changes in matter?
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Changes in matter?. How can it be? . Physical Changes . A physical change does not affect the nature or the characteristic properties of matter Properties are retained Examples: Phase change Dissolution Deformation . Chemical Change. - PowerPoint PPT PresentationTRANSCRIPT
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):