BIOO211 Session 3 Introduction To Reaction Rates and States of Matter Department of Biosciences www.endeavour.edu.au
Chemistry & Biochemistry Reaction Rates and States of Matter, Gases and Solutions This session includes: 1. Reactions and rates 2. States of matter 3. Gases 4. Introduction to solutions Solutions, colloids and suspensions defined Solution, solvent, solute Hydration - how a substance dissolves Soluble vs insoluble Effect of temperature Concentration and its units Chemical calculations Endeavour College of Natural Health www.endeavour.edu.au 2
Collision Theory of Reactions A chemical reaction occurs when o Collisions between molecules have sufficient energy to break the bonds in the reactants. o Molecules collide with the proper orientation. o Bonds between atoms of the reactants (N 2 and O 2 ) are broken, and new bonds (NO) form. Copyright 2013 by Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 3
The activation energy Activation Energy o Is the minimum energy needed for a reaction to take place upon proper collision of reactants. 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 4
Rate of reaction for ionic and covalent compounds o Ionic reactions occur rapidly. Activation energies for such reactions tend to be low as no breaking of covalent bonds is required. o Reactions which require the breaking of covalent bonds are slow and have higher activation energies Endeavour College of Natural Health www.endeavour.edu.au 5
Factors affecting reaction rate o Reaction rate is the speed at which reactant is used up or the speed at which product is formed. o Temperature Reaction rate Increases when temperature rises because reacting molecules move faster, providing more colliding molecules with energy of activation o Concentration Increasing the concentration of reactants, increases the number of collisions and Increases the reaction rate. 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 6
Activation Energy and Enzymes Enzymes are catalysts in biological systems Catalysts and enzymes speed up reactions by lowering the activation energy However, in a reversible reaction, they speed up the forward and reverse reactions equally, and therefore so not alter the position of equilibrium (Timberlake, 2016) Endeavour College of Natural Health www.endeavour.edu.au 7
Factors that increase reaction rate o More reactants, increases reaction rate and favours forward direction in the equilibrium o Catalyst increases reaction rate but speeds up both forward and reverse reactions of a reversible equilibrium Endeavour College of Natural Health www.endeavour.edu.au 8
Energy and states of matter - Potential Energy Potential energy is energy stored for use at a later time. Examples are o Water behind a dam. o A compressed spring. o Chemical bonds in petrol, coal, or food. Endeavour College of Natural Health www.endeavour.edu.au 9
Energy and states of matter - Kinetic Energy Kinetic energy is the energy of matter in motion. Examples are o Swimming. o Water flowing over a dam. o Working out. o Burning petrol in car engine. Endeavour College of Natural Health www.endeavour.edu.au 10
States of matter o Three states of matter: solid, liquid, gas o Each state has particular characteristics, o Changes of state are: melting (s l) and freezing (l s); boiling (l g) and condensation (g l), sublimation (s g) and deposition (g s). These are physical changes o Inter molecular forces are overcome o Melting points indicate attractive forces o http://www.harcourtschool.com/activity/states_of_matte r/ Endeavour College of Natural Health www.endeavour.edu.au 11
Comparison of solid, liquid and gas Solid Liquid Gas Definite shape and volume indefinite shape, but a definite volume indefinite shape and indefinite volume Particles are close together in a fixed arrangement and move very slowly, very strong interaction Particles have least amount of kinetic energy and greatest amount of potential energy particles are close together move slowly. Particles have strong interaction Increased amounts of kinetic energy and have a moderate amount of potential energy Particles are far apart and move fast, no interaction between particles Particles have the greatest degree of kinetic energy and the least potential energy E.g. Ice, iron E.g. Water, vinegar E.g. Air, water vapour Endeavour College of Natural Health www.endeavour.edu.au 12
Changes in state melting (s l) freezing (l s) boiling (l g) condensation (g l), sublimation (s g) and deposition (g s). Endeavour College of Natural Health www.endeavour.edu.au 13
Attractive Forces Between Particles Forces that hold particles together in liquids, solids and gases (at low temperatures) include: o Ionic compounds ionic bonds o Covalent compounds Hydrogen bonds Dipole-dipole attractions Dispersion forces Endeavour College of Natural Health www.endeavour.edu.au 14
Attractive forces and bonding Ionic bond Dipoledipole attraction Dispersion force In ionic compounds, ionic bonds are strong attractive forces. Attractive forces between positively and negatively charged ends of polar covalent molecules; called hydrogen bonds when hydrogen atoms in one molecule are attracted to the strongly electronegative atoms Cl, F, O, or N in another molecule Weak attractions between nonpolar molecules. Caused by temporary dipoles that develop when electrons are not distributed equally. Refer to Table 6.17 (Timberlake, 2016, p. 251) for a summary, showing dispersion forces to be the weakest intermolecular force Endeavour College of Natural Health www.endeavour.edu.au 15
