ethyl chloride (c2h5cl) can be used as a topical anesthetic, for example prior to giving a painful injection. when liquid ethyl chloride is sprayed on the skin, energy absorbed from the skin causes the liquid to evaporate. this numbs the injection site by quickly decreasing the skin temperature to near 0oc. how much heat (in kj) is required to evaporate 8.21 ml of ethyl chloride at 25oc?
