A solution of citric acid (H₃C₆H₅O₇) with a known concentration of 0.200 M H₃C₆H₅O₇ is titrated with a 0.750 M NaOH solution. How many mL of NaOH are required to reach the third equivalence point with a starting volume of 25.0 mL H₃C₆H₅O₇ , according to the following balanced chemical equation: H₃C₆H₅O₇ + 3 NaOH → Na₃C₆H₅O₇ + 3 H₂O

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.

a pan containing water is placed in a positio n where it is exposed to a 10 mile per hour wind. the pan contains a uniform depth of 1.27 cm of water, is quite wide, and has a length of 2.44 m in the wind direction. the water in the pan is at a constant temperature of 15.5 °c.