2.20End of Topic Test - Alkanes & Alkenes7.2.21End of Topic Test - Alcohols, Acids & Polymers7.2.22Grade 9 - Organic Chemistry7.2.23Exam-Style Questions - Alcohols
8Chemical Analysis
8.1Purity, Formulations & Chromatography
8.2Identification of Common Gases
8.3Identifying Ions
8.3.1Flame Tests8.3.2Required Practical: Flame Tests8.3.3Metal Hydroxides8.3.4Metal Hydroxides 28.3.5Carbonates8.3.6Halides8.3.7Sulfates8.3.8Methodology for Chemical Analysis8.3.9Methodology for Chemical Analysis 28.3.10Flame Emission Spectroscopy8.3.11Flame Emission Spectroscopy Analysis8.3.12End of Topic Test - Chemical Analysis8.3.13Grade 9 - Chemical Analysis8.3.14Exam-Style Questions - Identification of ions
9Chemistry of the Atmosphere
9.1The Earth's Atmosphere
9.1.1Proportions of Gases in the Atmosphere9.1.2The Earth's Early Atmosphere9.1.3Oxygen in the Atmosphere9.1.4Carbon Dioxide in the Atmosphere9.1.5Greenhouse Gases9.1.6Greenhouse Gases & Human Activities9.1.7Greenhouse Gases & Climate9.1.8Climate Change9.1.9Carbon Footprints9.1.10Carbon Footprints Barriers9.1.11Common Atmospheric Pollutants9.1.12Properties of Atmospheric Pollutants9.1.13End of Topic Test - The Earth9.1.14Grade 9 - Chemistry of the Atmosphere9.1.15Exam-Style Questions - Earth's Atmosphere9.1.16Diagnostic Misconceptions - Greenhouse Effect
10Using Resources
10.1Using the Earth's Resources
10.1.1Potable Water10.1.2Potable Water Sources10.1.3Potable Water in the UK10.1.4Potable Water in Saudi Arabia10.1.5Required Practical: Analysing and Purifying Water10.1.6Natural Resources10.1.7Uses of Natural Resources10.1.8Waste Water10.1.9Sewage Treatment10.1.10Metal Ore Extraction10.1.11Properties of Copper10.1.12Overexploitation of Extraction Methods10.1.13Alternative Extraction Methods
10.2Life Cycle Assessments & Recycling
10.3Using Materials
10.4The Haber Process & NPK Fertilisers
10.4.1Plants and Nitrogen10.4.2The Haber Process10.4.3The Haber Process - Equation10.4.4The Haber Process - Trade-Offs10.4.5Importance of Fertilisers10.4.6Formulated vs Manure Fertilisers10.4.7NPK Fertilisers - N-containing Compound10.4.8NPK Fertilisers - P-containing Compound10.4.9NPK Fertilisers - K-containing Compound10.4.10Nitrogen, Phosphorus and Potassium10.4.11End of Topic Test - Resources10.4.12Grade 9 - Using Resources10.4.13Exam-Style Questions - The Haber Process
Practice questions on Equations
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- 1
- 2Which of the following equations are balanced?True / false
- 3What is the purpose of balancing a chemical equation?Multiple choice
- 4
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