At constant pressure, the combustion of 5.00 g of c2h6(g) releases 259 kj of heat. what is δh for the reaction given below? 2 c2h6(g) + 7 o2(g) → 4 co2(g) + 6 h2o(l).

3120 kJ

Given:

At constant pressure, the combustion of 5.00 g of C₂H₅  releases 259 kJ of heat.

Question:

What is ΔH for the reaction given below?

.

The Process:

Step-1

Step-2

Let us convert mass to mol of 5 g of C₂H₅.

Remember, the combustion of 0.166 moles of C₂H₅ releases 259 kJ of heat.

Step-3

Combustion reactions that release heat into the environment, including the type of exothermic reaction. The exothermic reaction has a negative ΔH because the product enthalpy is lower than the reactant enthalpy of the system.

And now, we will solve the problem of what is ΔH for the reaction given below.

Notice that 2 moles of C₂H₅ take part in this reaction.

Thus, the combustion of C₂H₅ based on the equation of reaction above releases heat of 3120 kJ.

petroleum? coal maybe?

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !