Chemical Reactions

• Define chemical equation and identify its components.

• Interpret information from a chemical equation's structure.

• State Law of Conservation of Mass; see its use in balanced equations.

• Differentiate open and closed systems in chemical reactions.

• A chemical equation is a shorthand for chemical reactions.

• It shows reactants (inputs) and products (outputs) of a reaction.

• Rust example: 4Fe + 3O₂ → 2Fe₂O₃ (Iron + Oxygen → Iron Oxide).

• Symbols (like H₂O) are like text abbreviations (like 'jk').

What is a Chemical Equation?

• Formulas show molecules using symbols and subscripts.

• Element symbols are 1 or 2 letters (H for Hydrogen).

• Subscripts show atom counts. No subscript means one atom.

• H₂O: 2 H atoms, 1 O atom. NH₃: 3 H atoms, 1 N atom.

Chemical Formulas

• Reactants (left) form products (right), separated by a 'yields' arrow (→).

• Plus signs (+) separate items. General form: Reactant + Reactant → Product + Product.

• Coefficients (numbers in front) show particle count and balance equations.

• N₂ + 3H₂ → 2NH₃: 1 nitrogen & 3 hydrogen molecules make 2 ammonia.

Structure of a Chemical Equation

• Matter isn't made or lost in chemical reactions!

• Total mass before a reaction equals total mass after.

• Atoms rearrange to form new stuff; none disappear.

• Balanced equations (e.g., Fe + S → FeS) show this rule.

Law of Conservation of Mass

​​Open Systems

• Nothing gets in or out – it's sealed tight!

• Everything stays locked inside, safe and sound.

• Perfect for scientists to weigh things precisely!

​​Closed Systems

• Matter & gases can freely move in or out.

• Like a plant in an open pot breathing air.

• Weighing is tricky if gases can escape!

​Here's the Deal!

• Mass is always conserved; it just changes form.

• Coefficients show the number of molecules or atoms.

• The arrow (→) means 'yields' or 'reacts to form'.

• Atoms only rearrange; none are made or destroyed.
  

​Oops! Not Quite...

• Mass is lost or gained in chemical reactions.

• Coefficients in equations show the mass of substances.

• The reaction arrow (→) simply means 'equals'.

• New atoms are created during chemical reactions.
  

• Chemical equations use symbols and formulas for reactions.

• Reactants are on the left, products on the right.

• Coefficients balance equations, showing molecule counts.

• Law of Conservation: Matter isn't created or destroyed.