Energetics

Question 1

What are the standard conditions for enthalpy change?

Answer 1

-100kPa
-298K

Question 2

What is an exothermic reaction?

Answer 2

-Give out energy to surroundings
-Products end up with less energy than reactants
-Enthalpy change is negative

Question 3

What is an endothermic reaction?

Answer 3

-Takes in energy from surroundings
-Products end up with more energy than reactants
-Enthalpy change is positive

Question 4

What is bond enthalpy?

Answer 4

-The energy needed to break a bond

Question 5

Is bond breaking endothermic or exothermic?

Answer 5

-Endothermic

Question 6

What is standard enthalpy change of formation?

Answer 6

-The enthalpy change when 1 mole of a compound is formed from its elements in their standard states, under standard conditions

Question 7

What is the standard enthalpy change of combustion?

Answer 7

-The enthalpy change when 1 mole of a substance is completely burned in oxygen under standard conditions, with all reactants and products in their standard states

Question 8

What is the standard enthalpy change of reaction?

Answer 8

-The enthalpy change when a reaction occurs in the molar quantities shown in the chemical equation, under standard conditions with all reactants and products in their standard states

Question 9

What is the equation to calculate enthalpy change?

Answer 9

q=mc_T
q=heat lost of gained (J)
m=mass (g)
c=specific heat capacity
_T=temperature change

Question 10

What is Hess’s law?

Answer 10

-The total enthalpy change for a reaction is independent of the route taken