Ionic bonds>hydrogen bonds>dipole-dipole interactions>dispersion forces o Ionic bond e.g. between Na+ and Cl very strong inter-particle force; high MP for a pure ionic solid o Hydrogen bond, moderately strong inter-molecular force; pure substances melt closer to room temp. (Timberlake, 2013, p. 195) Endeavour College of Natural Health www.endeavour.edu.au 16
Concept Map Matter and Energy Endeavour College of Natural Health www.endeavour.edu.au 17
Summary, reaction rates and changes of state Summary Session 3 (Part 1) 1. Define reaction rate and equilibrium. 2. Discuss the factors that affect rate of reaction. 3. Define potential and kinetic energy 4. Define intermolecular forces and describe the different types of Intermolecular forces 5. Define the relationship between kinetic energy and states of matter. 6. Describe the three main types of mixtures: solutions, colloids and suspensions. 7. Define the terms freezing, melting, boiling and condensation and outline the factors that affect the melting and boiling points of substances. Endeavour College of Natural Health www.endeavour.edu.au 18
What s a gas? Kinetic Theory of Gases A gas consists of small particles that o Move rapidly in straight lines. o Have essentially no attractive (or repulsive) forces. o Are very far apart. o Have very small volumes compared to the volume of the container they occupy. o Have kinetic energies that increase with an increase in temperature. 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 19
Properties of Gases o Gases are described in terms of four properties: pressure (P), volume (V), temperature (T), and amount (n). Endeavour College of Natural Health www.endeavour.edu.au 20
Gas Pressure Gas pressure o Is the force acting on a specific area. Pressure (P) = force area o Has units of atm, mm Hg, torr, lb/in. 2 or p/si and kilopascals (kpa). 1 atm = 760 mm Hg (exact) 1 atm = 760 torr 1 atm = 14.7 lb/in. 2 or p/si 1 atm = 101.325 kpa Endeavour College of Natural Health www.endeavour.edu.au 21
Boyle s Law Boyle s Law states that o The pressure of a gas is inversely related to its volume when T and n are constant. o If the pressure increases, volume decreases. P 1 = 1 atm V 1 = 4 L P 1 V 1 = constant (when T and n constant) P 1 V 1 = P 2 V 2 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 22
Boyles Law and Breathing During inhalation, o Chest cavity volume increases, P in lungs decreases During exhalation, o Chest cavity volume decreases, P in lungs increases 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 23
Calculation with Boyle s Law Freon-12, CCl 2 F 2, is used in refrigeration systems. What is the new volume (L) of a 8.0 L sample of Freon gas initially at 550 mm Hg after its pressure is changed to 2200 mm Hg at constant T? STEP 1 Set up a data table Conditions 1 Conditions 2 P 1 = 550 mm Hg P 2 = 2200 mm Hg V 1 = 8.0 L V 2 =? Endeavour College of Natural Health www.endeavour.edu.au 24
Calculation with Boyle s Law (Continued) STEP 2 Solve Boyle s Law for V 2. When pressure increases, volume decreases. P 1 V 1 = P 2 V 2 V 2 = V 1 x P 1 P 2 V 2 = 8.0 L x 550 mm Hg = 2.0 L 2200 mm Hg Endeavour College of Natural Health www.endeavour.edu.au 25
Learning Check Boyle s Law A sample of helium gas in a balloon has a volume of 10. L at a pressure of 0.90 atm. At 1.40 atm (T constant), is the new volume represented by A, B, or C? 2016 by Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 26
Solution Boyle s Law A sample of helium gas in a balloon has a volume of 10. L at a pressure of 0.90 atm. At a higher pressure (T constant), the new volume is represented by the smaller balloon A. 2007 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 27
Partial pressure (Dalton s Law) o The total pressure of a gas mixture depends on the total number of gas particles, not on the types of particles. o In a mixture of gases, the partial pressure of each gas is the pressure that gas would exert if it were by itself in the container o The total pressure exerted by a gas mixture is the sum of the partial pressures of the gases in that mixture. P T = P 1 + P 2 +... 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 28
Blood Gases o In the lungs, O 2 enters the blood, while CO 2 from the blood is released. o In the tissues, O 2 enters the cells, which release CO 2 into the blood. 2016 by Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 29
Concept Map - Gases 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 30
Introduction to Solutions: Solutions, Solutions o Are homogeneous mixtures of two or more substances. o Consist of a solvent and one or more solutes. Solute and Solvent defined 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 31
(Timberlake, 2016 p.358) Examples of Solutions The solute and solvent in a solution can be solid, liquid, and/or gas. 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 32
Like dissolves like o Water dissolves ionic compounds and covalent molecules with dipole-dipole interactions or hydrogen bonding o Non-polar covalent molecules dissolve in nonpolar molecules Endeavour College of Natural Health www.endeavour.edu.au 33
Water o is the most common solvent; o is a polar molecule; o forms hydrogen bonds between the hydrogen atom in one molecule and the oxygen atom in a different water molecule. Water 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 34
