Chemistry chapter 4

Define Synthesis:

Building up of compounds by combining simpler substances (e.g. elements) - A+B = AB

What does this general equation help to determine: A+B = AB?

What will be produced in a synthesis equation

What does the position of subscripts mean in a chemical formula?

Bottom = number of atoms

Top = charge/ mass number

How do you check if a chemical equation follows the law of conservation of mass?

Count the numbers of atoms on both sides. Make sure no atoms are made/ destroyed.

What are decomposition reactions?

The breakdown of compounds into simpler substances.

What energy do all reactions often require?

heat & electricity.

Define electrolytic decomposition:

The breakdown of a compound due to an electric current passing through a solution.

what is an electrical component?

A device in a circuit that controls, stores, or uses electric energy

What is a diode in electrolysis?

An electrical component that allows current flow in only 1 direction.

What are 2 diodes used in electrolysis?

Anode (+) and Cathode (-). Each one causes a different chemical reaction.

Why are electrolysis reaction endothermic?

Because they absorb energy for the reaction to occur.

What do fertilizers do?

Neutralize acidic soils (e.g. Calcium oxide)

What’s the difference between a concentrated acid and a strong acid?

Concentrated = how much acid is present. (more acid, less water)
Strong = how easily it reacts. (easily gives away hydrogen ions)

What is a base?

Substances that gain hydrogen ions.

What is the difference between soluble and insoluble?

Soluble- It can dissolve in a liquid.
Insoluble - unable to dissolve in liquid

What is a precipitation reaction?

Reaction where two solutions form an insoluble solid

What are spectator ions?

Ions that don’t change or react — they just “watch.”

In a double displacement compound which ion is written first?

The positive ion is always written first.

What is a double displacement reaction?

A reaction where two compounds swap ions, forming new substances.

What do solubility rules say always dissolves in water?

• Group 1

• ammonium salts

• nitrate salts

What can you use to predict whether a precipitate will form?

by using solubility rules

When does an Oxidation reaction occur?

When an element reacts with oxygen.

What is formed when a metal undergoes an oxidation reaction?

Metal oxide

What energy is produced when non-metals combust with oxygen?

Heat and light.

What are the products of hydrocarbon combustion?

Carbon dioxide and water.

What is an exothermic reaction?

Reaction that releases heat and light (explosive)

What group doesn’t react with oxygen?

Group 18

What is a combustion reaction?

When a substance burns in oxygen and gives off heat and light.

What is the collision theory?

Reactants must collide in the correct orientation for a reaction to occur

What must happen for hydrogen iodide molecules to react?

Hydrogen iodides must collide

How can you increase the number of collisions occurring?

By increasing the:
- Surface area of particles reacting
- concentration of the reactants
- temperature of the reaction.

Define catalyst

A substance that speeds up a chemical reaction but doesn’t get used up in the reaction.

What is an enzyme?

A catalyst made and used in living cells.

What is ionic bonding?

Metal + Non-metal

What is covalent bonding?

Non-metal + Non-metal

What is produced when an acid and a base (neutralization) form a reaction?

Salt and water

Why is it unsuitable to store acids in metal containers?

Acids react with metals. This would corrode the metal and the acid would leak out of the container.

Would it require more, less or the same amount of base to neutralize 20 mL of 0.1 M strong acid than it would to neutralize 20 mL of 0.1 M weak acid?

same volume as both have the same concentration. Concentration determines the amount of base it would take to neutralize each acid, not the strength of the acid.

Which of the following substances would be insoluble?

Group 2

Transition metals

Lead and silver

What are the differences between a linear polymer and a cross-linked polymer?

Linear polymers are long chains, sometimes with side branches.

Cross-linked polymers are networks where chains are connected in multiple directions.

What are the properties of elastomers?

Stretchy materials made of linked polymers.

Why does increasing the surface area increase the rate of reaction?

The larger the surface of a reactant, the more of the chemical that can react.

Why does diluting a solution decrease the rate of reaction?

Dilution decreases the concentration

What do acids + carbonates form?

water + salt + carbon dioxide

What do acids + metals form?

Salt + hydrogen