Please Help! Your car has 1.95 gallons of gasoline (octane, d = 0.6916 g/mL), which reacts with oxygen
according to the balanced reaction below. Your car uses the energy produced by this reaction
at a rate of 115 kJ per second while traveling at a speed of 65 miles per hour. Calculate the
distance (in miles) the car can travel using this amount of octane.
2 C8H18(g) + 25 O2(g) > 16 CO2(g) + 18 H2O(g) ΔHrxn = -10,900 kJ

38.3 miles

Explanation:

First, we convert 1.95 gallons to mililiters:

Then we calculate how many grams of octane are available for the reaction, using its density:

Now we convert octane grams into octane moles, using its molar mass:

Then we calculate how many kJ are produced from the combustion of  44.78 mol C₈H₁₈, if 2 moles produce 10900 kJ:

We calculate how many seconds is the car available to keep going, if it spends 115 kJ per second:

We convert seconds to hours:

Finally we calculate the distance:

- aluminum and copper chloride.

- the chloride ion to separate the aluminum from the oxygen so that the aluminum can react with the copper ions (and the water molecules).

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.