Determination of substance through density

Fantastic for expaining buoyancy and density.

Determination of substance through density

Michael Evans — Georgia Institute of Technology The ratio of the mass of a substance to its volume is known as the mass density or, simply, the density of the substance. To measure the density of a sample of material, both the mass and volume of the sample must be determined.

For both solids and liquids, a balance can be used to measure mass; however, methods for determining volume are different for solids and liquids. As liquids can flow and take the shapes of their containers, glassware such as a graduated cylinder or volumetric flask can be used to measure the volume of a liquid.

The volume of an irregularly-shaped solid can be measured by submersion in a liquid — the difference in volume caused by addition of the solid is equal to the volume of the solid.

This demonstration illustrates the methods for measuring the density of solids and liquids. Using a volumetric flask and an analytical balance, the density of ethanol can be determined.

Using a graduated cylinder, analytical balance, and water as the displaced liquid, the density of zinc metal can be determined. Determining the Density of a Solid and Liquid.

Principles By definition, all matter has mass and occupies volume.

Determination of substance through density

The density of a substance is the ratio of its mass to its volume. At constant temperature and pressure, the density of a substance is constant. Thus, density can be used to identify an unknown pure substance if a list of reference densities is available, and the experimenter can choose a convenient amount of substance to work with when measuring density.

To measure the density of a sample of a substance, it is necessary to measure its mass and volume. Mass is typically measured using an analytical balance, a precise instrument that relies on the force exerted by the sample due to gravity. The container to hold the sample also used to measure volume is weighed and tared, so only the sample mass appears on the balance display when the sample is added to the container.

For liquids, this container is typically a volumetric flask, which has one marking that corresponds to a specific volume. The container is filled to the line with the liquid sample and weighed again after the empty flask has been tared.

The measured density is the ratio of the measured mass to the volume indicated on the flask. Most solid substances are irregularly shaped, which complicates volume determination.

It is inaccurate, for example, to determine the volume of a powder by measuring its dimensions. Instead of directly measuring dimensions or using glassware like a volumetric flask, it is necessary to make use of a liquid displacement method to measure the volume of an irregularly shaped solid.

A graduated cylinder containing a known volume of liquid in which the solid is insoluble is tared. The solid is added to the cylinder, and the total mass is weighed again to determine the mass of the solid.

Addition of the solid causes an upward displacement of the liquid, resulting in a new volume reading.Relative density of a substance is the ratio of mass of any volume of substance to the mass of an equal volume of water. Example 1 A globe of steel has a mass of 12g and a volume of cm³,find its relative density.

Graph 1: Determination of Density of Substance A.

Identification of Substances by Physical Properties

Weighing by difference. Through out this course you will need to do a lot of weighing. To weigh things accurately, we use the difference method.

To weigh the water in this lab take the Measuring Density Author: davis Created Date. the density determination are the areometric, bottle, hydrostatic balance, and magnetic float.

A disad- When a solution of substance A is diluted by water (a study of binary systems) or by a solution free mA through Eqs.

(6) and (1), we obtain expression (8). The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume.

The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used. Archimedes' Principle is that an object totally or partially immersed in a fluid (liquid or gas) is buoyed (lifted) up by a force equal to the weight of the fluid that is displaced.

It has numerous applications, one of which is the determination of density and specific gravity. Density Measurement 3 Another way of determining if a theory is supported by experimental data is through the use of a typical graph, data from experiments is plotted as individual.

Specific gravity - Wikipedia