Solutions

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Solutions, solubility, concentrations, acids and bases

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  • 1. SCI 409 Marni Hamili B. Dieron Mary Amor T. Dorado

2. SOLUTIONS a homogenous mixture of particles. made up of solute (lesser amount; dissolved medium) and solvent (greater amount; dissolving medium) 3. KINDS OF SOLUTIONS: 1.Solid Solutions 4. KINDS OF SOLUTIONS: 2. Liquid Solutions 5. KINDS OF SOLUTIONS: 3. Gaseous Solutions 6. SOLUBILITY - maximum amount of solute dissolved by a given amount of solvent at a definite temperature - a measure of the maximum amount of solute that can be dissolved in a given amount of solvent to form a stable solution 7. TYPES OF SOLUTIONS 1. SaturatedSolution- holds the maximum amount of solute 2. UnsaturatedSolution - holds less than the maximum amount of solute 3. SupersaturatedSolution - holds more than the maximum amount of solute 8. FACTORS AFFECTING SOLUBILITY The larger the molecules of the solute are, the larger is their molecular weight and their size. It is more difficult for solvent molecules to surround bigger molecules. If all of the above mentioned factors ale excluded, a general rule can be found that larger particles are generally less soluble 9. FACTORS AFFECTING SOLUBILITY Substances with similar intermolecular attractive forces tend to be soluble in one another. This generalization is stated as "like dissolves like." 10. FACTORS AFFECTING SOLUBILITY Liquids that are attracted by charged objects are composed of polar molecules; those that are not attracted by a charged body are non polar. 11. FACTORS AFFECTING SOLUBILITY Non polar solutes are soluble in non polar solvents; Polar or ionic solutes are soluble in polar solvents 12. FACTORS AFFECTING SOLUBILITY In endothermic process (heat is absorbed) solubility increases with the increase in temperature and vice versa. For example: solubility of potassium nitrate increases with the increase in temperature. 13. FACTORS AFFECTING SOLUBILITY In exothermic process (heat is released) solubility decrease with the increase in temperature. For example:solubility of calcium oxide decreases with the increase in temperature. *Gases are more soluble in cold solvent than in hot solvent. 14. THE MOLE CONCEPT 15. Concepts of mole: 1.Avogadros number 2.Molar mass 3.Molar volume 16. - a unit for counting the number of particles - 6.02 1023 particles (602, 000, 000, 000, 000, 000, 000, 000) 1 mole of oxygen atoms consists of 6.02 1023 atoms O. 1 mole of chlorine atoms consists of 6.02 1023 Cl. 1 mole of hydrochloric molecules consists of 6.02 1023 HCl. 1 mole of sodium chloride molecules consists of 6.02 1023 NaCl. 17. - a mole of atoms of any element will have a mass in grams numerically equivalent to the elements atomic number; a mole of molecules of any compound, will have a mass in grams numerically equivalent to the compounds formula mass or molecular mass. n Molar mass is a mole of any substance in grams. 18. 1 mole O atom has a mass of 16 grams. 1 mole Cl atom has a mass of 35 grams. 1 mole HCl molecules has a mass of 36 grams 1 mole NaCl molecules has a mass of 58 grams. 19. - mole of any gas in an enclosed container, it will occupy a volume of 22.4 litres at standard temperature and pressure or STP (STP is 0oC and 1 atm). 20. 1 mole H2 gas occupies a volume of 22.4 litres at STP. 1 mole He gas occupies a volume of 22.4 litres at STP. 1 mole Cl2 gas occupies a volume of 22.4 litres at STP. 1 mole O2 gas occupies a volume of 22.4 litres at STP 21. CONCENTRATIONS OF SOLUTIONS - refers to the mass or volume of solute present in a specified amount of solvent. 22. This is the mass of the solute divided by the mass of the solution (mass of solute plus mass of solvent), multiplied by 100. Example: Determine the percent composition by mass of a 100 g salt solution which contains 20 g salt. Solution: 20 g NaCl / 100 g solution x 100 = 20% NaCl solution 23. Volume percent or volume/volume percent most often is used when preparing solutions of liquids. Volume percent is defined as: v/v % = [(volume of solute)/(volume of solution)]x100% 24. Example: Wine is about 12% v/v ethanol. This means there are 12 ml ethanol for every 100 ml of wine. It is important to realize liquid and gas volumes are not necessarily additive. If you mix 12 ml of ethanol and 100 ml of wine, you will get less than 112 ml of solution. 25. Example: 70% v/v rubbing alcohol may be prepared by taking 700 ml of isopropyl alcohol and adding sufficient water to obtain 1000 ml of solution (which will not be 300 ml). 26. Molarity is probably the most commonly used unit of concentration. It is the number of moles of solute per liter of solution (not necessarily the same as the volume of solvent!). 27. Example: What is the molarity of a solution that contains 10.0g of HCl (molar mass 36.5g/mol) per liter of solution? Solution: First we find the number of moles of HCl equivalent to 10.0g of HCl. 10.0g HCl (1 mol HCl/36.5g HCl) = 0.274 mol HCl With 0.274mol dissolved per liter of solution the molarity is 0.274M in HCl. 28. COLLIGATIVE PROPERTIES OF SOLUTIONS 29. BOILING POINT The boiling point of a solution is always greater than the boiling point of a pure solvent. The greater the quantity of solute present in a given solvent the higher will be the boiling point of the solution. 30. FREEZING POINT The freezing point of a solution is always lower than the freezing point of pure solvent. 31. OSMOTIC PRESSURE Osmosis refers to the movement of solvent through a semi permeable membrane from a region of low concentration to a region of high concentration. 32. VAPOR PRESSURE The particles of pure water will tend to evaporate faster than the particles of water in a solution. This is because the interaction between solute and solvent is stronger than the interaction between solvent and another solvent. If evaporation is faster in pure water, its vapour pressure, its vapour pressure will be higher. Thus, the vapour pressure of a solution is always lower than the vapour pressure of pure solvent. 33. ACIDS AND BASES 34. ACIDS -compounds that tend to give up hydrogen ion (H+). -usually sour -react with bases to form salt 35. ACIDS Examples Vinegar Calamansi juice Car battery acid 36. BASES -compounds that tend to receive a hydrogen ion (H+). -usually bitter -reacts with acids to form salts 37. BASES Examples lye baking soda spirit of ammonia 38. ACIDS AND BASES Neutralization reaction between an acid and a base, forming salt and water Acids in the atmosphere are usually produced by nitrogen oxides and sulfur oxides that are released into the atmosphere from the burning of fossil fuels. They may be carried to the ground by rain. 39. Thank You!