Lecture 1: States of Matter (Part 1) - Physical Pharmacy I

Lecture 1: States of matter (part 1) Physical Pharmacy I Ghalib Albaaj PhD in pharmaceutics Al-Esraa University College Introduction The most common three states of matter are gas, liquid, and solid, but there is a fourth state of matter which is plasma. Solid Liquid...

Lecture 1: States of matter (part 1) Physical Pharmacy I Ghalib Albaaj PhD in pharmaceutics Al-Esraa University College Introduction The most common three states of matter are gas, liquid, and solid, but there is a fourth state of matter which is plasma. Solid Liquid Gas Plasma Fixed shape No fixed shape No fixed shape No fixed shape Definite volume Definite volume No definite No definite volume volume Strong attraction Lower attraction Small attraction Small attraction forces forces forces forces Vibrate in its Fast motion but Move freely loosely packed position only stay close to each other Neutral molecules or atoms Positive nuclei and negative electrons  Repulsive and Attractive Forces  when two atoms become close to each other, the opposite charges and binding forces Attraction ‫شحونة سلبًا‬+‫لكترونات الخارجية ا‬7‫ تت;مس سحب ا‬،‫عندما تصبح الجزيئات قريبة ج ًدا‬ When the molecules become too close, the outer negatively charged electron clouds touch Repulsion  Attractive forces are subdivided into:  Cohesive forces: are the attraction of like molecules.  Adhesive forces: are the attraction of different molecules to each other. Binding forces Types of bonding Intermolecular forces Intramolecular forces (present between molecules) (present within a molecule) Weak forces Strong forces Ionic Covalent Metallic Bond energy bonds bonds bonds (100 -1000) kcal/mole Bond energy (50-100) kcal/mole.  Intramolecular bond: Covalent bond Nonpolar molecule ‫ن ا)لكترونات‬, ‫ توجد شحنة على الذرات‬: ;‫الرابطة تتقاسم بالتساوي ب; الذرت‬ No charge on the atoms because bonding electrons shared equally between the two atoms Intramolecular bond: Covalent bond ‫شحنات جزئية على الذرات بسبب تقاسم‬ Polar molecule ;‫ا)لكترونات الرابطة بشكل غير متسا ٍو ب; الذرت‬ Partial charges on the atoms because bonding electrons shared unequally between the two atoms Intramolecular bond: Ionic bond Full charges on the atoms because of the complete transfer of one or more valence electrons. ‫الشحنات الكاملة على الذرات بسبب النقل الكامل )لكترون واحد‬.‫أو أكثر من إلكترون التكافؤ‬ ‫ﻟﻠﻔﮭﻢ و‬ ‫اﻻطﻼع ﻓﻘﻂ‬ Intermolecular forces For molecules to exist as aggregates in gases, liquids, and solids, intermolecular forces must exist. Intermolecular forces Van Der Hydrogen Ion-Induced Ion–Dipole Waals forces bonds Dipole Forces Forces Van der Waals forces Dipole-dipole (Keesom forces) Dipole-induced dipole (Debye forces) Induced dipole-induced dipole (London forces) a) Dipole-dipole forces (Keesom forces):  They occur when polar molecules possessing permanent dipoles, having both a partial positively charged end and a partial negatively charged end, interact. The bond energy of Keesom forces ranges from (1-7) kcal/mole.  ‫ؤقت في الجزيئات غير‬1‫يمكن أن تنتج ثنائي القطب الكهربائي ا‬ b) Dipole-induced dipole forces (Debye forces):  A polar molecule can produce a temporary electric dipole in nonpolar molecules. c) Induced dipole-induced dipole or dispersion forces (London forces):  Nonpolar molecules can induce polarity in one another. This attraction is produced by asymmetry in the distribution of the electrons around the nucleus, dispersion effect. These forces are also temporary. Their bond energy is about (0.5 -1) kcal/ mole.  Ion-dipole and ion-induced dipole forces  These attraction forces take place between nonpolar or polar molecules and ions.  The bond energy is about (1-7) kcal/mole Hydrogen bonding ‫تحدث نتيجة للتفاعل ب' جزيء يحتوي على ذرة هيدروج' وذرة ذات‬.'