Complete the following sentences:

a In an exothermic reaction, the energy transferred to the surroundings from forming new bonds is than the energy needed to break existing bonds.

b In an endothermic reaction, the energy transferred to the surroundings from forming new bonds is than the energy needed to break existing bonds.

c The energy change of an exothermic reaction has a sign.

d The energy change of an endothermic reaction has a sign.

Explanation:

a) In an exothermic reaction, the energy transferred to the surroundings from forming new bonds is ___more than the energy needed to break existing bonds.  

b) In an endothermic reaction, the energy transferred to the surroundings from forming new bonds is ___less than the energy needed to break existing bonds.  

c) The energy change of an exothermic reaction has a negative sign.  

d) The energy change of an endothermic reaction has a positive sign.

The energy changes occur during the bonds formation and bonds breaking.

There are two types of reaction endothermic and exothermic reaction.

Endothermic reactions:

The type of reactions in which energy is absorbed are called endothermic reactions.

In this type of reaction energy needed to break the bond are higher than the energy released during bond formation.

For example:

C + H₂O   →  CO  + H₂

ΔH = +131 kj/mol

it can be written as,

C +  H₂O  + 131 kj/mol  →  CO  + H₂

Exothermic reaction:

The type of reactions in which energy is released are called exothermic reactions.

In this type of reaction energy needed to break the bonds are less than the energy released during the bond formation.

For example:

Chemical equation:

C + O₂   →  CO₂

ΔH = -393 Kj/mol

it can be written as,

C + O₂   →  CO₂ + 393 Kj/mol

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.