Answer:
(B.) and (C.)
b. So that clean NMR spectra can be obtained that do not contain solvent peaks.
c. So that the yield can be determined.
Explanation:
The solvent used in Nuclear Magnetic Resonance (NMR) spectrometer is Trimethyl silane (TMS), a neutral solvent which doesn't give off any signals. Other solvents could have interactions with the radiation, and disrupt the spectra.
Furthermore, for accurate determination of the actual yield and overall percentage yield, solid must be separated from the solvent, dried and weighed.
I hope this was explanatory enough.
Identity and chemical properties
A. -20kj
Explanation:
The reaction is exothermic
therefore enthalpy = 20 - 40 = -20
