Chemical Reactions and Stoichiometry

Question 1

What are chemical reactions

Answer 1

The process by which reactants are chemically converted into products.

Question 2

What is involved in a chemical reaction?

Answer 2

Breaking of bonds and the formation of new bonds.

Question 3

What is synthesis?

Answer 3

Producing a larger molecule out of multiple smaller molecules.

Question 4

What is decomposition?

Answer 4

Breaking of a large molecule into multiple smaller molecules.

Question 5

What is single replacement?

Answer 5

When an element is substituted into a molecule for another.

Question 6

What is double replacement?

Answer 6

When the reactants break up and swap places twice.

Question 7

What is precipitation?

Answer 7

A double replacement reaction that results in the production of an insoluble solid.

Question 8

What is combustion?

Answer 8

The reaction of a substance with oxygen in the presence of heat to form oxides.

Question 9

What is oxidation-reduction?

Answer 9

A reaction that involves the transfer of electrons from one reactant to the other to form products.

Question 10

What is hydrolysis?

Answer 10

A reaction of a substance with water.

Question 11

What is neutralisation?

Answer 11

The reaction of an acid with a base to form a salt.

Question 12

What is condensation?

Answer 12

A reaction that involves the production of a new substance and water.

Question 13

What is a word equation?

Answer 13

A chemical equation where the reactants and products are written as words.

Question 14

What is a symbol equation?

Answer 14

A chemical equation where the reactants and products are written as their ionic or molecular formulae.

Question 15

What is an ionic equation?

Answer 15

A chemical equation where the cations and anions that are in the same state in the reactants as they are in the products are omitted.

Question 16

What is the law of conservation of mass?

Answer 16

During a chemical reaction, atoms cannot be created or destroyed.

Question 17

What is balancing chemical equations?

Answer 17

The process of ensuring the number of atoms of each element are the same on each side of a chemical reaction.

Question 18

What is enthalpy?

Answer 18

The total energy of a chemical system.

Question 19

What is the law of conservation of energy?

Answer 19

Energy in a chemical reaction cannot be created or destroyed but changed into different forms.

Question 20

What is chemical potential energy?

Answer 20

The energy stored within the bonds of a substance.

Question 21

What is chemical kinetic energy?

Answer 21

The energy that is due to particle motion.

Question 22

How can the change in enthalpy of a chemical reaction be determined.

Answer 22

▲H = H of products - H of reactants

Question 23

What is an endothermic process?

Answer 23

When energy is absorbed breaking bonds.

Question 24

What is an exothermic process?

Answer 24

When energy is released forming bonds.

Question 25

If the total energy required to break bonds in the reactants is more than the total energy released when new bonds are formed in the products, it is...

Answer 25

an endothermic reaction.

Question 26

The change in enthalpy of an endothermic reaction is...

Answer 26

positive.

Question 27

If the total energy required to break bonds in the reactants is less than the total energy released when new bonds are formed in the products, it is...

Answer 27

an exothermic reaction.

Question 28

The change in enthalpy of an exothermic reaction is...

Answer 28

negative.

Question 29

What is a thermochemical equation?

Answer 29

A chemical equation that shows the energy absorbed or released.

Question 30

Is it an endothermic or exothermic reaction? | 2H2(g) + O2(g) -> 2H2O(l) ΔH = -522kJ

Answer 30

Exothermic reaction.

Question 31

Is it an endothermic or exothermic reaction? | 2H2(g) + O2(g) -> 2H2O(l) + 522kJ

Answer 31

Exothermic reaction.

Question 32

Is it an endothermic or exothermic reaction? | CO2(g) -> C(s) + O2(g) ΔH = +394kJ

Answer 32

Endothermic reaction.

Question 33

Is it an endothermic or exothermic reaction? | CO2(g) + 394kJ -> C(s) + O2(g)

Answer 33

Endothermic reaction.

Question 34

What is formula mass?

Answer 34

The total sum of the atomic masses.

Question 35

How can formula mass be calculated?

Answer 35

Adding up the atomic masses of the elements involved.

Question 36

What is the unit for formula mass?

Answer 36

gmol^-1

Question 37

How do you calculate the % elemental composition?

Answer 37

=Atomic mass of element * number of atoms in substance/formula mass of compound