Home

Science

Acids and alkalis

The pH scale and indicators

The pH scale and indicators

Videos

Summary

Exercises

Select Lesson

Magnetism

Types of magnets and magnetic fields

Electromagnets and solenoids

Space physics

Gravitational forces

Galaxies, stars and light years

Day, night and the four seasons

Matter

Physical changes of matter

Movement of particles: Brownian motion and diffusion

Electricity

Electrical circuits

Measuring current and potential difference

Resistance and Ohm's Law

Series and parallel circuits

Static electricity

Waves

Water waves and superposition

Sound waves

Hearing: the human ear and auditory ranges

The uses of sound waves

How light travels

Light transmission and ray diagrams

Detecting light: cameras and the human eye

Light frequencies, prisms and colour

Forces and motion

Motion and speed

Relative motion

Contact and non-contact forces

How friction affects movement

Force diagrams and resultant forces

Air and water resistance

Moments

Forces and elasticity: Hooke's Law

Pressure

Energy

Energy stores and transfers

Mechanical energy and work done

Energy transfer by heating

Energy calculations

Renewable and non-renewable energy

Energy in the home

Earth and atmosphere

The Earth: structure and properties

The rock cycle and weathering

Types of rock: Sedimentary, metamorphic and igneous

The carbon cycle

The atmosphere and carbon dioxide

Recycling and limited resources

Acids and alkalis

The pH scale and indicators

Neutralisation reactions

Reactions of acids with metals

Reactions of acids with oxides

Chemical reactions

An introduction to chemical reactions

Word and symbol equations

Combustion, oxidation and thermal decomposition

Displacement reactions

Exothermic and endothermic reactions and catalysts

Pure and impure substances

Pure substances and mixtures

Dissolving a mixture

Separating mixtures

Fractional distillation

The periodic table and properties of materials

The modern periodic table

Mendeleev's periodic table

Physical and chemical properties

Predicting reactivity using the periodic table

The properties of metals

The properties of non-metals

Ceramics, polymers and composites

The reactivity series and metal extraction

Atoms, elements and compounds

Dalton's atomic model

Atoms, elements and compounds

Naming chemical compounds

States of matter

Properties of the three states of matter

The particle model of matter

Gas pressure

Changes of state and conservation of mass

Heating and cooling curves

Genetics and evolution

DNA structure, discovery and inheritance

Types and sources of variation

The process of natural selection

Extinction and species preservation

Interactions and interdependencies

Ecosystems and interdependence

Food chains and poison

Food webs and interdependence

Plants

Photosynthesis and plant adaptations

Flower structure and pollination

Fertilisation, seed formation and dispersal

Investigating seed dispersal

Human reproduction

Human reproductive systems

The menstrual cycle

Human reproduction and gestation

Pregnancy and health

Human gas exchange systems

Structure and function of the human gas exchange system

The mechanism of breathing

Impact of exercise, asthma and smoking on gas exchange

Human nutrition, digestion and health

A healthy human diet

Energy requirements and diet imbalances

The structure of the human digestive system

Digestion and the importance of bacteria

The impact of recreational drugs on health

Human skeleton and muscles

The human skeletal system

Muscle function and antagonistic muscle pairs

Measuring the force exerted by muscles

Cells and respiration

How to observe cells under a microscope

Animal cells, plant cells, and unicellular organisms

Cell organisation and diffusion

Aerobic and anaerobic respiration

Explainer Video

Tutor: Alexander

Summary

The pH scale and indicators

In a nutshell

The pH scale shows whether a solution is acidic or alkaline and the degree of acidity and alkalinity. An indicator is something that changes colour based on the solution's pH. 



The pH scale​​

  • The pH scale ranges from 000​ to 141414​​
  • A pH of 777​ is neutral
  • Acids range from 000​ to 777​, with closer to 000​ being more acidic
  • Alkalis range from 777​ to 141414​, with closer to 141414​ being more alkaline


Science; Acids and alkalis; KS3 Year 7; The pH scale and indicators
1.
More acidic
2.
Neutral
3.
More alkaline



Indicators change colour depending on pH

Litmus paper is a common indicator and can tell whether a solution is an acid or alkali but not the how strong it is. Acid turns litmus paper red and alkalis turn it blue. 


Science; Acids and alkalis; KS3 Year 7; The pH scale and indicators
1.
Litmus paper strips
2.
Acidic litmus test result
3.
Alkaline litmus test result


Universal indicator shows us whether a solution is acidic or alkaline and how strong it is. The colour given by universal indicator matches that of the pH chart. 

Read more

Learn with Basics

Learn the basics with theory units and practise what you learned with exercise sets!
Length:
Properties of the three states of matter

Unit 1

Properties of the three states of matter

Physical and chemical properties

Unit 2

Physical and chemical properties

Jump Ahead

Score 80% to jump directly to the final unit.

Optional

The pH scale and indicators

Unit 3

The pH scale and indicators

Final Test

Test reviewing all units to claim a reward planet.

Create an account to complete the exercises

FAQs - Frequently Asked Questions

What does the pH scale show?

The pH scale shows the acidity / alkalinity of a solution.

What is the pH range for acids?

The pH of acids ranges from 0 to 7.

What is the range for the pH scale?

The pH scale ranges from 0 - 14.

©2020 - 2024 evulpo AG

Beta