Chemistry Unit 4: Reactions and Stoichiometry

Throughout our unit 4 in Chemistry, we learned about reactions and stoichiometry. In this unit we went over, types of reaction, did some labs and did a few calculation on the reaction rate.

There are five types of reaction: 

1. Synthesis – Two substances react to form a single product.
   1. x+y → xy
2. Decomposition – A single reactant decomposes or breaks down into two or more products
   1. A    →    B + C
3. Combustion – One reactant (fuel) combines with oxygen to produce an oxide and water.
   1. Fuel + O2  →    oxide + H2O
4. Single Replacement – One, more reactive element, replaces another.
   1. M  + AX  →MX + A
5. Double Replacement – A reaction in which the cations and anions of both reactants switch partners.
   1. AX  + DZ    →    AZ + DX

Those are the five types of reaction that can happen to the molecule when they are reacting.  We also went over the reaction rate. A few words that I want to tell are activation energy, activated complex, reactant, and product. 

Activation energy (Ea)  is the minimum amount of energy to start a reaction.

Activated complex is a reaction progresses from reactants to products, it goes through a transition state.

The reactant is a substance in reaction before becoming the product.

A product is as the reaction occurs products is produced.

Reactants → Products

• Start with a concentration of reactants (reagents)  which decrease over time.

• The reaction occurs quickly at the beginning and then slows down.

There are four(4) major factors in looking at the effect in the reaction rate:

2. Concentration-  As the concentration of reactants increases, there are more particles, so more collisions, and the rate will increase.
3. Temperature – As temperature increases, the particles move faster, so more collisions occur, and the rate increases.
4. Surface Area- Reactions take place on the surface of the solid, so as of surface area increase, reaction rate increases. *Notice they are a direct relationship
5. Catalyst- a substance that speeds up a reaction without being consumed

Through this unit, I had understood the difference between reaction rate and reaction time. As well as understanding deeper into looking at the reaction progress of the molecule. This lesson really interests me as a student who doesn’t really interest in Chemistry and I think it is really fun to learn something like this topic.