A student conducts an experiment to determine the speed of a toy car at the bottom of a ramp after it is released from different heights on the ramp. The student makes one measurement for each height
What is one way that the student could improve the experiment?

A. perform one trial for each measurement but use a different car for each height
B. perform multiple trials for each release height instead of just one
C. use a different timer for height
D. use a different ramp for each height

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.

the answer is true.