presentation ph

8/8/2019 Presentation pH

1/19

TOPIC: pH


2/19

GROUP MEMBERS


3/19

TOPIC: pH


4/19

What is pH

Danish Bio Chemist introduced a scale

that came to be known as pH scale. In

German \p[ stands for \potenz[

meaning \power[. The scale runs from

0 to 14. The pH scale measures how

acidic or basic a substance is. The pH

scale ranges from 0 to 14. A pH of 7 isneutral. A pH less than 7 is acidic. A pH

greater than 7 is basic.


5/19

pH of a solution may be defined asthe negative logrithm (to the base 10)

of Hydrogen ion concentration in

moles/Litre.

pH = log10 [H+]=log1/ [H+]

pH+pOH- =14


6/19

For neutral solution concentration

of [H

+

] ions is equal to OH- ions[H+] =[OH-]

For acid solution

[H+

] > [OH-]For basic solution

[OH-]> [H+]

pOH- =-log[OH-]=log1/[OH-]


7/19


8/19

pH of Some CommonBases


9/19

pH scale - example values

battery acid pH below 1

gastric juice pH about 2

orange juice pH between 3 and 4

milk pH about 6.5

blood

pH between 7.34 and

7.45, very precisely kept

in this range, as the

correct pH is crucial for

the survivalnormal soap pH about 9-10

bleach pH about 12.5


10/19

Measurement of pH of a solution

The accurate value of pH of a solution is measuredby using an apparatus called pH meter.

*The pH can be measured b y the use of universalindicators which are available in the form of pHpapers.

*A pH is a small strip of paper which is coated withindicator.

*An indicator is a chemical which has differentcolours in different solutions.

*T

he nature of a solution is decided by Hydrogenion concentration and its pH value.

*pH papers having different pH range are available.


11/19

UNIVERSAL INDICATOR

Universal Indicator is a homogenousmixture of many indicators. Theuniversal Indicator undergoes a seriesof distinct colour changes as the pHvalues are changed.To know the pH range, a drop ofuniversal indicator is placed on aclean tile and a drop of the test

solution is mixed with it . The colordeveloped tells the pH range of thesolution.


12/19

PH PAPERS

*ApH is a small strip of paper which is coated withindicator.

*The pH paper is prepared by allowing the absorption ofuniversal indicator on blotting papers of best quality .

These papers are dried , cut into small strips andpacked properly. The colour and corresponding pHvalue are indicated on the cover of each packet of

strips of pH papers.

*pH papers having different pH range are available.*To know the pH value, a drop of the test tube solution is

placed on the strip of pH paper . The colour developedtells the pH value of the test solution .


13/19

IMPORTANCE OF

PH IN EVERYDAYLIFE


14/19

Role of pH in causing tooth

decaypH change leads to tooth decay. The whiteenamel coating on our teeth is of Calcium

Phosphate. When pH in our mouth falls below

5.5, the enamel gets corroded .The bacteriapresent in the mouth break down the sugar

that we eat as acid. Lactic acid is one of these.

The formation of these acids causes decrease

in pH . It is therefore advisable to avoidsugary food and also to keep the mouth clean

so that food particles may not be present. The

toothpaste contain in them basic ingredients

help in neutralizing the effect of acid.


15/19

Role of pH in curing

stings by the insects

Bee sting leaves an acid that is known asFormic Acid[Methanoic Acid] whichcauses pain and irritation. The cure s in

rubbing the affected area with a mild baselike Baking Soda and soap. NaOH presentin the soap neutralizes the acid injected in

the body. Similarly, the effect of stings bywasps containing alkaly is neutralized bythe use of Vinegar[Acetic Acid].


16/19

Neutralizing the effect of stinging neetle

(plant)Neetle is a herbaceous plant it is a wildplant and have sharp hairs, which

contain n them Formic Acid if they

happen to touch the body accidentlytheir stings are very painful. The

remedy for the same is provided by

the nature itself. The stung area is

rubbed by the leaves of dock plantswhich often grow besides neetle

plants. These plants inject alkaly

which neutralizes the effect of acids.


17/19

pH in our Digestive System

Our stomach produces Hydrochloric Acid it helpsin the digestion of food without harming thestomach. During indigestion the stomach

produces excess of HCl which causes pain andirritation. To get rid of this pain, people use basessuch as Antacids. These antacids neutralizes theexcess acid. Magnesium Hydroxide a mild basealso known as Milk of Magnesia is often usedfor this purpose. Sodium Hydrogen Carbonateand Aluminium Hydroxide can also be used forthe same purpose


18/19

Soil pH and plant growth The growth of plants in a particular soil is also related to

its pH. Different plants prefer different pH range for

their growth. Soils with high iron minerals or with rotten

vegetation tend to become acidic. Soil pH can reach

upto 4.The acidic effect can be neutralized by liming the

soil by adding Calcium Hydroxide , Calcium Oxide and

Chalk powder. These are basic in nature.

Similarly, the soil with excess of Limestone or

Chalk is usually Alkaline. Sometimes, its pH reaches to

8.3 and is harmful for the growth. In order to reduce theAlkaline effect, it is better to add some decaying organic

matter.


19/19

thank you

presentation ph

Documents