The combustion of pentane, c5h12, occurs via the reaction c5h12(g)+8o2(g)→5co2(g)+6h2o(g) with heat of formation values given by the following table: substance δh∘f (kj/mol) c5h12 (g) -119.9 co2(g) −393.5 h2o(g) −241.8 calculate the enthalpy for the combustion of pentane. express your answer to four significant figures and include the appropriate units.

 -3298.4 kJ/mol

Explanation:

The balanced chemical reaction is,

The expression for enthalpy change is,

where,

n = number of moles

(as heat of formation of substances in their standard state is zero

Now put all the given values in this expression, we get

Therefore, the enthalpy change for this reaction is, -3298 kJ/mol

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

the answer your looking for is c).