Chemistry: Density and Material Density Essay

Submitted By cindy126c
Words: 1035
Pages: 5
Open Document
MEASUREMENT OF DENSITY

Introduction

In order to classify and identify materials of a wide variety, scientists use numbers called physical constants (e.g. density, melting point, boiling point, index of refraction) which are characteristic of the material in question. These constants do not vary with the amount or shape of the material, and are therefore useful in positively identifying unknown materials. Standard reference works have been complied containing lists of data for a wide variety of substances. The chemist makes use of this in determining the identity of an unknown substance, by measuring the appropriate physical constants in the laboratory, consulting the scientific literature, and then comparing the measured physical constants with the values for known materials. This experiment illustrates several approaches to the measurement of the density of liquids and solids.
Density is a measure of the “compactness” of matter within a substance and is defined by the equation:

Density = mass/volume eq 1.

The standard metric units in use for mass and volume respectively are grams and milliters or cubic centimeters. Thus, density has the unit grams/milliter (g/ml) or grams/cubic centimenters (g/cc). The literature values are usually given in this unit. Density may be calculated from a separate mass and volume measurement, or, in the case of liquids, may be determined directly by the use of an instrument called hydrometer.
Volume measurements for liquids or gases are made using a graduated containers, for example, a graduated cylinder. For solids, the volume can be obtained either from the measurement of the dimensions of the solid or by displacement. The first method can be applied to solids with regular geometric shapes for which the mathematical formulas can be used to calculate the volume of the solid from the dimensions of the solid. Alternatively, the volume of any solid object, irregular or regularly shaped, can be measured by displacement. The solid is submerged in a liquid in which it is not soluble, and the volume of liquid displaced measured.
The hydrometer measures density directly. An object that is less dense than a liquid will float in that liquid density to a depth such that the mass of the object submerged equals the mass of the of the liquid displaced (Archimedes' Principle). Since mass equals density X volume (see equation 1), an object floated in liquids of different densities will displace different volumes of liquid. A hydrometer is a tube of constant mass that has been calibrated to measure density by floating the hydrometer in liquids of known densities and recording on a scale the fraction of the hydrometer submerged. Any hydrometer can be used over a limited range of densities because the hydrometer must float in the liquid being studied and the hydrometer level must be sufficiently submerged to obtain an on scale reading. Hydrometers may be calibrated in g/ml or some other unit of density.
In the following experiment, the identities of three colorless liquids will be determined by measuring the densities of the liquids by two methods and then comparing the density of the liquid to literature (reference) values for the three liquids. The identity of an unknown metal will be established in a similar manner.

Procedure

1) Weigh a clean, dry 50ml graduated cylinder. Add approximately 30ml of liquid to your weighed 50ml graduated cylinder without bothering to measuring out the liquid accurately. Now carefully read and record whatever amount of liquid there is in the cylinder. Weigh the cylinder and liquid, and then calculate the density of the liquid. Repeat this procedure to find the density of each liquid

2) Determine the density of each of the above, using a hydrometer and an ungraduated cylinder. Read the density from where the liquid crosses the hydrometer's scale.

3) Weigh and record the mass of an unknown metal cylinder. Also record
Show More

Related Documents: Chemistry: Density and Material Density Essay

Labs: Metal and Nr Essay

composed of two or more elements. Alloying a metal is done by combining it with one or more other metals or non-metals that often enhance its properties. For example, steel is stronger than iron, its primary element. The physical properties, such as density, reactivity. The term alloy is used to describe a mixture of atoms in which the primary constituent is a metal. The primary metal is called the base, the matrix, or the solvent. The secondary constituents are often called solutes. If there is a mixture…

Words 723 - Pages 3

Essay on Determining Density

9/3-9/4 Determining Density Materials: PPE: goggles, aprons Dry 50 ml graduated cylinder Dry 100 ml graduated cylinder Balance RO/DI Water Squirt bottle Reference Chart of Water Density at various temperatures Thermometer (°C) 200 g reference standard Procedure: Days 1&2 1) Followed procedure as outlined in the handout with the following changes: Before doing step 1, find the mass of a 200 g reference…

