FUNCHEM 25: Driving Forces Behind Chemical and Biological Reactions

What does thermodynamics and spontaneous reactions mean?

Thermodynamics- tool used to predict whether a reaction is spontaneous or not

Spontaneous reaction: occur of their own accord

What are the driving forces behind chemical and biological reactions?

Enthalpy and Entropy

What is the symbol and unit of Enthalpy

H and kJ mol^-1

In energy profile diagram would the arrow go up or down for exothermic and endothermic reactions

Down for exothermic

Up for Endothermic

What is Standard Enthalpy Change

Enthalpy change art temperature of 298K and 1atm pressure

What are the different types of enthalpy change? and Explain

Standard Enthalpy Change of Formation- is the enthalpy change that occurs when 1 mole of a compound is formed from its uncombined elements at 298K and 1 atm pressure

Standard Enthalpy Change of Combustion- is the enthalpy change that occurs when 1 mole of an element or compound has been burned in excess oxygen at 298 K at 1 atm

Standard Enthalpy Change of Reaction

What is the first law of thermodynamics

Energy cannot be created or destroyed, it can only be converted from one form to another

What does Hess’s law state?

Hess’s Law states that the enthalpy change. of a reaction is the same regardless of the pathway by which a reaction occurs.

What are the rules for thermochemical reactions?

1. Must have balanced reactions

2. Must specify the states of the reactants and products

3. Reverse reaction= reverse sign

4. DH depends on the amount reacting

5. Enthalpy of formation of an element in its most stable form

Determine the molar heat of combustion of methanol