Carbon monoxide reacts with oxygen to form

carbon dioxide by the following reaction:
2CO(g) + O2(g) ! 2CO2(g)
�H for this reaction is −135.28 kcal.
If 811.7 kcal is released, how many moles of
CO must have reacted?

To determine the number of moles of CO that reacted, we can use the principle of stoichiometry, which relates the mole ratios of substances in a balanced chemical equation. In this case, we have the balanced equation:

2CO(g) + O2(g) → 2CO2(g)

We can see that the balanced equation shows a 1:2 ratio between CO and CO2. For every 2 moles of CO, we get 2 moles of CO2.

We are given the enthalpy change (∆H) for the reaction, and we know that 811.7 kcal is released. We can use the equation:

∆H = q/n

where ∆H is the enthalpy change, q is the amount of heat released or absorbed, and n is the number of moles of reactant or product.

We can rearrange this equation to solve for n:

n = q/∆H

Substituting the given values, we have:

n = 811.7 kcal / (-135.28 kcal)

Calculating this, we get:

n ≈ -6.0 moles

Since moles cannot be negative, we can conclude that approximately 6 moles of CO must have reacted.

See your other post above with heat in kJ/mol.