Unit 2

• Dissolving is a process where a solute is mixed with a solvent to form a solution.
• All solutions are transparent.
• The law of conservation of mass states that the total mass of a system remains constant during changes within the system.
• In a solution of sugar and water, sugar is the solute and water is the solvent
• Dissolving is different from melting in that melting is a phase change where a solid changes to a liquid.
• The mass of salt solution made when 9g of salt is dissolved in 50g of water is 59g.
• A green powder placed into a beaker of water forms a solution when stirred.
• When measuring the volume of a liquid, it is important to use the same measuring device each time to ensure accuracy.
• Solutions can be made of different concentrations, compared, and their solubility investigated.
• A saturated solution is one where no more solute can be dissolved.
• The amount of copper sulfate that will dissolve in 100 g of water at 20 °C is 1.2 g.
• The amount of potassium chlorate that will dissolve in 200 g of water at 20 °C is 2.2 g.
• The amount of sodium chloride that will dissolve in 50 g of water at 20 °C is 4.2 g.
• The solubility of various solutes can be compared by drawing a bar chart showing the amount of each solute that will dissolve in 100 g of water at 20 °C.
• The volume of water does not affect the results of a solubility investigation if it is kept the same each time.
• The independent variable in a solubility investigation is the concentration of the solution, while the control variable is the volume of water.
• The dependant variable in a solubility investigation is the amount of solute that will dissolve in a given volume of water.
• Paper chromatography is used to separate dissolved substances.
• Chromatograms can be interpreted to determine the identity of the substances separated.
• Scientific language should be used accurately in all written and spoken communication.
• Food dyes are pure substances, with the exception of Red 40, which is not a pure substance.
• The most soluble coloured substance in food dyes is Red 3, while the least soluble is Red 40.
• The chromatogram for Sunny Red shows four separate substances, with Red 3 being the most soluble and Red 40 being the least soluble.
• The scientist decides to run the test again because Red 40 is the least soluble.
• The most soluble substance in Sunny Red is Red 3.
• A solution is a mixture of solute and solvent
• All solutions are transparent
• Law of conservation of mass
• In a solution of sugar and water, water is the solvent and sugar is the solute
• Dissolving is different from melting
• When 9g of salt is dissolved in 50g of water, the mass of the salt solution is 59g
• A solution is not formed when a green powder placed in water looks cloudy and lumps of powder can still be seen
• To measure the volume of a liquid accurately, ensure to read the meniscus at eye level
• A saturated solution is one where no more solute can dissolve in the solvent
• Paper chromatography is used to separate dissolved substances