# Explain density and relative density and write their formulae

Density is the measure of mass per volume. This means that density of any solid,liquid, or gas can be found by dividing its mass in kilogram by its volume in cubic metres. Lets assume our reference material is water then density relative to water will be. A small bottle weighs 20 g when empty and 22 g when filled with water. When it is filled with oil it weighs What is the density of oil?

You found the relative densities of some solids and some liquids by some activities. List the solids and liquids in increasing order of relative density. A solid sphere has a radius of 2 cm and a mass of 0. What is the relative density of the sphere? Floating bodies. Rate this question : How useful is this solution? And some sink? NEXT What is the value of density of water?

Daily Report Card. Detailed Performance Evaluation. Explain density and relative density and write formulae. How can you find the relative density of a liquid? What is the value of density of water? Which is denser, water or milk? Download our App :. Contact Us :.If you've ever been fooled by the old question, ' Which weighs more: a pound of feathers or a pound of lead?

Although the feathers and the lead both weigh exactly the same um, a poundtheir density is wildly different, and we can sometimes mentally conflate weight and density - even though they're different concepts. So - hey - don't feel dense. Read on to find out exactly what density is, how it works, and how to calculate density. Density is the mass per volume - not just the straight-up mass. So if the question was, 'Which weighs more: a ml jug full of feathers or a ml jug full of lead?

For an equal amount of space it takes up volumelead weighs much more than the feathers mass. Density can also be thought of as how compacted or compressed a substance is. A pound of feathers is filled with airy space, so it's not very dense at all, while a pound of lead feels much more solid, so it's more dense. This is why you should never comment on your Auntie Mabel's sponge cake by describing it as dense: she was probably going for something a little more airy.

Density is also what makes things float or sink. When you mix two or more substances, the most dense substance sinks to the bottom, whilst the least dense substance is more buoyant and floats to the top. Try mixing oil and water and see how they separate into layers, with the less dense oil on top.

Density is often written in mathematics as the symbol p or D. Mass can be written as m, and volume can be written as V. So if you want to be fancy, the formula looks like this:. Volume is to do with filling space: check out our guide to volume and weight and our volume calculator if you're not yet confident with it. So, if you have a kilogram of cheese with the volume of 0. Try our density calculator to make it all a piece of cake. Hopefully even better than Auntie Mabel's lemon sponge Basically, you can rearrange the structure to work out different elements.

For assistance with converting between units of mass and volume, give our weight and volume converter a try.

### Notation and Units

Why not fill up your bath and try out some different materials to see what floats or sinks? Just no electricals, please. So how come people float so easily in the Dead Sea?Density is the measurement of the amount of mass per unit of volume. In order to calculate densityyou need to know the mass and volume of the item.

## Relative Density

The formula for density is:. The mass is usually the easy part while finding volume can be tricky. Simple shaped objects are usually given in homework problems such as using a cube, brick or sphere. For a simple shape, use a formula to find volume. For irregular shapes, the easiest solution is to measure volume displaced by placing the object in a liquid. This example problem shows the steps needed to calculate the density of an object and a liquid when given the mass and volume.

Question 1: What is the density of a cube of sugar weighing Step 1: Find the mass and volume of the sugar cube.

### How to Calculate Density - Worked Example Problem

Step 2: Plug your variables into the density formula. Answer 1: The sugar cube has a density of 1. Question 2: A solution of water and salt contains 25 grams of salt in mL of water. What is the density of the salt water? This time, there are two masses. The mass of the salt and the mass of the water are both needed to find the mass of the salt water.

The mass of the salt is given, but the only the volume of water is given. We've also been given the density of waterso we can calculate the mass of the water. Now we have enough to find the mass of the salt water. Volume of the salt water is mL. Step 2: Plug your values into the density formula. Answer 2: The salt water has a density of 1. If you're given a regular solid object, you can measure its dimensions and calculate its volume. Unfortunately, the volume of few objects in the real world can be measured this easily!Densitymass of a unit volume of a material substance.

