Chapter #8

Chemical

Equations and Reactio

ns

NearingZero.Net

Chapter 8.1 Describing Chemical Reactions

• Parts of an equation• Reactants Products

• Mg + O2 MgO + energy

• Word Equation:• Magnesium and oxygen yields magnesium

oxide and energy

• *pg 246 symbols used in Chemical Equations

Yields

• Chemical equation represents, with symbols and formulas, the identities and relative amounts of the reactants and products in a chemical reaction.

• Indications of a Chemical Reaction

1. Evolution of heat and light2. Production of gas3. Formation of a precipitate.

Characteristics of Chemical Equations

1. The equation must represent known facts

2. The equation must contain correct formulas for the reactants and products

3. The law of conservation of mass must be satisfied. (Balanced equation)

• Word equation -represents the reactants and products using words.

• Formula equation -represents the reactants and products using symbols or formulas.

• Balanced equation -is the formula equation with added coefficients to satisfy the law of conservation.

• Conservation of mass - atoms can be neither created or destroyed.

• The numbers of atoms of each element must be the same on both sides of the yields.

• No mass is lost or gained.

Balancing Equations1. Write the word

equation2. Make a T-chart3. Put the number of

each element on the t-chart

4. If the # of atoms are not the same you need to balance. You can only add COEFFICIENTS (Big #)

5. Check work! Count all #’s of each element.

• H2 + O2 H2O• Hydrogen + oxygen

yields water (dihydrogen monoxide)

• H2 + O2 H2O

H

O

2

2

2

1

Left Right

2

H

O

2

2

2

1

4

2

2

4

8.2 Types of Chemical Reactions

• 5 types of reactions1. Synthesis2. Decomposition3. Single replacement4. Double replacement5. Combustion

• Synthesis • A + B C• 2 or more simple

substances combine to form a new complex substance.

• Decomposition• C A + B• A complex

substance breaks down into 2 or more simpler substances.

• Single Replacement

• A + BX AX + B

• An uncombined element replaces an element that is part of a compound.

• Double Replacement

• AX + BY AY + BX

• Different atoms in 2 different compounds replace each other.

“Likes replace Likes”

Combustion• Hydrocarbons are compounds made up

of carbon and hydrogen• Hydrocarbon + Oxygen Carbon Dioxide and

Water

Slide 12-15Put on your note

cards!!!• Synthesis1. Reactions of elements with oxygen

produces an OXIDE2. Reactions of two nonmetals forms a

covalent compound3. Reactions of metals with nonmetals

other than oxygen produces an ionic compound

4. Oxides of active metals react with water to produce metal hydroxide.

Decomposition1. Binary compounds breakdown into its

elements.2. Electrolysis-same as #13. Decomposition of metal carbonates to

produce metal oxide and carbon dioxide

4. Decomposition of metal hydroxide to produce metal oxide and water

5. Decomposition of metal chlorates to produce metal chloride and oxygen

6. Decomposition of acids to produce water and whatever is left

Single Replacement1. Replacement of a metal by a more

reactive metal2. Replacement of hydrogen in water by

a metal to produce metal hydroxide and hydrogen

3. Replacement of hydrogen in an acid by a metal to produce hydrogen and metal compound

4. Replacement of halogens: 1 halogen replaces another halogen.

• Double Replacement- “Likes replace likes”. Metals replace metals

• Combustion-always produce carbon dioxide and water

8.3 Activity Series of the Elements

• Activity series-is a list of elements organized according to ease with which the elements undergo certain chemical reactions.

React with cold water and acids, replacing hydrogen. React with oxygen, forming oxides.

React with steam and acids, replacing hydrogen. React with oxygen, forming oxides.

Do not react with water. React with acids, replacing hydrogen. React with oxygen, forming oxides.React with oxygen, forming oxides.

Fairly unreactive, forming oxides only indirectly.

Examples: MgCl2(aq) + Zn (s) Zn is alone it wants to take Mg place. Can it?????

Al (s) + H2O (g)

The higher up on the chart the stronger it is!!!!

King of the mountain

Work Cited• “Cartoon”. Aug. 11, 2006.

http://www.nearingzero.net/sbunch3.html

• “Activity Series”. http://www.pennmanor.net/schools/hs/canady/web_page_web_class/taylor_portfolio_webpage/Chemistry/chemistry/reactions/activity_series.jpg