Question

The presence of an impurity can affect the observed melting point of a sample in two different ways: certain impurities can have only one, only the other, or both effects depending on what the impurity is and how much is present. What are the two effects (that is, how would the observed melting range change compared to the literature value of the pure substance)?

a.

b.

One measures the amounts of lots of chemicals in a reaction, including those that act as “reactant”, “catalyst”, “solvent”, and “product”.

a. Which one(s) of these are relevant for determining the theoretical yield of a reaction?

b. Which of the chemicals that you plan to add to the dulcin reaction would be classified as “reactant”?

Draw a plausible covalent structure for isocyanic acid. Make sure you include all lone-pairs and bonds explicitly.

Assuming you perform the dulcin experiment using the exact amounts of chemicals given in the procedures, what is the total volume of water that is used for the reaction itself? You may wish to examine the procedures step by step to determine at which point "the reaction" (the physical and chemical changes leading to the formation of the dulcin molecules) has finished so that you do not accidentally confuse the actual synthesis of the product with later steps that merely serve to purify or extract the product once it has already formed.

Answer 1