In^1H NMR, the intensity of a peak is directly proportional to the number of hydrogen atoms that signal represents. Thus, by integrating each peak to obtain the total area, we can gain information on the relative number of equivalent hydrogen atoms present in a molecule. Label each atom of ethyl acetate with the number of equivalent hydrogen atoms attached to it. If your molecule contains a stereocenter, it is possible that two hydrogen atoms on the same carbon atom are not equivalent. To determine this, we perform a "replacement test". As a thought experiment, replace one of the two hydrogen atoms of interest with something else (you can use the letter X, a square, a triangle, a picture of your dog...it doesn't matter) and draw that compound. Do the same thing with the other hydrogen atom, using the same symbol. Now, compare the two compounds, if these two compounds are the same or if they are enantiomers, these hydrogen atoms will be equivalent by NMR. If the two compounds are diastereomers, these hydrogen atoms will NOT be equivalent, and will have different chemical shifts! (Sometimes this difference in shift is very small and difficult to distinguish. Other times, though, this difference in shift can be as large as 1 or 1.5 ppm apart! This is largely substrate specific, and can be difficult to predict in advance.) Thus, we would expect to see 5 peaks in our^1H NMR spectrum with integrals of 3, 1, 1, 1, and 3.