Energetics Flashcards
State what s meant by enthalpy
The energy content of a substance measured at constant pressure
Exothermic reactions have a positive or negative enthalpy change?
Negative
State what is meant by enthalpy change of formation
The enthalpy change when one mole of a substance is made from its constituent elements with all products and reactants in their standard states under standard conditions
State what is meant by enthalpy change of combustion
The enthalpy change when one mole of a substance is burned completely in oxygen with all reactants and products in their standard states under standard conditions
How do you work out enthalpy?
q/mol
State what is meant by specific heat capacity
The energy needed to raise the temp. of 1g of a substance by 1*C
What is the equation to work out energy from specific heat capacity?
q = m x c x ^T energy = mass x specific heat x temp.change
State what is meant by mean bond enthalpy
The average heat needed when one mole of covalent bonds are broken measured in the gaseous state at 298K and 100kPa
What does Hess’s law state?
Enthalpy change for reactions is the same regardless of the rate or route taken
