Scientific notation ? Please help

(5.55 x 10^15) x (8.88 x 10^18)

Explanation:

I first take back the numbers to their original forms that is to say (5.55×10^15) = 5550000000000000 and (8.88×10^18) = 8880000000000000000 therefore the difference of the two will be 887445 which is notated to (8.87445×10^5)

(8.87445×10^5)

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.

level 4 to level 2 : ))