Understanding Chemical Equations: Balancing and Practice

1. Chapter 10: Sec 1: Chemical Reactions • How can you tell there is a chemical Change? • Temperature • Light • Color • Gas Bubbles

2. The Chemical Equation: Section 1 Chemical Equations: What do we start with? • Reactants = Starting substances • Products = Substances formed Coefficient: • Represent the lowest whole number ratio of the amounts of all the reactants and products

3. The Word Equation • Describing the reaction Reactant 1 + Reactant 2 --> Products Iron(s) + chlorine(g) --> Iron (III) chloride(s) • How is this Read: Iron and chlorine react to produce iron (III) chloride

4. The Skeleton Equation • Replace the words with the symbols • Iron(s) + chlorine(g) --> Iron (III) chloride(s) • Fe(s) • + • Cl2(g) • --> • FeCl3(s) • Whats Wrong with this Equation? • Count the number of atoms on each side of the arrow. • Needs to be balanced! • let’s practice skeleton equations first

5. Practice Makes Perfect • Write the skeleton equations for the following word equations • hydrogen(g) + bromine(g) --> hydrogen bromide (g) • Br2(g) • --> • HBr(g) • H2(g) • + • carbon monoxide(g) + oxygen(g) --> carbon dioxide(g) • CO(g) • + • O2(g) • --> • CO2(g) • potassium chlorate(s) --> potassium chloride(s) + oxygen(g) • + • KClO3(S) • --> • KCl(S) • O2(g)

6. Cl • Fe(s) • + • Cl2(g) • --> • FeCl3(s) The Balanced Chemical Equation • Fe • Cl • Cl • Remember: Matter is neither created nor destroyed • Count the number of atoms of each element • Cl • + • --> • Fe • Cl • What’s the Problem?

7. Cl • Cl • Cl • Cl • Cl • Fe(s) • + • Cl2(g) • --> • FeCl3(s) How do We Fix It? • Cl • Cl • Cl • Fe • Fe • Cl • Cl • Balance the equation • Cl • Cl • 2 • 3 • 2 • Fe • + • --> • Fe • Now Count the atoms. • Remember: Matter is neither created nor destroyed. Law of conservation of mass

8. 5 Easy Steps for Balancing Equations • Write the skeleton equation • Count the atoms of the reactants • Count the atoms of the the products • Place coefficients to make the # of atoms equal on both sides of the equation • Write the coefficients in their lowest possible ratio

9. Practice • Write chemical equations for each of the following reactions • In water, Iron (III) chloride reacts with sodium hydroxide, producing solid iron (III) hydroxide and sodium chloride.

10. Liquid carbon disulfide reacts with oxygen gas, producing carbon dioxide gas and sulfur dioxide gas.

11. Solid zinc and aqueous hydrogen sulfate reat to produce hydrogen gas and aqueous zinc sulfate.