Final answer:
If the impurity in the liquid product is leftover benzaldehyde, then the liquid product is not pure. The presence of specific IR peaks can be used to determine the existence of benzaldehyde impurity in the liquid product.
Step-by-step explanation:
If the impurity in the liquid product is leftover benzaldehyde, then the liquid product is not pure. Benzaldehyde is a known impurity that can be present in the liquid product. To determine whether the liquid product is pure or not, we can analyze its infrared (IR) spectrum for specific peaks that are characteristic of benzaldehyde.
One key IR peak to look for is the aldehyde C=O stretch, which typically occurs around 1700-1750 cm-1. If this peak is present in the IR spectrum of the liquid product, it indicates the presence of benzaldehyde impurity.
Another key IR peak to consider is the aromatic C-H stretch, which is usually observed as a series of peaks around 3000-3100 cm-1. If these peaks are present, it suggests the presence of an aromatic compound, such as benzaldehyde.