Student Polyester wants to synthesize triphenylmethanol by a condensation reaction between a ketone (benzophenone) and a Grignard reagent (phenylmagnesium bromide). Carefully she cleaned the 1.0-mL syringe with H2O just before the addition of the ethereal solution of benzophenone to the phenylmagnesium bromide. The syringe was not properly dried and had a copious quantity of H2O in it during the transfer of the ethereal benzophenone solution to the freshly prepared Grignard reagent. 1. Predict all three products of this experiment.
2. Why is it important that all the equipment used in the Grignard formation be completely dry?
3. Name the major undesired side-product formed in the Grignard reaction in this experiment in the absence of water.
4. You will perform the same experiment as Polyester following your handout procedure.
a. What is the purpose of adding hexane to the crude product obtained after evaporation of the ether?
b. What product would be formed if acetone were added to the Grignard reagent instead of benzophenone?
c. If you had leftover benzophenone in your sample, how would the product melting point be affected?
d. How can the IR spectrum be used to tell whether any leftover benzophenone was present in your product sample?

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.

3

explanation:

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.