Density is commonly expressed in units of grams per cubic centimetre. For example, the density of air is 1. The densities of common solidsliquidsand gases are listed in textbooks and handbooks. The weight of a body, which is usually of more practical interest than its mass, can be obtained by multiplying the mass by the acceleration of gravity.

Tables that list the weight per unit volume of substances are also available; this quantity has various titles, such as weight density, specific weight, or unit weight. See also specific gravity.

The expression particle density refers to the number of particles per unit volume, not to the density of a single particle, and it is usually expressed as n. Article Media. Info Print Cite. Submit Feedback. Thank you for your feedback. The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree See Article History.

Read More on This Topic. In the random atomic order of a glassy solid, the atoms are packed less densely than in a corresponding crystal, leaving larger interstitial Learn More in these related Britannica articles:.

In the random atomic order of a glassy solid, the atoms are packed less densely than in a corresponding crystal, leaving larger interstitial spaces, or holes between atoms. These interstitial spaces collectively make up what is known as free volume, and they are responsible…. Density is the weight or mass of a unit volume of wood, and specific gravity the ratio of the density of wood to that of water. In the metric system of measurement, density and specific gravity are numerically identical; for example,….

This property is defined as the ratio of mass to volume of a substance. Generally the mass is measured in grams and the volume in millilitres or cubic centimetres.

Density measurements of liquids are straightforward and sometimes can aid in identifying pure substances…. History at your fingertips. Sign up here to see what happened On This Dayevery day in your inbox!

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The experiment about relative density is composed of three different activities. The first activity is about the Displacement Method for alloy, the second activity is about getting the density of a bone and the third activity is about Regular versus Diet Soft Drinks.

Relative density is the ratio of the density mass per unit volume of a substance to the density of a given reference material. Don't use plagiarized sources. In the experiment we used different formulas. The Aluminum bar was weighed and its mass was recorded. Some water was placed into a graduated cylinder and the initial water level was recorded. The Aluminum bar was placed inside the cylinder and the new water level was recorded. The volume of the Aluminum bar was computed by subtracting the initial water level from the resulting water level.

The density of the Aluminum bar was computed by dividing its mass by its volume. The calculated density was compared to the standard density 2. The density of the bone was then computed by multiplying the Relative density of the bone to the density of the water.

The weight of an empty pycnometer, the pycnometer filled with water, pycnometer filled with regular coke, pycnometer filled with coke light, and pycnometer filled with coke zero. The relative density of regular coke, coke light, ad coke zero was computed by using the formulas given.

Table 1 show the results from activity 1, table 2 for activity 2 in activity the finding is that the bone has osteopenia it is or low bone mass because the density of the bone is within 1. Relative Density. Accessed October 12, This is just a sample. You can get your custom paper from our expert writers. Check Writers' Offers. What's Your Topic? Hire a Professional Writer Now. The input space is limited by symbols. What's Your Deadline? How Many Pages? Sign Up and Get Writers' Offers.

Please enter valid email. Back Get Offer. Write my paper. Cite this essay Relative Density. How to Avoid Plagiarism. Not Finding What You Need? Search for essay samples now.Relative densityor specific gravity[1] [2] is the ratio of the density mass of a unit volume of a substance to the density of a given reference material. The term "relative density" is often preferred in scientific usage.

If a substance's relative density is less than one then it is less dense than the reference; if greater than 1 then it is denser than the reference. If the relative density is exactly 1 then the densities are equal; that is, equal volumes of the two substances have the same mass. If the reference material is water, then a substance with a relative density or specific gravity less than 1 will float in water. For example, an ice cube, with a relative density of about 0.

A substance with a relative density greater than 1 will sink. Temperature and pressure must be specified for both the sample and the reference. Pressure is nearly always 1 atm Where it is not, it is more usual to specify the density directly. Temperatures for both sample and reference vary from industry to industry. In British brewing practice, the specific gravity, as specified above, is multiplied by Relative density RD or specific gravity SG is a dimensionless quantityas it is the ratio of either densities or weights.

