Required Practical: Effect of Concentration

Effect of Concentration on the Rate of Reaction (Gas Volume Method)

This experiment aims to investigate how altering the concentration of a solution influences the rate at which a gas is produced during a chemical reaction.

Apparatus and materials

Magnesium ribbon (cut into equal lengths)
Sulfuric acid solutions of different concentrations (e.g. 1.0 mol/dm³ and 1.5 mol/dm³)
100 cm³ conical flask
Gas syringe with delivery tube
Rubber bung
Stop clock
Measuring cylinder
Safety goggles and a lab coat

Variables

Independent variable:
- Concentration of the acid
Dependent variable:
- Volume of gas produced over time
Control variables:
- Length and surface area of magnesium ribbon
- Volume of acid used
- Temperature
- Use of the same equipment setup for all trials

Method

Set up the apparatus.
Measure a fixed volume of dilute sulfuric acid and pour it into the conical flask.
Add one strip of magnesium ribbon to the acid and quickly seal the flask with the bung.
Start the stop clock as soon as the magnesium is added.
Record the volume of hydrogen gas collected in the syringe every 10 seconds until no more gas is produced.
Repeat the procedure using a different concentration of acid.

Analysis

Record time (s) and gas volume (cm³) in a results table.
Plot a graph of gas volume against time for each acid concentration.
Compare the gradients (slopes):
- The steeper the line, the faster the rate of reaction.
To calculate the mean rate of reaction =

$\dfrac{Total Mass Of Gas Produced (cm^3)}{Reaction Time (s)}$

Expected Results

Higher acid concentrations will produce hydrogen gas more quickly.
The same total volume of gas may be produced, but in less time.
- This supports the hypothesis that a higher concentration increases the rate of reaction.

Hazards and precautions

Dilute sulfuric acid:
- Acid may irritate the skin and eyes
- Wear goggles and rinse immediately if contact occurs
Reaction mixture fizzing:
- May cause acid spray or foam to escape
- Use a conical flask and avoid leaning over the mixture
Hydrogen gas:
- Flammable if exposed to sparks or flame
- Ensure there are no open flames nearby

Investigating the Rate of Reaction (Colour Change Method)

There are many ways to carry out this practical. This experiment investigates how temperature affects the rate of a chemical reaction by observing the rate at which a solution changes colour.

Apparatus and materials

Measuring cylinders
Conical flask
Stop clock
Sheet of white paper with a black cross drawn on it
Bunsen burner or hot water bath (to adjust temperature)
Thermometer
Solution of choice
Dilute acid of choice

Variables

Independent variable:
- Temperature of the sodium thiosulfate solution
Dependent variable:
- Time taken for the cross to become invisible
Control variables:
- Concentration and volume of both solutions
- The same black cross and viewing method
- Same observer for consistency

Method

This reaction uses sodium thiosulfate and hydrochloric acid.
Pour 50 cm³ of sodium thiosulfate solution into a conical flask.
Place the flask on top of a piece of white paper with a black cross drawn in the centre.
Measure 10 cm³ of dilute hydrochloric acid in a separate cylinder.
Add the acid to the flask, swirl, and start the clock.

Method (continuation)

Observe the solution and note the time when the cross can no longer be seen.
Record the temperature of the reaction mixture.
Repeat the experiment at different starting temperatures:
- 20°C, 30°C, 40°C, 50°C

Analysis

Calculate 1000 ÷ time (s) for each temperature to estimate the reaction rate.
Plot a graph of:
- Rate of reaction (1/s) on the y-axis
- Temperature (°C) on the x-axis
Draw a smooth curve of best fit.
The line should show that higher temperatures lead to faster reactions due to more energetic particle collisions.

Explanation

When temperature increases, particles move more quickly and collide more often with enough energy to react.
- This means the reaction occurs faster, and the sulfur precipitate forms in a shorter time.

