Lemonade-Ed - Lesson: Conservation of Mass & Balancing Equations

Lemonade-Ed

Lesson Plan: Conservation of Mass & Balancing Equations

Navigate the knowledge tree: 🌿 Chemistry ➡ Chemical Changes ➡ Ions

Hei Mahi (Do Now)

Do Now on your Whiteboard

Write the formula for the following ionic compounds:

1. Magnesium chloride

2. Aluminium oxide

3. Sodium chloride

Hei Mahi (Do Now) ANSWERS

Do Now on your Whiteboard

Write the formula for the following ionic compounds:

1. Magnesium chloride MgCl₂

2. Aluminium oxide Al₂O₃

3. Sodium chloride NaCl

Knowledge: Word Equations

Scientists use word and symbol equations to describe and summarise what happens in a reaction.

The reactants, or substances that take part in the reaction, are written on the left.
An arrow sign '→' to show that a chemical reaction occurs.
The products, or substances produced in the reaction, are written on the right.
A plus sign '+' to take the place of 'and'.

In a word equation, the names for all the substances are written out in full. In a chemical equation, chemical sumbols (from the periodic table) or formulae of each substance are used instead of their names.

Go to 🌿 Chemical Reactions

Activity: sciPad

Complete sciPad pages 18 'Chemical Word Equations'.

Knowledge: Law of Conseration of Mass

Atoms cannot be created or destroyed. In a chemical reaction, atoms can only be rearranged from those at the start of the reaction.
Chemical equations show this by having the same number of atoms on each side of the equation. This is called balancing an equation.

Below are some simple rules for writing and balancing equations:

Small numbers after an atom's symbol tell you how many atoms are combined. For example: O₂ means two oxygen atoms combined; O₃ means three oxygen atoms combined.
Large numbers in front (called the co-efficient) mean more than one of whatever follows. For example 3O₂ means three oxygen molecules, each with the formula O₂.
You can't alter a formula to balance an equation. You can only change the numbers (co-efficient) in front.

Go to 🌿 Law of Conservation of Mass