Chemical ReactionsJaz Quevedo

Chemical Reactions

What are Chemical Reactions? Types of Reactions Conditions for reactions Balancing Equations

Chemical Reactions

A chemical reaction is the process in which the atoms of one or more substances are rearranged to form different substances.

A physical change indicates a chemical change. o Indicators of a chemical reaction:• Change of color• Temperature change• Release of light

Chemical Reactions

Endothermic

Absorb energy Products have more

stored energy than the reactants.

2H2O 2H2 + O2

Exothermic

Release Energy Reactants have more

stored energy than the products.

2H2 + O2 2H2O

Chemical Reactions

3Ni(SO4)

Coefficient – the amount of molecules on the equation.

Subscript – the number of atoms of the element at the time

Chemical Reactions

The reactants are the initial compounds that react together.

The products are the final compounds; they are what the reactions produced.

2H2 + O2 2H2O R

P

Chemical Reactions

↔ → +Separates reactants from Separates Separates

twoProducts and indicates a reactants or more

reactantsreverse reaction. from products. or

products.

Types of Reactions

Synthesis reaction – a chemical reaction in which two or more substances (A and B) react to produce a single product (AB).

A + B AB 2Na + Cl2 2NaCl

Types of Reactions

Decomposition reaction – a reaction in which a single compound (AB) breaks down into two or more elements or new compounds (A and B).

AB A + B CuCO3 CuO + CO2

Types of Reactions

Single-replacement reaction – a reaction in which the atoms of one element replace the atoms of another element in a compound.

A + BC B + AC Double-replacement reaction – two

substances replaces other two substances in a compound.

AC + BD BC + AD

Types of Reactions

Oxidation-reduction reactions, or also known as REDOX Reactions, are chemical reactions that involve a transfer of electrons.

They all include oxygen, and an atom always gets oxidized or reduced.

The substance that gains electrons, is reduced; the substance that loses electrons, is oxidized.

Combustion is a REDOX Reaction in which a substance combine with oxygen and releases heat and light.

Conditions for Reactions

Increase of temperature Concentration of the reactants Increase of surface area Catalyst

Conditions for Reactions

Increase of temperature If particles have less energy, there are less frequent and

successful collisions. If particles have high energy, more frequent and successful

collisions happen.

Conditions for Reactions

Concentration of the reactants Low concentration = few collisions High concentration = more collisions

Conditions for Reactions

Increasing of surface area

Conditions for Reactions

A catalyst is a substance that increases the rate of a reaction, but does not undergo a chemical change during the reaction.

Balancing Equations

How do you balance an equation? 1) Write the equation down.2) Draw a line separating the reactants from the

products (this will make it easier).3) Write down the number of atoms per element

on each side of the equation.4) Use your math knowledge to make all elements

equal on both sides by adding coefficients to the equation.

Balancing Equations

Fe + H2O Fe3O4 + H2

3Fe + 4H2O Fe3O4 + 4H2

Balancing Equations

Balance the following equations 2Mg + HCl MgCl2 + 2H2

Zn + Ag(NO3) Zn (NO3)2 + Ag H3(PO4) + Ba(OH)2 Ba3(PO4)2 + H2O C2H6 + O2 H2O + CO2

Ag(NH3)2CL + HNO3 NH4NO3 + AgCl

Bibliography