Awebsite promoting the use of alternative energy vehicles and hybrid technologies claims that "a typical automobile in the usa uses about 500 gal of gasoline every year, producing about 5 tons of carbon dioxide."

to determine the truth of this statement, calculate how many tons of carbon dioxide are produced when 500.0 gal of gasoline are combusted. assume that the primary ingredient in gasoline is octane, c8h18(l), which has a density of 0.703 g·ml−1.

i just learnt this recently but i need to look through my notes again

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

i belive it is water