2. Before we move on, We have… Representing the video clips available
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6. When a substance dissolves in a solvent, it is soluble in that solvent. Water is known as the universal solvent as many substances can dissolve in it. Aqueous solution is thus a solution which has water as the solvent. Nature of solutions When a solution is formed, solute particles are evenly and completely mixed with the solvent particles. evenly mixed Can solutions be separated by physical methods? solvent solute Alcoholic drinks
7. Homogeneous (solution) = physical (e.g. colour) and chemical properties are the same in every part The solute does not settle to the bottom or float to the top when the iodine in alcohol solution is left to stand Light passes through the solution when light is shone through it. Reason : The tiny solute particles are too small to block any light passing through the solution. Filtration cannot be used to separate solutes from its solvent. Reason : The tiny solute particles can pass through the filter paper.
8. 8.2 Suspensions A suspension = mixture containing insoluble solid particles suspended in a liquid A suspension can also consist of liquid droplets or fine solids in a gas Some example of suspensions chalk dust and water calamine lotion hazy environment medicine Nature of suspensions When a suspension is formed, solute particles remain as large visible insoluble solid particles
9. Heterogeneous (suspension) = physical (e.g. colour) and chemical properties are different in every part The insoluble particles will settle to the bottom or float to the top when the suspension is left to stand Light cannot pass through the suspension when light is shone through it Reason : large insoluble particles are large enough to prevent light passing through the suspension Filtration can be used to separate solute from its solvent and the residue collected is the solute Reason : The insoluble particles are too large to pass through the filter paper
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12. Applications at Home and in the Industry Many substances that we use are in the form of solutes, solvents and solutions. Hence, it is important to know about factors affecting the solubility and rate of dissolving of substances At home : washing machine uses hot water and rotating drum to increase the solubility and rate of dissolving of detergent in water In fizzy drinks industry : Temperature of water, Solubility and rate of dissolving extracts BUT, Temperature of water, Solubility and rate of dissolving of carbon dioxide gas So how do we increase the solubility and rate of dissolving of the extracts and gas at the same time?
13. 8.5 Acids and Alkalis acid alkali Acids and alkalis are two common types of aqueous solutions we use every day. Acids Acids can be found all around us: Citrus fruits Contains: Citric acid Tea Contains: Tannic acid Stomach secretions Contains: Hydrochloric acid