Relative density with respect to air can be obtained by. Ideal behaviour is usually only seen at very low pressure. For example, one mol of an ideal gas occupies Those with SG greater than 1 are denser than water and will, disregarding surface tension effects, sink in it.

Those with an SG less than 1 are less dense than water and will float on it. In scientific work, the relationship of mass to volume is usually expressed directly in terms of the density mass per unit volume of the substance under study.

It is in industry where specific gravity finds wide application, often for historical reasons.

## Density Formula - How To Calculate Density

The apparent specific gravity is simply the ratio of the weights of equal volumes of sample and water in air:. The density of water varies with temperature and pressure as does the density of the sample. So it is necessary to specify the temperatures and pressures at which the densities or weights were determined.

It is nearly always the case that measurements are made at 1 nominal atmosphere But as specific gravity usually refers to highly incompressible aqueous solutions or other incompressible substances such as petroleum productsvariations in density caused by pressure are usually neglected at least where apparent specific gravity is being measured.

For true in vacuo specific gravity calculations, air pressure must be considered see below. Here, temperature is being specified using the current ITS scale and the densities [4] used here and in the rest of this article are based on that scale.

As the principal use of specific gravity measurements in industry is determination of the concentrations of substances in aqueous solutions and as these are found in tables of SG versus concentration, it is extremely important that the analyst enter the table with the correct form of specific gravity. In the sugar, soft drink, honey, fruit juice and related industries, sucrose concentration by weight is taken from a table prepared by A.

Brixwhich uses SG Given the specific gravity of a substance, its actual density can be calculated by rearranging the above formula:. Occasionally a reference substance other than water is specified for example, airin which case specific gravity means density relative to that reference.

The density of substances varies with temperature and pressure so that it is necessary to specify the temperatures and pressures at which the densities or masses were determined.

It is nearly always the case that measurements are made at nominally 1 atmosphere A material's density is defined as its mass per unit volume.

Put another way, density is the ratio between mass and volume or mass per unit volume. It is a measure of how much "stuff" an object has in a unit volume cubic meter or cubic centimeter. Density is essentially a measurement of how tightly matter is crammed together.

The principle of density was discovered by the Greek scientist Archimedesand it is easy to calculate if you know the formula and understand its related units. For this problem, take a brick of salt measuring To find the density, use the formula, which helps you determine the amount of mass per unit volume, or:. In this example, you have the dimensions of the object, so you have to calculate the volume. Now that you have the mass and volume, calculate the densityas follows:.

One of the most common uses of density is in how different materials interact when mixed together. Wood floats in water because it has a lower density, while an anchor sinks because the metal has a higher density. Helium balloons float because the density of the helium is lower than the density of air.

When your automotive service station tests various liquids, like transmission fluid, it will pour some of the fluid into a hydrometer.

The hydrometer has several calibrated objects, some of which float in the liquid. By observing which of the objects float, the service station employees can determine the density of the liquid. In the case of transmission fluid, this test reveals whether service station employees need to replace it immediately, or whether the fluid still has some life in it. Density allows you to solve for mass and volume if given the other quantity. Since the density of common substances is known, this calculation is fairly straightforward, in the form.

The change in density can also be useful in analyzing some situations, such as whenever a chemical conversion is taking place and energy is being released. The charge in a storage battery, for example, is an acidic solution. As the battery discharges electricity, the acid combines with the lead in the battery to form a new chemical, which results in a decrease in the density of the solution. This density can be measured to determine the battery's level of remaining charge.

Density is a key concept in analyzing how materials interact in fluid mechanics, weather, geology, material sciences, engineering, and other fields of physics. A concept related to density is the specific gravity or, even more appropriate, relative density of a material, which is the ratio of the material's density to the density of water.

An object with a specific gravity less than one will float in water, while a specific gravity greater than one means it will sink. It is this principle that allows, for example, a balloon filled with hot air to float in relation to the rest of the air.

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**Determination of Relative Density of Solid**

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