Revision questions Solutions 1 When salt and water are mixed, they make salt water. Is this a new substance? Explain your answer. 2 When instant coffee is mixed with hot water, identify the: a solute b solvent c solution. 3 Give two examples of solutions not already mentioned in Unit 3.1. 4 Give two examples of substances that are: a soluble in water b insoluble in water. 5 True or false? a In a solution, the solvent is always water. b A solute is always a solid. c A substance that is insoluble must be a solid. 6 In a solution, the particles of the solute cannot be seen because: A they are spread too thinly throughout the solvent B they have been destroyed by the solvent C they have been converted to solvent particles D they reflect light away from you E they have combined with the solvent to form a new substance. 7 What word would you use to describe a: a strong solution with lots of solute? b weak solution containing little solute? 8 You have two glasses of orange cordial. One is concentrated, the other dilute. Which would taste stronger? Suspensions 9 Give an example of a suspension. 10 How could you test if cordial is a suspension or a solution? 11 What do you call the substance that settles out of a suspension? Colloids 12 How could a torch show if you have a colloid or solution? 13 Describe how detergent changes an oil/water suspension into an emulsion. 14 What do we call the substance in which particles are being spread out? 15 Copy and complete the table below for the six different types of colloid: 16.Graffiti remover is used to wash paint from a wall. Is the paint the solvent, solute or solution? 17 Copy and complete: A ________ contains smaller particles than a ________, but bigger particles than a __________, and (will/will not) settle out if left long enough. 18 Classify each of the following as solution, suspension or colloid: glue, saline (salt water), cream, whisky, muddy water, sunscreen. 19 Draw a diagram comparing the particles in a solution, emulsion and suspension. 20 Why is it important that fertilisers be soluble? 21 Why is it very important that some medicines be shaken before being taken? 22 Why are many chemicals more effective in liquid form? Analysis questions 23 Describe how you would make a dilute glass of orange cordial: a more dilute and less concentrated b more concentrated. 24 A lot of people put so much sugar in their cup of tea that sugar is left on the bottom of the cup. a What is the scientific name for this type of solution? b How could you get this sugar to dissolve?