Changing Mass

In chemical reactions, substances may seem to lose or gain mass. Normally, 1 of the reactants (or products) is a gas, and gas can escape into the surrounding environment.

Burning of wood

When wood is burnt, it releases carbon dioxide and water (and often other gases).
These gases can escape into the atmosphere. These gases can't be weighed easily at the end of a reaction.

Corrosion of metals

The mass of the oxide produced will be larger than the mass of the starting metals because oxygen atoms from the atmosphere have been added:
- E.g. 2Mg + O₂ → 2MgO
The change in mass will equal the mass of the oxygen atoms which have been added.

Zinc + hydrochloric acid

During this reaction, you would expect the mass of the flask and reactants (zinc and hydrochloric acid) to decrease.
This is because the hydrogen gas produced will escape from the flask.

1Atomic Structure

2Chemical Bonding

2.1Chemical Bonds

2.1.1Types of Bonds

2.1.2Ions

2.1.3Ionic Bonds

2.1.4Ionic Compounds

2.1.5Empirical Formulae

2.1.6Covalent Bonds

2.1.7Metallic Bonds

2.1.8Covalent Bond Examples

2.1.9Representing Covalent Bonds

2.1.10Dots-And-Cross Diagrams

2.1.11Dots-And-Cross Diagrams 2

2.1.12Exam-Style Questions - Chemical Bonds

2.2States of Matter

2.2.1States of Matter

2.2.2Simple Sphere

2.2.3Changing State

2.2.4Changing State 2

2.2.5Changing State HyperLearning

2.2.6State Symbols

2.2.7Exam-Style Questions - States of Matter

2.3Chemical Properties

3Quantitative Chemistry

3.1Chemical Measurements

3.1.1Conservation of Mass

3.1.2Relative Formula Mass

3.1.3Calculating Relative Formula Mass

3.1.4Relative Formula Mass - Calculations

3.1.5Changing Mass

3.1.6Measuring Mass

3.1.7Equations

3.1.8Empirical Formula

3.1.9Introducing Moles

3.1.10Relative Formula Mass

3.1.11Amounts of Substance

3.1.12Moles to Balance Equations

3.1.13Limiting Reactants

3.1.14Concentration of Solutions

3.1.15Moles - Calculations

3.1.16Percentage Yield

3.1.17Calculating Yield

3.1.18Percentage Yield - Calculations

3.1.19Moles & Yield

3.1.20Moles & Yield 2

3.1.21Atom Economy

3.1.22Reaction Pathway

3.1.23Atom Economy - Calculations

3.1.24Concentrations of Solute

3.1.25Calculating the Amount of Solute

3.1.26Amount of Substance in Relation to Volumes and Gas

3.1.27Concentrations & Amounts - Calculations

3.1.28Empirical Formula - Calculations

3.1.29End of Topic Test - Quant Chemistry

3.1.30Grade 9 - Quantitative Chemistry

3.1.31Exam-Style Questions - Moles

4Chemical Changes

4.1Acids, Alkalis & Redox Reactions

4.1.1Acids & Alkalis

4.1.2Redox Reactions - Oxidation

4.1.3Redox Reactions - Metal Oxide

4.2Reactivity of Metals

4.2.1Reactivity Diagram

4.2.2Displacement Reactions

4.2.3Displacement Reactions - Halogens

4.2.4Reactions with Water

4.2.5Reactions with Acid

4.2.6Reactivity Tests

4.2.7Reactivity Tests 2

4.2.8Extraction of Metals

4.2.9Exam-Style Questions - Displacement Reactions

4.3Reactions of Acids

4.3.1Reactions of Metals with Acids

4.3.2Redox Reactions

4.3.3Neutralisation of Acids

4.3.4Soluble Salts

4.3.5Required Practical: Separating Mixtures

4.3.6The pH Scale

4.3.7Numerical pH Scale

4.3.8Measuring pH

4.3.9Neutralisation & Titrations

4.3.10Neutralisation & Titrations 2

4.3.11Neutralisation & Titrations 3

4.3.12Neutralisation & Titrations 4

4.3.13Strong and Weak Acids

4.4Electrolysis

4.4.1Electrolysis Process

4.4.2Molten Ionic Compound

4.4.3Metal Extraction

4.4.4Electrolysis of Aqueous Solutions

4.4.5Half Equations

4.4.6End of Topic Test - Chemical Changes

4.4.7Grade 9 - Chemical Changes

4.4.8Exam-Style Questions - Electrolysis

