Why are we measuring the density of the same liquid

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Unformatted text preview: ed cylinder from the volume of the liquid in the graduated cylinder with the object. To get density, divide the mass of the object by its volume. Dakota State University Page 50 of 232 Experiment 1: Density of a Liquid and a Solid General Chemistry I and II Lab Manual Data and Observations Part I: Pipette Graduated cylinder Flask Mass of empty beaker Mass of beaker and liquid Mass of Liquid Density of liquid Observations: Part II: Mass of object Volume with object Volume without object Volume of object Density of Object Observations: Dakota State University Page 51 of 232 Experiment 1: Density of a Liquid and a Solid General Chemistry I and II Lab Manual Pre-Lab Questions 1. Why are we measuring the density of the same liquid using three different techniques? 2. How do we determine the volume of an oddly shaped solid? 3. What volume of liquid are we using to determine the density? 4. Who developed the method of volume by water displacement? Dakota State University Page 52 of 232 Experiment 1: Density of a Liquid and a Solid General Chemistry I and II Lab Manual Post-Lab Questions 1. What is the quickest method for determining the volume of a liquid? Which is the most accurate? 2. How do your densities compare with the three methods of volume determination from part I for the liquid? 3. How would you measure the volume of a sample of sand? 4. For each of the following, what technique would you choose for measuring the volume? (a) You want to take 50 mL of a reagent from the area that it is stored to your desk (b) A titration requires 10.00 mL of a reagent measured as accurately as possible (c) A synthesis requires 35 mL of acid Dakota State University Page 53 of 232 Experiment 2: Compound Types General Chemistry I and II Lab Manual Experiment 2: Compound types Purpose: To examine the difference between ionic and covalent compounds and understand how their properties give rise to this categorization Percolate: To bubble, usually as a result of applied heat Background: See “Using the Pasco System” Introduction: It is amazing what early chemists accomplished even without an understanding of atomic make-up. I love reading old chemistry textbooks to see how they justified some of the ir conclusions, which, with a few exceptions, were right on target. I even have one book that discusses the octet rule in terms of “valencies”, and have it exactly right. What is interesting about this is that at the back of the book, they talk about this new sub-atomic particle that they are tentatively calling the “electron”. Another thing they had correct was the categorization of compounds into “covalent” and “ionic”. In class, we discuss these compounds in terms of electrons, wherein ionic compounds transfer electrons and covalent compounds share electrons. How did the early chemists classify compounds, though, when they did not know what electrons were? They used properties, such as solubilities, melting points, and conduction. Solubility helps us to classify compounds as polar or non-polar, because, as a general rule, polar solutes dissolve in polar solvents (like water), while non-polar solutes dissolve in non-polar solvents (like oils). Conductivity means whether or not a compound will cond uct electricity when it is dissolved in water. We call these “electrolytes”, which are just...
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This note was uploaded on 09/18/2012 for the course CHEMISTRY 1010 taught by Professor Kumar during the Fall '11 term at WPI.

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