C5-1 Purity and mixtures

In chemistry, what does pure mean?

• Has only one name

• Contains very few contaminants

• Is a liquid at room temperature
• Contains only one type of molecule or atom

How can we tell from the melting point if a substance is pure?

• By using an infrared thermometer

• Th lower the melting point the lower the purity of a substance

• Chemically pure substances melt at a specific temperature

• By looking at the colour of the substance compared to a reference sample

What effect do impurities have on the melting point of a pure substance?

• Raise the melting point
• Lower the melting point
• Have no effect on the melting point
• Cause the substance to solidify at room temperature

What name do we give to substances that contain more than one element or compound which are NOT chemically joined together?

Which of the following is the correct definition for a formulation?

• A specific combination or recipe of ingredients used to create a product or substance
• A type of geological formation
• A type of musical composition
• A type of mathematical equation

In a formulation made from water and oil, the ration of water to oil is 1: 5.

If the total volume of the formulation is 12ml, how much water is present?

• 1ml

• 2ml

• 5ml

• 6ml

In a formulation made from water and a solvent the ration of water to oil is 2: 3.

If the total volume of the formulation is 15ml, how much water is present?

• 1ml

• 2ml

• 5ml

• 6ml

The melting point of benzoic acid is 122'C. The melting point of a sample taken in a laboratory was 120-125'C.

Which TWO reasons why this suggests the sample is NOT pure?

• The melting point is more precise.

• A range is give for the answer.

• The range contains the melting point.

• The range is lower than the melting point.

Which of these is a formulation?

• Many everyday products such as paint

• Small molecule

• musical composition

• mathematical equation

Which of these is NOT a formulation?

• Paint

• Medicine

• Fertiliser

• Carpet