Balancing Equations

This page focuses on the crucial skill of balancing chemical equations, which is a fundamental concept in GCSE Chemistry revision notes.

The page provides several examples of unbalanced equations and demonstrates how to balance them:

Example: KOH + CO₂ → K₂CO₃ + H₂O

To balance this equation:

1. Count the number of each type of atom on both sides
2. Add coefficients to ensure equal numbers of each atom type on both sides

Highlight: When balancing equations, the number of atoms of each element must be the same on both sides of the arrow.

The page includes more complex examples, such as:

Example: Al + H₂SO₄ → Al₂(SO₄)₃ + H₂

This exercise in balancing equations helps students develop a crucial skill for understanding chemical reactions and stoichiometry, which is essential for both GCSE and A Level Chemistry studies.

Chemical and Physical Changes

This page delves into the differences between chemical and physical changes, and introduces important calculations in chemistry. It's an essential part of GCSE Chemistry revision notes.

Definition: Chemical change occurs when a chemical reaction takes place, rearranging atoms to form new chemicals without creating or destroying atoms.

Definition: Physical change is when a substance changes without becoming a new chemical, often occurring during processes like melting, freezing, boiling, condensing, and dissolving.

The page also covers key calculations and equations:

Highlight: 1 mole = 6.02 x 10²³ particles

It introduces concepts like molar volume, yield, and atom economy, which are crucial for A Level Chemistry Revision.

Example: Molar volume at room temperature and pressure (rtp) = 24dm³

The page also includes a formula for calculating average relative formula mass:

Ar = √(M₁ x α₁) + (M₂ x α₂) / 100

This information provides a solid foundation for understanding chemical reactions and calculations, essential for both GCSE and A Level Chemistry students.

Energy Efficiency and Electrical Safety

This page covers topics related to energy efficiency in homes and electrical safety, which are important practical applications of physics concepts.

The page begins with a discussion on loft insulation:

Example: Glass fibre insulation is placed on the floor of the loft. It contains trapped air, which is a poor heat conductor, reducing heat losses and convection currents in the roof space.

The page then moves on to electrical safety, explaining the function of different wires in electrical systems:

Definition: A fuse breaks the circuit if a fault in a device causes too much current to flow. It contains a wire that heats up and melts if there is excessive current.

Vocabulary:

• Live wire: Carries current to the house/appliance at a high voltage (brown wire)
• Neutral wire: Completes the circuit and carries current away at low/zero voltage (blue wire)
• Earth wire: Can carry current safely into the ground if a fault develops (green and yellow striped wire)

This information is crucial for understanding energy efficiency and electrical safety, which are important practical applications of physics concepts for GCSE Physics students.