enthalpy gaps

Question 1

bond enthalpies are always positive because..

Answer 1

energy is going into the chemical system to break the bonds.

Question 2

average bond enthalpy

Answer 2

the energy required to break 1 mol of a specific type of bond in a gaseous molecule.

Question 3

considerations with average bond enthalpy?

Answer 3

1 mol of a bond in gaseous molecules

Question 4

Enthalpy of formation…

Answer 4

formation of one mol of a substance from its elements.

Question 5

Enthalpy change of reaction

Answer 5

enthalpy change that accompanies a reaction in the molar quantities shown in the equations. under standard conditions, all reactants in their standard states.

Question 6

why is experimental value different to data book value for enthalpy of combustion?

Answer 6

• incomplete combustion occurred,
• non standard conditions
• heat energy lost to surroundings

Question 7

enthalpy change of reaction

Answer 7

the enthalpy that accompanies a reaction in the molar quantities shown in the chemical equation.

Question 8

to calculate energy (joules)

Answer 8

temp change x specific heat capacity x mass