Calculate delta h in kj for the following reactions using heats of formation:
a) 2c2h6 (g) + 7o2 (g) > 4co2 (g) +6h2o (g)

b) 2pbo (s) + pbo2 (s) > pb3o4 (s)

per mole reaction.

per mole reaction.

Explanation:

What is the standard enthalpy of formation of a substance? the enthalpy change when one mole of the substance is formed from the most stable allotrope of its elements under standard conditions.

Naturally, for the most stable allotrope of each element under standard conditions. For example, oxygen (not ozone ) is the most stable allotrope of oxygen. Also, under STP  is a gas. Forming from itself does not involve any chemical or physical change. As a result, for .

Look up standard enthalpy of formation data for the rest of the species. In case one or more values are not available from your school, here are the published ones. Note the state symbols of the compounds (water/steam in particular) and the sign of the enthalpy changes.

How to calculate the enthalpy change of a reaction (or simply from enthalpies of formation?

For the first reaction:

Try these steps for the second reaction:

.

there all right good

explanation:

let that person have a turn to speak : )