‫كسج' أو النيتروج‬E‫كهرسلبية قوية مثل الفلور أو ا‬  Occur as a result of interaction between a molecule containing a hydrogen atom and a strongly electronegative atom such as fluorine, oxygen, or nitrogen.  Hydrogen bonds are considered a special type of dipole-dipole forces.  Many of water unusual properties are attributed to hydrogen bonds such as its:  High dielectric constant ‫ترجع العديد من الخصائص غير العادية للماء‬  High boiling point :‫إلى الروابط الهيدروجينية مثل‬ ‫رتفع‬C‫ثابت العزل الكهربائي ا‬  Low vapor pressure. ‫رتفعة‬C‫نقطة الغليان ا‬.‫نخفض‬C‫ضغط البخار ا‬  Hydrophobic interactions.(‫اء‬#‫ائي )ا‬#‫ الجزيئات غير القطبية والوسط ا‬8‫تحدث ب‬.‫ وهذا ما يُعرف بالتأثير الكاره للماء‬،‫اء توجيه نفسها لتشكل بنية تشبه القفص حول الجزيئات غير القطبية‬#‫تعيد جزيئات ا‬  Occur between nonpolar molecules and aqueous medium (water).  Water molecules reorient forming a cage-like structure around the nonpolar molecules, this is known as the hydrophobic effect. The Gaseous State ‫ وترتبط‬،‫ تمتلك جزيئات الغاز طاقة حركية أعلى وحركة سريعة‬-.‫ الجزيئات ضعيفة للغاية‬C‫ببعضها البعض بواسطة قوى ب‬ Gas molecules have higher kinetic energy and rapid motion, they are held together by very weak intermolecular forces. of gas is expressed in:  dyne/cm2 (force/unit area) 1 atm =760 mmHg  atmospheres 0º Celsius =273 K  millimeters of mercury measured by Liter or (1 ml=1cm3) is measured in Kelvin (absolute) The Ideal Gas Law Ideal gas molecules are assumed:  to have no intermolecular interactions  to be perfectly elastic during collisions with no energy exchange. Ideal gas law is derived from Boyle, Charles and Gay-Lussac laws. Boyle’s law ،‫ينص قانون بويل على أنه "بالنسبة لكتلة معينة من الغاز عند درجة حرارة ثابتة‬.‫ وهما متناسبان عكسيًا‬."(k) ‫( ثابتًا‬p) ‫( والضغط‬V) ‫يكون حاصل ضرب الحجم‬ Boyle’s law states “for a given mass of gas at fixed temperature, the product of volume (V) and pressure (p) are constant (k)”. They are inversely proportional. or Charles law ،‫ينص قانون شارل على أنه "بالنسبة لكتلة معينة من الغاز عند ضغط ثابت‬."‫طلقة يتناسبان بشكل طردي‬N‫فإن الحجم ودرجة الحرارة ا‬ Charles law states “for a given mass of gas at fixed pressure, the volume and absolute temperature are directly proportional”. Or T : temperature in Kelvin  ‫ينص قانون جاي لوساك على أن "الضغط ودرجة الحرارة ا(طلقة لكتلة‬ The Gay- Lussac law "‫معينة من الغاز عند حجم ثابت يتناسبان بشكل طردي‬ The law of Gay-Lussac states “the pressure and absolute temperature of a given mass of gas at fixed volume are directly proportional” Or  Boyle, Gay-Lussac and Charles law can be combined to obtain the relationship: Or Used for two sets of conditions Example A sample of methane CH4 has a volume of 7.0 dm3 at a temperature of 4°C and a pressure of 0.848 atm. Calculate the volume of methane at a temperature of 11°C and a pressure of 1.52 atm? Home Work A gas occupies a volume of 30.0 mL at a temperature of 20°C and a pressure of 740 mm Hg. Assuming the gas is ideal, what is the volume at 0°C and 760 mmHg? Molar gas constant ( R) The constant is the value R, the ideal gas constant. The R value = 0.08205 L atm/K mole When:  P = 1 atm  V = 22.4 L (volume of 1 mole of an ideal gas)  T = 273°K  R can also be expressed by energy units: 1 cal = 4.184 joules. 𝟏 𝟖.𝟑𝟏𝟒 𝒋𝒐𝒖𝒍𝒆𝒔.𝒎𝒐𝒍 𝟏 𝑲 R= = 1.987 cal/mol. K 𝟒.𝟏𝟖𝟒 𝒋𝒐𝒖𝒍𝒆𝒔.𝒄𝒂𝒍 𝟏 General ideal gas law It is also called the equation of state of an ideal gas: This equation is correct for 1 mole of gas. For n moles, the equation becomes: Example What is the volume of 2 moles of an ideal gas at 25°C and 780 mmHg? Real Gases  Real gases, unlike ideal gases, are composed of molecules with finite volume and have a tendency to attract each other.  Thus the terms of pressure and volume in ideal gas equation are modified to meet the experimental results in real gases.