CHEMICAL REACTIONS

Question 1

Describe the changes that occur as a part of a chemical reaction

Answer 1

color change
formation of a precipitate
formation of a gas
odor change
temperature change

Question 2

What are the standard aspects of a chemical equation?

Answer 2

• Reactants on the left hand side and products on the right
• Physical states denoted as subscripts in brackets
• The delta sign can be placed above the arrow in between products and reactants if reactants are heated

Question 3

How to balance a chemical equation

Answer 3

1. Write out the unbalanced equation with all molecules or atoms involved
2. Count out the number of each atom either side, apply coefficients as necessary until they are the same either side
3. include the states as subscripts

Question 4

Describe conservation of mass in terms of atoms

Answer 4

No atom is created or destroyed in a chemical reaction therefore, once a reaction has taken place, the total mass of the reactants should equal the total mass of the products

Question 5

What is a combination reaction?

Answer 5

Two or more reactants combine to yield a single product

Question 6

What is a decomposition reaction?

Answer 6

1 reactant splits into 2 or more products

Question 7

What is a single replacement reaction?

Answer 7

One element replaces another element in a molecule

Question 8

What is a double replacement?

Answer 8

Two elements replace each other in molecules

Question 9

What is a combustion reaction?

Answer 9

Carbon compound burns in oxygen gas to form CO2 and H2O, energy is released as a product in the form of heat

Question 10

What is a polymerisation reaction?

Answer 10

Molecules join to form a long chain

Question 11

What is a redox/oxidation-reduction reaction?

Answer 11

Electrons are transferred from 1 substance to another, oxidation is the loss of electrons, reduction is the gaining of electrons

Question 12

Describe exo and endothermic reactions

Answer 12

Exothermic: energy is transferred from system to surrounding

Endothermic: energy is transferred from the surrounding to the system