Chemistry Exam Question- Unit 2

Explain why mixtures melt over a range of temperatures but pure substances have a precise melting point

Explain the difference between a risk and a hazard

Two dyes have the same Rf values when tested using chromatography. Explain whether this means they are the same dye or not.

A student is asked to separate two liquids. Liquid A boils at 100 degrees and liquid B boils at 65 degrees. The student sets up a fractional distillation experiment, and after a few minutes a clear liquid is collected from the condenser. Explain which of the two liquids will be collected first.

Fresh water is treated to make it safe to drink. Soluble and insoluble substances are removed during this treatment, and chlorine is added to kill harmful microorganisms. State two reasons why samples of the treated water are tested regularly.