Density is a physical property that describes the amount of mass contained within a given volume. It is calculated by dividing the mass of an object by its volume. Density has various applications in chemistry, such as classifying substances as solids, liquids, or gases, determining if objects will float or sink, and measuring sample purity. Examples are provided showing the higher densities of metals like gold compared to the lower densities of gases and ice floating in water.

1. DENSITY

2. CONTENTS
1. Introduction
2. Definition
3. Unit
4. Calculation of density
5. Relationship between density, mass & volume
6. Importance in chemistry
7. Application
8. Examples
9. Summary
10. References

3. Introduction
• Densityis a physical characteristic used in chemistry to determine how much mass
is present in a given volume of a substance.
• It is a fundamentalconcept in chemistry that allows us to understandthe
relationshipbetween mass and volume.
• It has practical applications in various fields and is a useful tool for scientists to
characterize and analyzesubstances.

4. Definition
- Density is a fundamental concept in chemistry
that describes how much mass is contained
within a given volume of substance.
- Mathematically, it is defined as the mass of a
substance per unit volume.
- Formula:
Density(ρ) = Mass (m) / Volume(V)

5. Figure showing formula of density
Figure showing formula of
density

6. Unit of density
• Units of density include grams per cubic
centimetre (g/cm³)
and kilograms per cubic meter (kg/m³).
• Other units include
(a)pounds per cubic inch (lb./in³)
(b)ounces per fluid ounce (oz./fl. oz.).

7. Calculation of density
How to calculate???
• To calculate density, we need to know the
mass and volume of a substance.
• On substituting the mass and volume of the
substance with corresponding unit the
volume can be calculated easily.
Example
 If a substance has a mass of 50 grams
and a volume of 10 cm³, the density
would be?
Answer:
 Given,
mass(m)= 50g & volume (v)= 10cm³
 ρ= m/ v
 ρ= 50/10 = 5 g/cm³
Therefore, the density would be 5 g/cm³.

8. Relationship between mass volume and
density
Densityis directly proportionalto
mass.
 If volume remains constant, as the
mass increases the density also
increases and vice-versa.
 ρ α m (when volume remains
constant)
Densityis inverselyproportional to
volume.
 If mass remains constant, as the
volume increases the density
decreases and vice-versa.
 ρα1/v (when mass remains
constant)

9. Importance of density in chemistry
Classification of substances
 Density helps to classify materials
as solids,liquids or gases based
on their characteristics.
 By knowing the density the state of
the substance can be predicted.
Figure showing the density of ice with water

10. Identifications of objects
 It can be used to identify unknown
substances by comparing their
densities to known values.
 If density is known the value mass
and volume can be calculated i.e.,
by knowing any two values the
third values can be calculated
easily.
Figure showing different states of
matter

11. Application
• Buoyancy:Density helps us to determine whether an object will sink or float in a
fluid. Objects with lower density than the fluid float floats on fluid.
•
Concentration Calculations: It is used to calculate the concentration of a
solution by relating it to the density of the solvent.
•
Sample Purity: The measurementsof density can indicate the purity of a
sample, as impurities affect the density of a substance.

12. Examples
• Water: If we see the density of water is approximately1 g/cm³ at 4°C. Ice has a lower
densitythan liquid water.

13. Ice floating on water
Gases: Gases have much lower densities than solids
and liquids due to their low mass and high
intermoleculardistances.

14. Metals: Metals like gold and platinum have high densities due to their high atomic
masses and compact atomic structures.

15. Summary
• A volume's density indicates how much mass is contained therein.
• It is expressed in units like g/cm3 or kg/m3 and is calculated as mass dividedby
volume.
• In chemistry,density is used for a varietyof purposes, including substance
identification,classification, quality control, and others.

16. References
• https://www.bing.com/images/search?q=ice+floating+on+water+in+glass&qs=n
&form=QBIR&sp=-
1&lq=0&pq=ice%20floating%20on%20water%20in%20glass&sc=7-
30&cvid=BEFF1612919342C3B97AE2EBFA6C132A&ghsh=0&ghacc=0&first=1&cw=1
499&ch=741
• Goggle , Wikipedia
• NCERT class 10th.