Reactants vs Products
Identify what changes and what forms
Setting up the bench…
What this lesson covers
Why it matters
Grey iron and yellow sulphur sit side by side, unchanged. Heat them and they fuse into black iron sulphide — the starting stuff became something new.
Predict first
In 'Iron + Sulphur → Iron sulphide', which are the reactants?
Reactants are what you start with (left of the arrow); products are what's formed (right). Here Fe + S → FeS.
- Iron and sulphur — the starting substances — correct
- Iron sulphide
- The heat
What you do
Heat the iron and sulphur. Watch the grey-and-yellow reactants turn into the black product, iron sulphide.
Check yourself
In Fe + S → FeS, the product is…
The product is what forms — iron sulphide, on the right of the arrow.
Reactants are written…
Reactants → products: starting substances on the left.
How do you know a new substance formed?
New properties (black, non-magnetic) prove a chemical reaction happened.
- FeS (iron sulphide) — correct
- Fe and S
- the heat
- on the left of the arrow — correct
- on the right of the arrow
- below the arrow
- FeS is black and non-magnetic, unlike its parts — correct
- it weighs less
- nothing changed