Chemical Reactions

Question 1

What is the balancing order for chemical equations?

Answer 1

Balancing order:
1. Balance metals
2. Balance non-metals
3. Balance hydrogen atoms
4. Balance oxygen atoms

Question 2

What are the 4 types of chemical reactions?

Answer 2

The 4 types:
1. Composition (A+B → AB)
2. Decomposition (AB → A+B)
3. Single-Displacement (AB + C → CB + A)
4. Double-Displacement (AB + CD → AD + CB)

Question 3

Explain what a ‘Combustion Reaction’ is

Answer 3

A combustion reaction is when a hydrocarbon substance (substance containing hydrogen and carbon) combines with oxygen to form carbon dioxide and water.
(ex. CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g)

Question 4

Explain what a ‘Neutralization Reaction’ is

Answer 4

A neutralization reaction is a type of double-displacement reaction between an acid and a base. This produces water and a salt.
(acid + base → water + salt)
(eg. HCl + NaOH → NaCl + H₂O)
(IMPORTANT: Acids most likely contain H at the start, whilst a base usually contains OH)

Question 5

How do you know if a chemical is an acid or a base IN THIS UNIT?

Answer 5

In this unit:
- Acids are often spotted with hydrogen in their chemical formula (eg. Hydrochloric Acid = HCl)
- Bases are often spotted with hydrogen and oxygen in their chemical formula (eg. Sodium Hydroxide = NaOH)

Question 6

What do I do if I need to determine if a substance is aqueous or a solid?

Answer 6

Look at the Solubility chart. If it is soluble, it is aqueous. If it is insoluble, it is a solid.

Question 7

What is an exothermic reaction?

Answer 7

An exothermic reaction transfers energy into the surroundings, releasing heat and increasing the temperature of its surroundings (eg. Burning of fuel to start a stove)

Question 8

What is an endothermic reaction?

Answer 8

An endothermic reactions absorb energy from the surroundings, absorbing heat and decreasing the temperature of its surroundings (eg. Plants utilizing sunlight for photosynthesis).

Question 9

What does the collision theory state?

Answer 9

The collision theory states that reacting particles need to collide with sufficient energy and the right orientation in order to break bonds and react.

Question 10

What are the first 2 methods you can do to increase the reaction rate (the rate the reactants form into products)?

Answer 10

First 2 methods:
1. Increasing the surface area of solids to allow more collisions (eg. chopping up wood)
2. Increasing the concentration of reactants in a solution, as more particles leads to more collisions, and therefore, more reactions.

Question 11

What are the last 3 methods you can do to increase the reaction rate (the rate the reactants form into products)?

Answer 11

Last 3 methods:
3. Increasing the temperature to provide more energy for the particles to move around and collide with each other.
4. Increasing the agitation by stirring the particles in a solution, as it keeps the particles in motion for collision.
5. Adding a catalyst, as a catalyst is a substance that facilitates the production of more effective collisions, increasing reaction rate.