Hey there!
CH₄ + 2O₂ → CO₂ + 2H₂O
carbon dioxide: product
methane: reactant
oxygen: reactant
water: product
Methane and oxygen are reactants because they are the substances we start with. They are on the side of the equation that the arrow is pointing away from.
Carbon dioxide and water are products because they are the new substances that are the yields of the equation. They are on the side of the equation that the arrow is pointing towards.
Hope this helps!
The answer is true. It is the last star.
The best way to balance an equation is to balance one atom at a time.
You start with two Au atoms on the left, so you know the coefficient of Au on the right has to be 2. So at first we get,
Au2S3 + H2 --> 2Au + H2S
Then, notice you have 3 sulfur atoms on the left, so you need three on the right.
Our equation becomes
Au2S3 + H2 --> 2Au + 3H2S
Lastly, we now have six hydrogen atoms on the right, and only two on the left, so we assign a three to the H2 on the left
Au2S3 + 3H2 --> 2Au + 3H2S Is the balanced final equation.