1. Section 8-1 Describing Chemical Reactions

2. Chemical Reactions Watch closely Record all indications of a chemical reaction.

3. Write a word equation… Silver nitrate reacts with sodium chloride dissolved in water to form silver chloride and sodium nitrate Silver nitrate + sodium chloride  silver chloride + sodium nitrate

4. Now a formula equation… Silver nitrate reacts with sodium chloride dissolved in water to form silver chloride and sodium nitrate Silver nitrate + sodium chloride  silver chloride + sodium nitrate AgNO 3 (aq) + NaCl(aq)  AgCl(s) + NaNO 3 (aq)

5. Chemical Reactions Watch closely Record all indications of a chemical reaction.

6. Try writing a word equation potassium metal reacts with water to produce aqueous potassium hydroxide and hydrogen gas. Potassium + water  potassium hydroxide + hydrogen

7. Now a formula equation… potassium metal reacts with water to produce aqueous potassium hydroxide and hydrogen gas. Potassium + water  potassium hydroxide + hydrogen K (s) + H 2 O  KOH (aq) + H 2 (g)

8. Chemical Reactions Watch closely Record all indications of a chemical reaction. (NH 4 ) 2 Cr 2 O 7 (s) → N 2 (g) + Cr 2 O 3 (s) + 4H 2 O(g) Δ

9. Start with a word equation… The reactant, Ammonium dichromate is heated to yield the products nitrogen, chromium(III) oxide, and water Ammonium dichromate  nitrogen + chromium(III) oxide + water Δ

10. Turn the word equation into a formula equation… The reactant, Ammonium dichromate is heated to yield the products nitrogen, chromium(III) oxide, and water (NH 4 ) 2 Cr 2 O 7 (s) → N 2 (g) + Cr 2 O 3 (s) + H 2 O(g) Δ

11. Turn the word equation into a formula equation… Our formula equation states the facts, and gives the correct chemical formulas for the reactants and products. What are we missing? (NH 4 ) 2 Cr 2 O 7 (s) → N 2 (g) + Cr 2 O 3 (s) + H 2 O(g) Δ

12. All Equations Can Be Translated Into A Sentence 2HgO(s) → 2Hg(l) + O 2 (g) When heated, solid mercury (II) oxide yields liquid mercury and oxygen gas.

13. Example #1 Solid sodium combines with chlorine gas to produce solid sodium chloride.

14. Example #2 When solid copper reacts with aqueous silver nitrate, the products are aqueous copper (II) nitrate and solid silver.

15. Example #3 In a blast furnace, the reaction between solid iron (III) oxide and carbon monoxide gas produces solid iron and carbon dioxide gas.