Spilling a chemical is against the ethics of science because the spilled chemical could have large scale deleterious effects of the fauna and flora. Even though the action in itself is unethical in scientific parlance, but the question is clear about the fact that the scientist made a mistake. Hence we can regard his action as an ethical mistake.
The two can be mixed in water, since the salt is soluble it will dissolve and the sand will remain. To separate it from the water use filter paper and a beaker.