Words 473 - Pages 2

English: Electron and Density Essay

The objective of this experiment is to gain an understanding of specific materials and their properties by measuring a variety of characteristics of each material, including weight, volume, conductivity, and hardness. Throughout the experiment, we learn that different types of materials will, in most cases, have different properties. Specifically, our measurements have shown that metals have a higher density, malleable and ductile, and are excellent electrical conductors. Polymers, however…

Words 1426 - Pages 6

02 Measuring Mass Length Volume And Den Essay

Measuring Mass, Length, Volume and Density Exactly how “good” is a measured number? Pre-Lab Assignments: Before doing this lab you should have completed the following prelab tutorials or taken the corresponding fast-track quizzes demonstrating your proficiency. Measurements and Units Significant Figures Student Learning Outcomes: How to properly make and record measurements taken with both analog and digital measurement devices with the maximum precision. The rules for the use and importance…

Words 3606 - Pages 15

Chemistry: Atom and Electrons Essay

Chemistry – Topic 4 Revision notes C2.17: Chemical Classification The atoms of elements in a compound are held together with chemical bonds. The type of bonding affects the properties of the material. Ionic bonds form when a metal reacts with a non-metal. Covalent bonds form between atoms of non-metal elements. Metals are good conductors of heat and electricity and are solids at room temperature. Mercury (metal) is a liquid at room temperature. Metals don’t dissolve in water, they are malleable…

Words 531 - Pages 3

Essay on Chem Chapter 1 P

Definition of Chemistry: • Chemistry is the study of the composition, structure, and properties of matter, the processes that matter undergoes, and energy changes that accompany these processes. Branches of Chemistry • • • • • • • • 1. 2. 3. 4. 5. 6. 7. 8. organic chemistry inorganic chemistry physical chemistry analytical chemistry Biochemistry Theoretical chemistry Branches of chemistry: • 1. Organic chemistry: the study of most carbon-containing compound • • 2. Inorganic chemistry: the study…

Words 1104 - Pages 5

Forensic Evidence Glass 1 Essay

criminal investigations. I will examine how investigators identify, collect (handle), evaluate, and compare and contrast glass as it pertains to a criminal investigation. First, we will examine the history of glass. Glass is a product of inorganic materials that solidified, but did not crystallize. Glass is mainly composed of silicon dioxide (SiO2), and is extremely prevalent in everyday life. Usually, windows are the most fragile elements of a building or a vehicle, and thereby are broken by thieves…

Words 1333 - Pages 6

Bio 1301 Unit 1 Lab Report

or regulations. 2. What is the difference between a'smart' and a'smart'? Protective means to provide defense or safety against harm or danger. 3. What is the difference between a'smart' and a'smart'? Transport refers to moving people, goods, or materials from one place to another. 4. What is the difference between a.. Receptors are specialized cells or structures that detect and respond to specific stimuli in the environment. Nucleic Acids Nucleotides A molecule of sugar, along with a phosphate and…

Words 616 - Pages 3

Carbonization Of Charcoal Products

CARBONIZATION OF WOOD FOR ADVANCED MATERIALS APPLICATIONS C. The Johns Hopkins University, E. BYRNE and D. C. NAGLE* Department of Materials U.S.A. Science and Engineering, Baltimore, MD 21218, (Received 19 August 1996; accepted 6 September 1996) Abstract-A unique process for conversion of monolithic wood structures to carbons that retain the cellular structure of the wood without the formation of cracks and other defects associated with charcoal materials is described. A variety…

Words 5338 - Pages 22

Essay on The Unknown Substance Lab

Unknown Substance Lab Purpose/Problem: The student will use chemical and physical properties to identify unknown substances. 1) Introduction: Physical properties were documented for each substance including visual description, solubility in water and density. A physical property is an observable property of a system and can be either intrinsic or extrinsic if the amount of the substance changes its properties. In addition to physical properties, the substances were evaluated using their chemical properties…

Words 1195 - Pages 5