methods of separating + purifying substances ×× mixtures

Question 1

describe the differences between a pure substance and a mixture

Answer 1

pure substance consists only of one element or one compound. a mixture consists of two or more different substances, not chemically joined together

Question 2

how can you use melting point information to decide whether a substance is pure or is a mixture ?

Answer 2

an impure substance is a type of mixture, so melting points can be used to find out if a substance is pure or impure. Impure substances tend to have a slightly lower melting point than the pure substance, and a broader melting temperature range.

Question 3

describe what happens to atoms at a pure substance’s melting point

Answer 3

the temperature stays the same.

Question 4

explain why the temperature does not change as a pure substance melts.

Answer 4

the heat is used to break the bonds between the ice molecules as they turn into a liquid phase