Chemistry Reactions

1. Chemistry Reactions By: Mr. Anthony Gates

2. Types of Reactions Combination (Synthesis) Reaction: chemical change in which two or more substances react to form a single new substance. • Format: • A + B  AB • Example: • 2 H2 (g)+ O2 (g)  2 H2O (l)

3. Types of Reactions Decomposition Reaction: chemical change in which a single compound breaks down into two or more simpler products. • Format: • AB  A + B • Example: • 2 H2O (l)  2 H2 (g)+ O2 (g)

4. Types of Reactions Combustion Reaction: chemical change in which an element or a compound reacts with oxygen, often producing energy in the form of heat and light. • This change contains some form of carbon as a reactant, thus it usually produces water and carbon dioxide. If there isn’t enough oxygen, carbon monoxide may be produced instead of carbon dioxide. • Example: • CxHyOz + O2  CO2 + H2O + heat

5. Types of Reactions Single Replacement Reaction: chemical change in which one element replaces a second element in a compound. • Either a metal will replace a metal in a compound or a nonmetal will replace a nonmetal in a compound. A metal will not replace a nonmetal and vice versa. • Format: • A + BC  AC + B • Example:

6. Inquiring minds must know… • If a metal can replace another metal in reaction, do reactions constantly occur so long as multiple metals are present? • No! Every element is different in structure thus each of them has a varying degree of reactivity. • So how do we know when a metal will perform a single replacement reaction?

7. Activity Series • List of metals and some nonmetals by decreasing reactivity. • The elements that can hold onto electrons tighter are less likely to react. The more likely an element is to give up its electrons, the more reactive it is. • Any metal will replace another metal that is below it on the activity series, but not one that is above it. • So Iron (Fe) will replace Copper (Cu) in a reaction, but will not replace Zinc (Zn) or Calcium (Ca). • The same pattern will occur for halogens, but only to replace another halogen.

8. Check Your Understanding Will this yield a product and if so, what? • ??? Will this yield a product and if so, what? • ???

9. Types of Reactions Double Replacement (Displacement) Reaction: chemical change involving an exchange of positive ions between two compounds. • Format: • AB + CD  CB + AD • Example: • 2 NaOH (aq) + CuCl2(aq)  2 NaCl (aq) + Cu(OH)2(s)

10. Double Replacement (Displacement) Reaction • This form of reaction usually yields one of the following types of products: • Precipitate- a solid made that forms from an aqueous solution • Gas • Water

11. Peculiar situation • When ever a double replacement reaction causes Hydrogen to be paired with a carbonate ion, they will instead form carbon dioxide and water.

12. Solubility Rules! • Most Nitrates ( salts are soluble • Most salts of are soluble • Most Chloride (, Bromide , and Iodide salts are soluble … • Except with Silver (, Mercury , or Lead • Most Sulfate salts are soluble … • Except with Barium , Lead , or Calcium

13. Some solids just don’t want to dissolve… how rude! • Most Hydroxide compounds are only slightly soluble • Except for with Sodium , Potassium , Calcium • Most Sulfide , Carbonate , and Phosphate salts are only slightly soluble • Slightly Soluble compounds would rather stay or become a solid than be dissolved in solution… this usually causes a precipitate to form when these are created in a reaction.

14. Let’s simplify • Nitrate salts are soluble • Alkali metals and Ammonium salts are soluble • Halogen salts are soluble except with Silver, Mercury, or Lead. • Sulfate salts are soluble except with Barium, Lead, or Calcium. • , and salts are NOT soluble • Hydroxide is NOT soluble except with Calcium. • Anything that is soluble trumps what isn’t!

15. Describing a Reaction • Use your words… • Magnesium metal reacts with hydrochloric acid to produce magnesium chloride and hydrogen gas. • Hints: • Write out the name of each compound. • Who is reacting and who is being produced? • Now write is as a sentence.

16. You try… • Aluminum metal combines with oxygen to become aluminum oxide.

17. Let’s try some more… Magnesium Chlorate decomposes into magnesium chloride and oxygen gas.

18. How about the Reversal • Silver (I) Nitrate solution is added to sodium chloride to create a silver (I) chloride precipitate in a sodium nitrate solution. • Hints: • Draw the formulas of the compounds. • Who is reacting and who is being produced? • Put the formulas in order and add the appropriate symbols.

19. You try… • Tetracarbon octahydrogen gas is mixed with oxygen gas to form carbon dioxide gas and water vapor.

20. How about some more practice? • Beryllium metal reacts with oxygen gas to produce beryllium oxide.

21. Predicting Products Combination/Synthesis: • Two or more individual elements react to create a single product. • A+BAB • Example:

22. Predicting Products Decomposition: • One compound breaks up into multiple compounds or elements. • ABA+B • Example:

23. Predicting Products Combustion: • Some compound (usually containing carbon and hydrogen) reacts with Oxygen to create only carbon dioxide and water. • Example:

24. Predicting Products Single Replacement: • An individual element reacts with a compound to cause a switch between the single element and the similar part of the compound (cations with cations and anions with anions). • A+BCAC+B • Example:

25. Predicting Products Double Replacement: • Two compounds react with each other causing the anions to switch who they are bonded. This causes either a precipitate, a gas, or water to form. • AB+CDAD+CB • Example: • ??

26. Now you try… • 2

27. How about we try some more…