Chemistry ReactionsBy: Mr. Anthony Gates

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)

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)

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

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:

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?

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.

Check Your Understanding

Will this yield a product and if so, what?

• ???

Will this yield a product and if so, what?

• ???

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)

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

Peculiar situation

• Whenever a double replacement reaction causes Hydrogen to be paired with a carbonate ion, they will instead form carbon dioxide and water.

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

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.

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!

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.

You try…

• Aluminum metal combines with oxygen gas to become aluminum oxide.

Let’s try some more…

Magnesium Chlorate decomposes into magnesium chloride and oxygen gas.

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.

You try…

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

How about some more practice?

• Beryllium metal reacts with oxygen gas to produce beryllium oxide.

Predicting Products

Combination/Synthesis:

• Two or more individual elements react to create a single product.

• A+BAB• Example:

Predicting Products

Decomposition:

• One compound breaks up into multiple compounds or elements.

• ABA+B

• Example:

•

Predicting Products

Combustion:

• Some compound (usually containing carbon and hydrogen) reacts with Oxygen to create only carbon dioxide and water.

• Example:

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+BCAC+B

• Example:

•

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+CDAD+CB

• Example:• ??

Now you try…

• 2

•

How about we try some more…