Chapter 8 Section 1.2 & Section 2

Chapter 8 Section 1.2

Section 2​

Multiple Choice

What term represents with symbols and formulas the identities and relative molecular or molar amounts of the reactions and products in a chemical reaction?

• A chemical Equation

• A Reaction Write up

• A Balancing exercise

• Equation Symbols

Multiple Choice

Which of the following indicate that a chemical reaction has taken place?

• Release of energy as heat

• Release of energy of light

• Production of Gas

• All of the above

Tips to Balancing Equations Easily

• Go through each atom one at a time, don't try to do multiple at once

• First balance the atoms that are combined on one side of the equation and only appear once

• Balance Polyatomic ions as single units

• Balance hydrogen and oxygen atoms last​

Symbols Used in chemical equations

• Sometimes different symbols are used in chemical equations to indicate different things

• These often tell us the specifics of what happens in a reaction​

  • Some indicate the presence of a catalyst

    • Catalyst: a substance that changes the rate of a chemical reaction, but can be recovered unchanged

      • Catalyst does not affect the product itself, but makes it go faster​

Significance of a chemical equation

• A chemical equation is similar to an algebraic equation, and can be used to solved for quantities

• Information Revealed

  • The coefficients of a chemical reaction indicate the relative, not absolute amounts of reactants and products

    • Multiplying all the coefficients by t​he same value allow us to scale up an reaction

  • We can determine the Minimum relative masses of the reactants and products in an equation​

Calculating the Mass Example

Section 2: Types of Chemical Reactions

• We classify reactions into different types based on what happens in them

  • The types we will discuss in this class

    • Synthesis

    • Decomposition

    • Single Displacement

    • Double Displacement

    • Combustion​

Synthesis Reactions

• In Synthesis reaction two or more substances combine to form a new compound

  • Represented by the following general equation: A + X --> AX

• Reactions of elements with Oxygen

  • One simple type of synthesis is the combination of an element with oxygen to form an oxide​

    • Almost all metals react to form oxides​

  • Most metals react with the halogens (group 17) to form compounds​

Decomposition Reactions

• In Decomposition Reactions, a single compound undergoes a reaction that produces two or more simpler substances

  • Shown by the general equation AX --> A + X​

  • Most only take place when energy is added to the system

    • Electrolysis: the decomposition of a substance by an electric current​

• Binary compounds: break down into elements

• Metal carbonates: break down to produce carbon dioxide and metal oxide

• Metal hydroxides: break down to produce metal oxides and water

• Metal chlorates: yield metal chloride and oxygen

• Acids : Acids break down into nonmetal oxides and water

  • See pages 279-280 for each​

Single Displacement

• In a Single Displacement reaction one element replaces a similar element in a compound

  • Shown by the general equation A + BX --> AX+B

• ​Displacement of a metal by another metal: One metal replaces another

• Displacement of hydrogen in water by a metal

  • Water forms a hydroxide with a metal

• Displacement of hydrogen in an acid by a metal

  • Metals replace the hydrogen in the acid

• Displacement of halogens

  • One halogen replaces another-in the periodic table, the smallest halogen will replace the larger one

Double Displacement Reactions

• In a Double Displacement reaction the ions of two compounds exchange places in an aqueous solution to form two new compounds

  • Represented by the equation: AX + BY --> AY + BX​

  • ​Leads to a formation of a Precipitate

  • In some double displacement reactions, one of the products is a gas

    • Some result in liquid water as well​

Combustion Reactions

• In a Combustion reaction, a substance combines with Oxygen, releasing a large amount of energy in the form of light ant heat

  • The reactants tend to be hydrocarbons, Chemicals only containing Carbon and Hydrogen​

  • Products are usually Carbon Dioxide and Water​, but carbon monoxide may also be a product

• Combustion reactions are often used to generate energy​

Multiple Choice

This type of reaction results in two or more reactants making one new substance

• Synthesis

• Decomposition

• Single Displacement

• Double Displacement

• Combustion

Multiple Choice

This type of reaction results in two Compounds switching or "trading" one of their ions.

• Synthesis

• Decomposition

• Single Displacement

• Double Displacement

• Combustion

Multiple Choice

This type of reaction results in one reactant undergoing a change that results in two or more products

• Synthesis

• Decomposition

• Single Displacement

• Double Displacement

• Combustion

Multiple Choice

This type of reaction results in one reactant replacing an ion on one of the other reactants

• Synthesis

• Decomposition

• Single Displacement

• Double Displacement

• Combustion

Multiple Choice

This type of reaction results in Heat, light, carbon dioxide and water as products

• Synthesis

• Decomposition

• Single Displacement

• Double Displacement

• Combustion