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Study Guide: Types of Chemical Reaction s/ Reactions (Notes)
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Types of Chemical Reaction s/ Reactions (Notes)

By Fatskills Exam Guides Team — the exam nerds behind 28,500+ quizzes and 2.1M practice questions across 500+ global exams.

⏱️ ~3 min read

Synthesis
A+B-->AB

Example: hydrogen and oxygen combine and make water- 2H2+O2-->2H2O
2 molecules of hydrogen are needed to react with 1 molecule of oxygen to form 2 molecules of water.

Decomposition
AB-->A+B

More than one molecule of water is needed to start the reaction.
Example: When water decomposes, it makes hydrogen and oxygen gas- 2H2O-->2H2+O2
2 water molecules produce 2 molecules of hydrogen gas and 1 molecule of oxygen gas.

Single Replacement
AB+C-->A+BC
A+BC-->B+AC
Only one element is trading partners

Double Replacement
AB+CD-->AC+BD

*Two elements trade partners.
No mass is lost.

Combustion
CH4+2O2-->(energy release)--> CO2+2H2O

Compounds of hydrogen and carbon react with oxygen to form carbon dioxide and water.

What type of reaction is 2Mg+1O2-->MgO+Heat+Light
Synthesis

What type of reaction is 2H2O2-->2H20+1O2
Decomposition

What type of reaction is 1Mg+2HCl-->1MgCl2+1H2
Single Replacement

What type of reaction is NaOH+HCl--NaCl+HOH
Double Replacement

Why does a magnesium ribbon have a gray coating?
Has a coating of magnesium oxide

What happens when the temperature of magnesium is increased rapidly?
Bursts into flames when heated with a torch
Gray magnesium powder forms
Conversion of magnesium ribbon to magnesium oxide

Why does the temperature of magnesium increase rapidly? 
Raising starting temperature increases the kinetic energy
Raising kinetic energy allows reactants to go over the energy hill and transition into products.
*Reaction=Exothermic, resulting in making the potential energy of the products lower than the reactants.

How long does it take for hydrogen peroxide to break down on it's own?
Rate of 10% each year

What happens when potassium iodine is added to hydrogen peroxide?
Rapid breakdown of hydrogen peroxide with formation of oxygen gas bubbles
Change in pH from acid to neutral
Temperature increases

Why did whatever happened, happen when potassium iodine was added to hydrogen peroxide?
Took less kinetic energy to move the reaction away from the reactant products
*Release of energy measured as an increase in temperature indicates that the products have lower potential energy than the products.
Increase of temperature indicates that it's exothermic.

What happens when the magnesium is added to the low concentration of acid?
Slow formation of hydrogen bubbles
Slow change in pH
Most of magnesium ribbon stays solid

What happens when the magnesium is added to the high concentration of acid?
Faster formation of hydrogen bubbles
Faster change in pH
Disappearance of the magnesium ribbon

Why did whatever happened, happen when the magnesium was added to the high and low concentrations of acid?
As the concentration of acid increases, the rate of collisions between the acid ions and metal ions increases
Time it takes for reaction to occur decreases

What color does sodium hydroxide turn in the presence of a universal indicator? What about hydrochloric acid?
Violet and Red

When hydrochloric acid and sodium hydroxide combine, what happens, and what color does it turn?
The mixture becomes neutralized and turns green.