1Atomic Structure

1.1Atoms & Elements

1.1.1Elements & Compounds

1.1.2Chemical Formula

1.1.3Chemical Reactions

1.1.4Chemical Equations

1.1.5Mixtures

1.1.6Separating Mixtures

1.1.7Separating Mixtures 2

1.1.8Model of the Atom

1.1.9Sub-Atomic Particles

1.1.10Atom Size

1.1.11Atomic Number

1.1.12Atomic Number - Calculations

1.1.13Isotopes

1.1.14Isotopes HyperLearning

1.1.15Isotopes - Calculations

1.1.16Relative Atomic Mass

1.1.17Electron Structure

1.1.18Periodic Table

1.1.19The History of the Periodic Table

1.1.20Metals & Non-Metals

1.1.21Noble Gases

1.1.22Displacement Reaction

1.1.23Halogens

1.1.24Alkali Metals

1.1.25Alkali Metals - Properties

1.1.26Transition Metals

1.1.27Transition Metals - Special Properties

1.1.28End of Topic Test - Atomic Structure

1.1.29Grade 9 - Atoms & Elements

1.1.30Exam-Style Questions - Atomic Structure

1.1.31Application Questions - Atomic Structure

1.1.32Diagnostic Misconceptions - Balancing Equations

1.1.33Diagnostic Misconceptions - Isotopes

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

2.2.8Diagnostic Misconceptions - Particles

2.3Chemical Properties

2.3.1Ionic Compounds

2.3.2Chemical Properties of Ionic Compounds

2.3.3Small Molecules

2.3.4Chemical Properties of Small Molecules

2.3.5Molecular Forces - Polymers

2.3.6Molecular Forces - Polypropene

2.3.7Giant Covalent Structures

2.3.8Metals

2.3.9Alloys

2.3.10Conductors

2.3.11Carbon Structures - Diamond

2.3.12Carbon Structures - Graphite

2.3.13Carbon Structures - Graphene

2.3.14Carbon Structures - Fullerenes

2.3.15Carbon Structures - Summary

2.3.16Clumps

2.3.17Nanoparticles

2.3.18Nanotechnology

2.3.19Nanotechnology 2

2.3.20Surface Area to Volume Ratio

2.3.21Nanotechnology Uses

2.3.22End of Topic Test - Chemical Bonding

2.3.23Grade 9 - Bonding & Structure

2.3.24Exam-Style Questions - Allotropes of Carbon

2.3.25Diagnostic Misconceptions - Conducting Electricity

2.3.26Diagnostic Misconceptions - Small Molecules

2.3.27Diagnostic Misconceptions - Drawing Polymers

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

3.1.32Diagnostic Misconceptions - Calculating RFM

3.1.33Diagnostic Misconceptions - 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

4.3.14Required Practical: Titration

4.4Electrolysis

4.4.1Electrolysis Process

4.4.2Molten Ionic Compound

4.4.3Metal Extraction

4.4.4Electrolysis of Aqueous Solutions

4.4.5Required Practical: Electrolysis

4.4.6Half Equations

4.4.7End of Topic Test - Chemical Changes

4.4.8Grade 9 - Chemical Changes

4.4.9Exam-Style Questions - Electrolysis

5Energy Changes

5.1Exothermic & Endothermic Reactions

5.1.1Energy Conservation

5.1.2Exothermic Reactions

5.1.3Endothermic Reactions

5.1.4Required Practical: Temperature Changes

5.1.5Reaction Profiles Requirements

5.1.6Reaction Profiles

5.1.7Reaction Profiles - Catalysed vs Uncatalysed

5.1.8Reaction Profiles - Chemical Bonds

5.1.9Diagnostic Misconceptions - Source of Energy

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

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

9.1.16Diagnostic Misconceptions - Greenhouse Effect

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

10.1.5Required Practical: Analysing and Purifying Water

10.1.6Natural Resources

10.1.7Uses of Natural Resources

10.1.8Waste Water

10.1.9Sewage Treatment

10.1.10Metal Ore Extraction

10.1.11Properties of Copper

10.1.12Overexploitation of Extraction Methods

10.1.13Alternative 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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