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4Fe + 3O 2 → 2 Fe 2 O 3. What do you notice about the atoms in this equation?. Word Equation: Acetic acid + sodium hydrogen carbonate --→ sodium acetate + water +carbon dioxide Chemical Equation: H 2 C 2 H 3 O 2 + NaHCO 3 --→ NaC 2 H 3 O 2 + H 2 O + CO 2 Reactant Product
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4Fe + 3O2 → 2 Fe2O3 What do you notice about the atoms in this equation?
Word Equation: Acetic acid + sodium hydrogen carbonate --→ sodium acetate + water +carbon dioxide Chemical Equation: H2C2H3O2 + NaHCO3 --→ NaC2H3O2 + H2O + CO2 Reactant Product “produces” or “yields” Subscript: H2O – tells you how many of one particular atom Coefficient: 2H2O – tells you how many molecules
Balancing Act Atoms are not CREATED or DESTROYED during a chemical reaction. • Scientists know that there must be the SAME number of atoms on each SIDE of the EQUATION. • To balance the chemical equation, you must add COEFFICIENTS in front of the chemical formulas in the equation. • You cannot ADD or CHANGE subscripts!
How to Balance Equations: • Step 1: Determine number of atoms for each element. • Step 2: Pick an element that is not equal on both sides of the equation. • Step 3: Add a coefficient in front of the formula with that element and adjust your counts. • Step 4: Continue adding coefficients to get the same number of atoms of each element on each side.
Mg + O2 → MgO Step 1: Determine number of atoms for each element. Mg = 1 Mg = 1 O = 2 O = 1
Mg + O2 → MgO Step 2: Pick an element that is not equal on both sides of the equation. Mg = 1 Mg = 1 O = 2 O = 1 Since the O atoms are not equal, we’ll target those first!
Mg + O2 → MgO 2 Step 3: Add a coefficient in front of the formula with that element and adjust your counts. Mg = 1 Mg = 12 O = 2 O = 12 Adding a 2 in front of MgO will change the number of atoms on the product side of the equation.
Mg + O2 → MgO 2 2 Step 4: Continue adding coefficients to get the same number of atoms of each element on each side. Mg = 12 Mg = 12 O = 2 O = 12 Now we need to increase the number of Mg atoms we have on the reactant side. Adding a 2 in front of Mg will give us 2 atoms of Mg and balance the equation.
Your Turn: Balance the following equations. Be sure to show your work! • ____ Ca + ____ O2 → ____ CaO • ____ N2 + ____ H2 → ____ NH3 • ____ Cu2O + ____ C → ____Cu + ____ CO2 • ____ H2O2 → ____ H2O ____ O2