Size Dependent Properties

Physical Properties

Used to describe a characteristic of matter you can detect with your senses

It can be observed without changing the identity of the material

All matter has physical properties

Color

Shape

Size

Smell

Taste

Mass

Density

volume

Mass = amount of matter in an object

Volume = how much space matter takes up

Density = amount of matter in a given volume

State of matter

Also a physical property

Depends upon temperature and pressure

Size-Dependent and Size-Independent Properties

Some physical properties can change when the size of an object changes = size-dependent properties (volume and mass)

Length, width, and height are also size-dependent

Density does not change with a change in size = size-independent property

Color and state are also size-independent

Physical Properties of acids and bases

Strength of an acid can be found by finding the pH of the acid

Range from 0 – 14

Above 7 = basic

Below 7 = acidic

7 = neutral

Water is neutral

Acids

Sour taste

Some very dangerous (hydrochloric acid)

Some edible – citric and ascorbic acids – vinegar (acetic acid)

Bases

Ammonia common base used in household cleaning

Soap

Bitter taste

Slippery feel

Chemical Properties

Describes how matter behaves

Characteristic of matter that allows it to change to a different type of matter

Choosing matter

Reactivity is how easily one thing reacts with another

Some metals are unsuitable for jewelry

For example, iron is less attractive and less valuable than gold

It is also highly reactive – it rusts easily

Silver and gold on the other hand have less reactivity, and are better choices for jewelry

Chemical Properties of Acids and Bases

Acids and bases have chemical properties that make acids taste sour and bases taste bitter and feel slippery

Acids

Many acids react with or corrode certain metals

Many acids are edible, but many can also damage plant and animal tissue

Nitric acid and sulfuric acid are found in small amounts in acid rain

Acid rain damages structures and buildings slowly over time

lt can also harm plant and animal life

Bases

A strong base is as dangerous as a strong acid

Sodium hydroxide can damage living tissues

Ammonia can cause nose burns or bloody noses

Size Dependent Properties

Salts

Acids and bases react together sometimes forming salts

Salts are compounds made of metal and nonmetal

Table salt – sodium chloride is the most common salt

Formed from hydrochloric acid and sodium hydroxide

Other salts include

Calcium carbonate = chalk

Ammonium chloride = used in some batteries

Physical and Chemical Changes

Physical change = any change in size, shape, form, or state where the identity of the matter remains the same

Chemical = one type of matter changes into a different type of matter with different properties.

Chemical Changes

New materials are formed

Cannot be reversed easily

Signs of chemical changes include:  release or absorption of energy

Formation of a gas or a solid that is not a result of change of state

Size Dependent Properties

Physical Changes in Nature

Physical weathering is a physical change that is responsible for much of the shape of the Earth’s surface

Soil comes from physical weathering

 Gravity, plants, animals and the movement of the land during earthquakes also cause physicla changes on the earth

Size Dependent Properties

Chemical Weathering

Cave formations form from chemical weathering

Also instances of unnatural chemical weathering – acid rain

Acid rain can chemically weather marble buildings and statues and other outdoor objects.

Size Dependent Properties

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