Changes in matter?How can it be?

A physical change does not affect the nature or the characteristic properties of matter Properties are retained Examples:

Phase change Dissolution Deformation

Physical Changes

A chemical change changes the nature and characteristic properties of matter Properties are not retained Molecules are broken down and new ones are formed Chemical changes can also be called reactions Examples:

Synthesis Decomposition Precipitation Combustion Oxidation

Chemical Change

The release of a gas The release or

absorption of heat The emission of light A change in color The formation of a

precipitate

Signs of a Chemical Change

The release of a gas The release or absorption of heat The emission of light A change in color The formation of a precipitate

Warning!

PHYSICAL CHANGES CAN SOMETIMES SHOW THESE SIGNS AS WELL

Acid-Base Neutralization Synthesis Decomposition Combustion Precipitation

Types of Chemical Reactions

Acid Base neutralization

Let’s try one on our own

Which of the following reactions is an acid-base neutralization?

2 Na(s) + Cl2(g) 2 NaCl(s)

2 HI(aq) + Ba(OH)2 BaI2(aq) + 2 H2O(l)

MgCl2(aq) + Na2SO3(aq) MgSO3(s) + 2 NaCl(aq)

2 HCl(aq) + Mg(OH)2(aq)

HNO3(aq) + KOH(aq)

HBr(aq) + NaOH(aq)

Complete the following Acid-base Neutralizations

Synthesis: two or more reactants come together to form a new product.

◦ Ex: N2(g) + 2O2(g) 2NO2(g)

Decomposition: A single reactant is broken up into two or more products.

◦ 2H2O (l) 2H2 (g) + O2(g)

Synthesis and Decomposition

Single Displacement: A new compound is formed by the movement of one element or ion from one compound into a new one.

Double Displacement: Two ionic compounds switch cations(Positive ion).

Single and Double Displacement Reactions

AgNO3 + NaCl → AgCl + NaNO3

3 Mg (s) + 2 AlCl3 (aq) → 2 Al (s) + 3 MgCl2 (aq)

Pb(NO3)2 (aq) + 2KCl (aq) → 2KNO3 (aq) + PbCl2 (s)

Single or double?

Chemical reactions involving oxygen or a substance with similar properties.

Which other elements could act similarly to Oxygen?

Oxidation

Examples of Oxidation

What is wrong here?

This type of chemical reaction involves the release of a large amount of energy.

Combustion: A type of Oxidation

The Oxidizing Agent

The Ignition Temperature

The Substance to be burnt (will release a lot of energy in the presence of oxygen)

Rapid Combustion: Within a short period of time, a lot of energy is released. (Light and heat energy, ex: fire)

Spontaneous Combustion: A rapid combustion in which the fuel reaches its ignition temperature without energy from an outside source. (No need to light the fuel)

Slow Combustion: A slow oxidation reaction such as decomposition, rusting, cellular respiration, etc.

Types of Comubstion

Slow Rapid

A reaction in which a solid precipitate is formed from two non-solid reactants.

Ex: NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)

Precipitation

Last week in the lab, you carried various chemical and physical changes. 1. Heating and cooling of iodine2. Mixing of iron and sulfur3. Burning of iron and sulfur4. Mixing of NaOH and CaCl2

5. Mixing of HCl and CaCO3 (marble chips)

You must determine whether you observed a chemical or a physical change.

For each of the chemical changes observed you must:

◦ Provide evidence for how you determined that this was a chemical change (signs).

◦ Identify the type of chemical change that you observed (when possible).

◦ A balanced chemical equation for each of the reactions you carried out.

Your task (submitted on a loose leaf):