Unit 1 Classification (Part II) PDF

RND 11903 BIOCHEMISTRY and NUTRITION CLASSIFICATION OF BIOLOGICAL STRUCTURE (PART II)  SUBTOPICS 1 Basic chemistry 2 Macromolecules 3 Solubility 4 Cell structure 5 Genetic material 2 SOLUBILITY 3  LEARNING O...

RND 11903 BIOCHEMISTRY and NUTRITION CLASSIFICATION OF BIOLOGICAL STRUCTURE (PART II)  SUBTOPICS 1 Basic chemistry 2 Macromolecules 3 Solubility 4 Cell structure 5 Genetic material 2 SOLUBILITY 3  LEARNING OUTCOMES At the end of the topic, students should be able to: define solubility, solution, solute and solvent; describe the different types of solution; explain the factors affecting solubility; read and interpret the solubility curve. 4  SOLUBILITY Solubility is defined as the amount of solute (in grams), that can be dissolved in a certain solvent at a specific temperature. E.g. the solubility of sodium chloride, table salt is 36 grams per 100 grams of water at 20 degree Celsius 5  DEFINITION OF TERMS Solution – a homogeneous mixture of two or more substances of ions or molecules Solute – the part of a solution that is being dissolved (usually the lesser amount) Solvent – the part of a solution that dissolves the solute (usually the greater amount) 6 DEFINITION OF TERMS Water is often used as a solvent 7  TYPES OF SOLUTION Saturated – a solution that contains the maximum quantity of solute that dissolves at a given temperature. Unsaturated – a solution that contains less than the maximum amount of solute that can dissolve at a particular temperature. 8  TYPES OF SOLUTION Supersaturated – a solution that contains more solute than a saturated solution. – Supersaturated solutions can be attained by heating the solution up to dissolve more solute at that higher temperature and then letting the solution cool. – Once cooled, agitation causes crystals to precipitate (separate from solution) out of the supersaturated solution. 9 TYPES OF SOLUTION 10  TYPES OF SOLUTION Unsaturated solution Saturated Solution 11 TYPES OF SOLUTION 12 TYPES OF SOLUTION 13 14  BRAIN AEROBIC 1 1. You add the first packet of sugar, and stir. What will happen? 2. You add a second packet of sugar and it takes a little more time for the sugar to dissolve. After stirring for a minute, you realize that there are still some sugar crystals at the bottom of the glass 3. After tasting your tea, you decide it is still not sweet enough and add more sugar. But, it all settles at the bottom, and regardless of how much you stir, the crystals stay at the bottom of the cup. 15  FACTORS AFFECTING SOLUBILITY Nature of the solvent and the solute – “Like dissolves like” Temperature Pressure (for gases) Factors that affect the rate of dissolves – Increasing temperature – stirring (agitation) – Crushing (smaller particle size) 16  FACTORS AFFECTING SOLUBILITY “Like dissolves Like” – The general principle of solubility, that is polar solvents dissolve polar solutes; and non-polar solvents dissolve non-polar solutes. – E.g. mineral acids, bases and salts which are polar, will be much more soluble in water, which is also polar. – Likewise, non-polar substances tend to be only slightly soluble in water, but very soluble in non- polar solvents. – E.g. non-polar solvent: ether, hexane 17  FACTORS AFFECTING SOLUBILITY Temperature and solubility – In general, solubility increases as temperature increases. The amount of solute that is dissolved in a solution is expressed as concentration. A solubility curve is a data based graph comparing the amount of solute that will dissolve in a given amount of solvent at various temperatures. 18  SOLUBILITY CURVE Solubility curves show the relationship between solubility and temperature. Y-axis: solute per 100 grams of water X-axis: temperature in degree Celsius Each compound has a different curve. 19 SOLUBILITY CURVE 20 SOLUBILITY CURVE On the line: saturated - full, cannot hold any more solute Below the line: unsaturated - can hold more solute Above the line: supersaturated - holding more solute then it should – very unstable 21  SOLUBILITY CURVE 150 Supersaturated Solubility(g/100 g H2O) Supersaturated Saturated solution solution Saturated 100 Unsaturated Unsaturated 50 solution solution 0 25 50 75 100 Temperature (oC)  SOLUBILITY CURVE Solubility vs. Temperature for Solids Solubility (grams of solute/100 g H2O) 140 KI 130 120 What trends do 110 NaNO3 gases you see on the 100 solids KNO3 graph? 90 80 HCl NH4Cl 70 How is the 60 NH3 KCl 50 solubility of 40 gases and 30 NaCl KClO3 20 solids different? 10 SO2 0 10 20 30 40 50 60 70 80 90 100 Temperature °C  BRAIN AEROBIC 2 How much H2O is required to just dissolve 100 g NaNO3 at 20C? 89 g 24  BRAIN AEROBIC 3 How much KCl will dissolve in 100g of water at 50C? 42 g 25  BRAIN AEROBIC 4 Solubility vs. Temperature for Solids Solubility (grams of solute/100 g H2O) 140 KI 130 If you stir faster, 120 NaNO3 gases will that make it 110 100 solids dissolve more? 90 KNO3 80 No, it allows the 70 HCl NH4Cl substance to dissolve 60 NH3 KCl 50 faster but NOT more. 40 Increasing the 30 NaCl KClO3 temperature does 20 helps to dissolve 10 SO2 more. 0 10 20 30 40 50 60 70 80 90 100 Temperature  BRAIN AEROBIC 5 A. Solids dissolved in liquid B. Gases dissolved in liquid Solids are more soluble at higher temperature. Gases are more soluble at lower temperature & higher pressure. RECAP … 28 29