Class notes - Science Worded Equations

Writing equations
Describing change
To describe a change we see, rather than write an equation to represent a
change we have observed.
Change described in equation.
What materials I start with —> What materials I end with

Examples
An ice block, when heated, turns into liquid water.
= Solid water —Heat—> Liquid water
Liquid wax, when heated, turns into gaseous wax.
= Liquid wax —Heat—> Gaseous wax
If I drop a magnesium strip into hydrochloric acid, I produce magnesium
chloride and hydrogen gas.
= Magnesium + Hydrochloric acid —> Magnesium chloride + Hydrogen gas
If I pass electricity through water, I produce oxygen and hydrogen gas.
= Water —Electricity —> Oxygen gas + Hydrogen gas
Lead iodide and potassium nitrate are produced when I mix lead nitrate and
potassium iodide together.
= Lead nitrate + Potassium iodide —> Lead iodide + Potassium

Parts
In a chemical reaction, the materials we begin with are called reactants.
The materials that we end up with are called the products.
= Reactants —Yeilds/react to/create—> Products

Note
Heat and electricity are not listed as reactants, they create the reaction to occur
but are not a participant.

States in an equation
When we write out an equation to describe change, we also put in the states.
- Solid (s).
- Liquid (l).
- Gas (g).
- Aqueous (aq). —> Dissolved in water = Solution.
Example: Water (s) —Heat—> Water (l) —Heat—> Water (g)
States aren’t capital, they are subscripts (Small).

Terms
Block = Solid.