5Energy Changes

5.1Exothermic & Endothermic Reactions

5.1.1Energy Conservation

5.1.2Exothermic Reactions

5.1.3Endothermic Reactions

5.1.4Reaction Profiles Requirements

5.1.5Reaction Profiles

5.1.6Reaction Profiles - Catalysed vs Uncatalysed

5.1.7Reaction Profiles - Chemical Bonds

5.2Chemical Cells & Fuel Cells

5.2.1Chemical Cells

5.2.2Changing Voltage Output

5.2.3Batteries

5.2.4Charging of Cells

5.2.5Fuel Cells

5.2.6Hydrogen Fuel Cell

5.2.7Hydrogen as an Alternative

5.2.8End of Topic Test - Energy Changes

5.2.9Grade 9 - Energy Changes

5.2.10Exam-Style Questions - Fuel Cells

6The Rate & Extent of Chemical Change

6.1Rate of Reaction

6.1.1Chemical Reactions

6.1.2Plotting Reaction Rates

6.1.3Collision Theory

6.1.4Key Factors of Rate of Reaction

6.1.5Catalysts

6.1.6Catalysts in Industry

6.2Reversible Reactions

6.2.1Reversible Reactions

6.2.2Dynamic Equilibrium

6.2.3Conditions and Equilibrium

6.2.4Equilibrium Position - Temperature

6.2.5Equilibrium Position - Pressure

6.2.6Equilibrium Position - Concentration

6.2.7End of Topic Test - Rates of Reaction

6.2.8Grade 9 - Rate & Extent of Chemical Change

6.2.9Exam-Style Questions - Reversible Reactions

7Organic Chemistry

7.1Carbon Compounds

7.1.1Crude Oil

7.1.2Properties of Hydrocarbons

7.1.3Alkanes

7.1.4Smallest Alkanes

7.1.5Fractional Distillation

7.1.6Process of Fractional Distillation

7.1.7Homologous Series

7.1.8Burning Hydrocarbons

7.1.9Heavy Fractions of Crude Oil

7.1.10Cracking

7.1.11Uses of Alkenes

7.1.12Exam-Style Questions - Organic Compounds

7.2Alkenes & Alcohols

8Chemical Analysis

9Chemistry of the Atmosphere

9.1The Earth's Atmosphere

9.1.1Proportions of Gases in the Atmosphere

9.1.2The Earth's Early Atmosphere

9.1.3Oxygen in the Atmosphere

9.1.4Carbon Dioxide in the Atmosphere

9.1.5Greenhouse Gases

9.1.6Greenhouse Gases & Human Activities

9.1.7Greenhouse Gases & Climate

9.1.8Climate Change

9.1.9Carbon Footprints

9.1.10Carbon Footprints Barriers

9.1.11Common Atmospheric Pollutants

9.1.12Properties of Atmospheric Pollutants

9.1.13End of Topic Test - The Earth

9.1.14Grade 9 - Chemistry of the Atmosphere

9.1.15Exam-Style Questions - Earth's Atmosphere

10Using Resources

10.1Using the Earth's Resources

10.1.1Potable Water

10.1.2Potable Water Sources

10.1.3Potable Water in the UK

10.1.4Potable Water in Saudi Arabia

10.1.5Natural Resources

10.1.6Uses of Natural Resources

10.1.7Waste Water

10.1.8Sewage Treatment

10.1.9Metal Ore Extraction

10.1.10Properties of Copper

10.1.11Overexploitation of Extraction Methods

10.1.12Alternative Extraction Methods

10.2Life Cycle Assessments & Recycling

10.2.1Life Cycle Assessments

10.2.2Comparative Life Cycle Assessments

10.2.3Difficulties with LCA

10.2.4Reducing Resource Usage

10.2.5Reducing Use of Glass

10.2.6Reducing Use of Metal

10.2.7Exam-Style Questions - Life Cycle Assessments

10.3Using Materials

10.3.1Corrosion

10.3.2Preventing Corrosion

10.3.3Alloys

10.3.4Ceramics

10.3.5Polymers

10.3.6Composites

10.4The Haber Process & NPK Fertilisers

10.4.1Plants and Nitrogen

10.4.2The Haber Process

10.4.3The Haber Process - Equation

10.4.4The Haber Process - Trade-Offs

10.4.5Importance of Fertilisers

10.4.6Formulated vs Manure Fertilisers

10.4.7NPK Fertilisers - N-containing Compound

10.4.8NPK Fertilisers - P-containing Compound

10.4.9NPK Fertilisers - K-containing Compound

10.4.10Nitrogen, Phosphorus and Potassium

10.4.11End of Topic Test - Resources

10.4.12Grade 9 - Using Resources

10.4.13Exam-Style Questions - The Haber Process

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