Some databases allow you to search by physical properties (specific values as well as ranges or greater and less than) to identify potential substances that match your criteria. However, they are only as good as the substances and properties they cover, the search interface and features, and the quality and quality of property data points you enter. You will likely need to cross-search with one or more additional properties if you get too many results. When working with an unknown for a course like CHEM 143C, you may be better off narrowing down to a list of potential compounds and then searching for these compounds to see if the property data confirms what you observed in the lab.