The reaction involves the reflux of a mixture containing ethyl acetate and ethyl propanoate with C2H5ONa / C2H5OH. This reaction is known as ester condensation, which results in the formation of a new ester compound. To determine the number of different condensations that would be formed, we need to consider the possible combinations of the two starting esters.

First, let's understand the reaction mechanism involved in ester condensation. The reaction is a nucleophilic acyl substitution, where the alkoxide ion (C2H5O-) acts as a nucleophile and attacks the carbonyl carbon of the ester. This results in the formation of an intermediate alkoxide ester, which then undergoes a proton transfer to form the final ester product.

Now, let's consider the possible combinations of ethyl acetate and ethyl propanoate:

1. Ethyl acetate reacts with ethyl acetate:
- The alkoxide ion attacks the carbonyl carbon of ethyl acetate, resulting in the formation of an intermediate alkoxide ester.
- The alkoxide ester undergoes a proton transfer to form the final ester product.
- This condensation results in the formation of ethyl acetate-ethyl acetate ester.

2. Ethyl propanoate reacts with ethyl propanoate:
- The alkoxide ion attacks the carbonyl carbon of ethyl propanoate, resulting in the formation of an intermediate alkoxide ester.
- The alkoxide ester undergoes a proton transfer to form the final ester product.
- This condensation results in the formation of ethyl propanoate-ethyl propanoate ester.

3. Ethyl acetate reacts with ethyl propanoate:
- The alkoxide ion attacks the carbonyl carbon of ethyl acetate, resulting in the formation of an intermediate alkoxide ester.
- The alkoxide ester undergoes a proton transfer to form the final ester product.
- This condensation results in the formation of ethyl acetate-ethyl propanoate ester.

4. Ethyl propanoate reacts with ethyl acetate:
- The alkoxide ion attacks the carbonyl carbon of ethyl propanoate, resulting in the formation of an intermediate alkoxide ester.
- The alkoxide ester undergoes a proton transfer to form the final ester product.
- This condensation results in the formation of ethyl propanoate-ethyl acetate ester.

5. Ethyl acetate reacts with itself:
- The alkoxide ion attacks the carbonyl carbon of ethyl acetate, resulting in the formation of an intermediate alkoxide ester.
- The alkoxide ester undergoes a proton transfer to form the final ester product.
- This condensation results in the formation of a cyclic ethyl acetate ester.

6. Ethyl propanoate reacts with itself:
- The alkoxide ion attacks the carbonyl carbon of ethyl propanoate, resulting in the formation of an intermediate alkoxide ester.
- The alkoxide ester undergoes a proton transfer to form the final ester product.
- This condensation results in the formation of a cyclic