Identification of a Substance by Physical Properties (UAEU Chemistry)

EXPERIMENT 1: Identification of a Substance by Physical Properties Department of Chemistry By: Abdalla Jamal Objective: ‫نقطة‬ ‫كثافة...

EXPERIMENT 1: Identification of a Substance by Physical Properties Department of Chemistry By: Abdalla Jamal Objective: ‫نقطة‬ ‫كثافة قابلية الذوبان‬ To learn the use of physical properties such as solubility, ‫الغليان‬ ‫نقطة االنصهار‬ density, boiling point, and melting point in identifying ‫تحديد‬ ‫المواد الصلبة‬ liquids and solid ‫السوائل‬ substances Introductio ‫لها مجموعة فريدة من الخصائص‬ ‫التمييز بين واحد‬ ‫المادة‬ n: Every substance has a unique set of properties that allow us to differentiate one from another Properties of matters: Physi Chemi cal cal Can be‫تغيير‬ determined or ‫تغير في التكوين‬ ‫بدون‬ Involve a change in the measured without changing ‫التركيبة‬ composition of the matter or the composition or identity of material the substance Examples: Color, order, Such properties include reaction density, B.P, M.P, solubility, with oxygen (oxidation), chlorine, etc. metals, etc. ‫مكث‬ The physical properties can ‫ ف‬be ‫واسع النطاق‬ either: Intensive or Extensive  Physical properties can be further classified into Intensive and Extensive ‫خصائص مكثفة‬ ‫ال تعتمد على كمية‬ Intensive properties: properties that ‫ المادة‬are independent of the ‫يتم فحصها ويمكن استخدامها لتحديد مادة ما‬. amount of substance being examined and can be used to ‫الذوبان‬ identify a substance. ‫نقطة الغليان نقطة االنصهار‬ ‫كثافة‬ Such as: solubility, melting point, boiling point, color and density. ‫خصائص واسعة النطاق‬ ‫تعتمد على كمية المادة الموجودة و‬ Extensive properties: Properties that depend on the amount of ‫ليس مفيًدا في تحديد المادة‬ substance present and are not useful in the identification of a substance. uch as: mass and volume In this lab, we use two physical properties to identify a liquid substance: Solubility and density  What is ‫قابلية‬ Solubility? ‫كمية‬ ‫يذوب في مذيب‬ Solubility is a measure of the amount of substance that can dissolve ‫الذوبان‬ ‫المادة‬ ‫معين‬ in a given solvent at a given condition ‫قابلية المادة‬ )‫كتلة المادة (المذاب‬ Solubility ‫للذوبان‬ of a substance is usually defined ‫بالجرام‬as the mass in ‘g’ of the substance (solute) which will dissolve in a 100g of a given solvent at a given‫درجة‬ ‫ جرام من مذيب معين عند‬100 ‫يذوب في‬ temperature ‫حرارة معينة‬ Important ow to predict solubility? ‫تذوب المركبات القطبية‬ ‫المذيب القطبي‬ ‫القاعدة‬ ‫المذاب في مثل‬ Like dissolved in ‫!مثل‬ olar compounds dissolve in polar solvent like rule! ‫المركبات غير‬ ‫تذوب‬ ‫مذيب غير قطبي‬ Nonpolar compounds dissolve in ‫القطبية‬ nonpolar solvent ‫التعبير عن الذوبان‬ w do we express solubility? ‫قابل للذوبان‬ ‫مركب مذاب في مذيب‬ Soluble (S) If the compound dissolved in a ‫قابلة لالمتزاج‬ solvent “miscible” ‫قابل للذوبان‬ ‫جزئيا‬ ‫مركب غير قابل للذوبان في‬ Partially If the compound insoluble in a ‫ غير قابل‬soluble ‫المذيب‬ (PS) solvent “immiscible” ‫للذوبان‬ ‫غير قابل لالمتزاج‬  Density: ‫يتم قياسه عادة بالجرام والحجم بالملليلتر أو يتم تعريفه على أنه كتلة لكل وحدة حجم‬ Density is defined as mass per unit volume. 3‫السم‬. Mass is usually measured in g and volume in mL or cm3. Common chlorinated Density (g/mL) solvents Density = mass / volume CH2Cl2 1.33 g/mL Important CHCl3 1.489 g/mL D=m/V CCl4 1.587 g/mL ‫الخاصية المميزة‬ Density is a characteristic property of a substance, therefore, it is ‫للمادة‬ ‫مركب غير معروف‬ ‫لتحديد‬ a useful physical property to identify an unknown compound. Density of water (25°C) = 0.9970 g/cm3 The density of liquid: Because 1 mL‫مقابل‬ is equivalent g/mL to 1 cm3, these‫للتبديل‬ units‫قابلة‬ are The density of solid: interchangeable. g/cm3  Experiment Part A: Solubility Apparatus: Test tubes, Test tube rack, Dropper, 10 mL graduate cylinder Chemicals: Sodium chloride, Cyclohexane, Naphthalene, water  Experiment Part A: Solubility Procedure: 1. Take two test tubes and set them in a rack. 2. Add 2 mL of water to the fist test tube and 2 mL of cyclohexane to the second test tube 3 Add few crystals of your first unknown solid to each of the test tubes and shake for a while. 4. Record your observation in the data sheet ‘s’ for soluble, or ‘I’ for insoluble. 5. Dispose the liquids in the waste container, and do the same experiment for your second unknown solid. 6. Record your observation in the data sheet ‘s’ for soluble, or ‘I’ for insoluble. 7. Identify the unknown sample using your observation (refer the table) Part B: Density Apparatus: 10 mL graduate cylinder Chemicals: Nickel ball Procedure: 1. Take the weight of the given Nickel ball 2. Measure 5 mL of water in a 10 mL graduate cylinder and record the volume 3. Carefully drop the Nickel ball in the graduated cylinder and record the new volume 4. Calculate the density of the nickel and record 5. Repeat the experiments two more times and find average density.  Report Sheet Name: ___________________________ Instructor: ___________________________ Date: ___________________________ LIQUID PART A. Solubility Liquid: Unknown Number __________ Solubility: Water __________ Ethanol __________ SOLID PART A. Solubility Solid: Unknown Number __________ Solubility: Water __________ Ethanol __________ PART B. Density Mass of the solid __________ g Initial Volume of the Liquid __________ ml Final Volume of the Liquid __________ml Volume of the Solid Unknown __________ ml Density of the Solid Unknown __________ g/ml