Chemical reactions & equations

你需要知道的

• A word equation names the reactants and products; a symbol equation replaces each name with its formula.
• A balanced equation has the same number of each type of atom on both sides of the arrow, because atoms are only rearranged.
• You balance an equation by putting numbers in front of formulae, never by changing the small subscript numbers.
• Changing a subscript changes the substance itself, e.g. H2O (water) would become H2O2 (hydrogen peroxide).
• A simple tally chart of atoms on each side helps you balance equations such as N2 + 3H2 → 2NH3.

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