Hydration: how a substance Na + and Cl - ions o On the surface of a NaCl crystal are attracted to polar water molecules. o Are hydrated in solution with many H 2 O molecules surrounding each ion. dissolves in water 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 35
Solubility is o The maximum amount of solute that dissolves in a specific amount of solvent. o Expressed as grams of solute in 100 grams of solvent, usually water. g of solute 100 g water Solubility o A soluble salt is an ionic compound that dissolves in water. o An insoluble salt is an ionic compound that does not dissolve in water ( BaSO 4 insoluble in water, Refer to Timberlake, 2016, p., 369) Endeavour College of Natural Health www.endeavour.edu.au 36
Unsaturated and saturated Unsaturated solutions o Contain less than the maximum amount of solute. o Can dissolve more solute. Solutions Saturated solutions o Contain the maximum amount of solute that can dissolve. o Have undissolved solute at the bottom of the container. o Supersaturated soln contains > max. amount of solute that can be dissolved in the solvent (at given T) 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 37
Solubility o Depends on temperature. Effect of Temperature o Solubility of most solids increases as temperature increases Fig 9.5(Timberlake, 2016, p. 367) on Solubility o Solubility of gases decreases as temperature increases (Timberlake, 2016, p. 368) 2016 by Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 38
Solubility and Pressure Henry s Law states o The solubility of a gas in a liquid is directly related to the pressure of that gas above the liquid. o At higher pressures, more gas molecules dissolve in the liquid (Timberlake, 2013, p. 309) 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 39
Types of mixture Solution Colloid Suspension Type of particle Contain small particles (ions or molecules). Have medium size particles Have very large particles Settling Do not settle Do not settle Settle rapidly Separation Cannot be filtered. Can be separated by semipermeable membranes. Can be filtered. Must be stirred to stay suspended Example Glucose solution Plasma Blood, calamine lotion See Table 9.12 (Timberlake, 2016, p. 385) Endeavour College of Natural Health www.endeavour.edu.au 40
Concentration and its units o The SI unit for concentration is molarity o Moles per litre = Molarity (M) measures total number of molecules in a given volume of solution a mole is Avogadro s number or the atomic mass in grams of all of its atoms For example 5 mol/l means 5 moles per litre o Concentration of a solution can also be expressed as a percentage - Percentage relative mass of a solute in a given volume of solution (eg 10% w/v) Endeavour College of Natural Health www.endeavour.edu.au 41
Units of concentration o By mass: percent %(w/w) - Number of grams of solute per 100 g of solution (or mixture) mg/g - Number of milligrams of solute per gram of solution µg/g - Number of micrograms (one millionth of a gram) per gram of solution o By volume: percent %(w/v) - Number of grams of solute per 100 ml of solution o mg/l- Number of milligrams of solute per litre of solution Other units in use: ppm parts per million (1 ppm = 1 µg/ml; also 1 mg/l) ppb parts per billion (1 ppb = 1 µg/l), where one billion equals one thousand million Endeavour College of Natural Health www.endeavour.edu.au 42
Post-Session 3 summary / revision questions: 1. Define reaction rate and equilibrium. 2. Discuss the factors that affect rate of reaction. 3. Define potential and kinetic energy 4. Define intermolecular forces and describe the different types of Intermolecular forces 5. Define the relationship between kinetic energy and states of matter. 6. Describe the three main types of mixtures: solutions, colloids and suspensions. 7. Define the terms freezing, melting, boiling and condensation and outline the factors that affect the melting and boiling points of substances. 8. Define Kinetic Molecular Theory of gases in brief. 9. Describe Boyle s Law and application to breathing (inhalation & exhalation). 10. Describe Dalton s Law of Partial Pressures and gas transport in blood. 11. Describe Henry's Law and why solubility of gases in liquids is important in biological systems. 12. Explain how the human body takes up oxygen from the air. 13. Discuss the amazing properties of water. 14. Explain the concept of solubility and the characteristics of solutions. 15. Describe how solids and gases differ in their solubility with increasing temperature. 16. Define the SI unit of concentration, Molarity. Endeavour College of Natural Health www.endeavour.edu.au 43
Concept Map - Solutions 2016 Pearson Education, Inc. Endeavour College of Natural Health www.endeavour.edu.au 44
References & Diagrams Timberlake, KC 2016, General, organic, and biological chemistry, structures of life, 5 th edn, Pearson,Boston Timberlake, KC 2013, General, organic, and biological chemistry, structures of life, 4 th edn, Pearson Benjamin Cummings, Boston Timberlake, KC 2010, General, organic and biological chemistry, 3rd edn, Pearson Benjamin Cummings Timberlake, KC 2007, General, organic and biological chemistry, 2nd edn, Pearson Benjamin Cummings Endeavour College of Natural Health www.endeavour.edu.au 45
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