Balancing a Chemical Equation

How to balance a chemical equation?

A chemical equation tells us the type of reaction between different reactants. Chemical equation gives the states of the reactants and products.  One can calculate the amount of products required for required amount of products.

To balance a chemical equation, very interesting method is algebraic expression method.


for example:  C3H8 + O2 -----> CO2  + H2O



The above reaction is to be balanced using algebraic expressions

step 1) the coefficients of Each reactants and products assumed to be a,b,c,d,...

                    aC3H8 + b O2 -----> c CO2  + d H2O

step 2) identify and count the number of elements on both sides of the reaction

                    carbon: 3a = c

                    hydrogen: 8a = 2d

                    oxygen:  2b = 2c + d

                    

step 3) let us assume a=1, then simplify the equations for other variable values

                        c = 3,     2d = 8   then d = 4             if d=4 and c =3 then 2b=6 + 4 = 10, b=5

step 4) write the chemical equation using the variable values

            C3H8 + 5O2 ---> 3CO2  + 4 H2O



step 5) count the number of atoms on both sides

                   carbon atoms  = 3
                  hydrogen atoms = 8
                  oxygen atoms = 10 




step 6) we conclude that the equation is said to be balanced. 

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Stephen Hawking ....

Stephen William Hawking....great Mathematician, Physicist

Prof. Stephen william Hawking was born on 8th Jan. 1942, in Oxford, England.  Stephen studied at St. Albans School.  Stephen was awarded Ph.D. titled "properties of Expanding Universe" in 1965.  Stephen William Hawking  was an English theoretical Physicist and Cosmlogist.

Important Concept from Stephen William Hawking.......

1. Hawking radiation:

This is the black body radiation which is supposed to be released by blackholes due to Quantum effects.  This leads to black hole evaporation, the meaning is, Hawking radiation reduces the mass and energy of blackholes.

AWARDS :

1. The Adams Prize: The prize is named after the mathematician "John Conch Adams"

2. Eddington Medal: Royal Astronomical society awards the Eddington Medal.  

3. Fundamental Physics Prize: It is awarded by Fundamental Physics Prize Foundation

TOP BOOKS WRITTEN BY STEPHEN WILLIAM HAWKING:

"A Briefer history of time" a famous book written by Stephen Hawking.  A Briefer history of time books gives explanation on all the forces of physics.  

Another book - "The Universe in a Nutshell". 

Stephen is a fellow of the Royal society and he is a member of the US National academy of Science.

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LENS & LENS MAKER'S FORMULA

What is a Lens?

A transparent medium bounded by two surfaces, at least one of the surface should be a curved, is said to be a lens and it is said to be THIN LENS, When there is a small gap between the two surfaces or lenses where the thickness are much less and considered negligible in comparison to the radius of curvature.

LENS MAKER'S FORMULA:

When a lens of refractive index n2 is placed in the medium of refractive index n1, and the radii of curvatures of lens are R1 and R2, then we can write

                     ( n1/v)-(n1/u)  =  (n2-n1)[1/R1  -  1/R2]

dividing the equation by n1,

           we get,   1/v  -  1/u  =  (n2/n1  - 1)[1/R1 - 1/R2]

when the object is at infinity, u = infinity,  and then the image distance v = f, then

lens maker's formula is    1/f = (n2/n1  - 1)[1/R1 - 1/R2]

                                       1/f =(n-1)[1/R1 - 1/R2]



LIMITATIONS OF LENS MAKER'S FORMULA :

- the lens should be thin to consider above formula and the medium is same on either side of the lens.


sign conventions:

for convex lens:

R1 is positive,  R2 is negative and f is positive

for concave lens:

R1 is negative, R2 is positive and f is negative

PROBLEMS USING LENS FORMULA:

1. An object is placed at 8 cm from a lens of  focal length 15 cm, then calculate the image distance and determine whether the image is real or virtual.


2. A student using a lens of focal length -15cm, and object is placed at 20 cm from it, then calculate how far the image is from the lens and find out the magnification.  Conclude whether the image is real or virtual.

3. Calculate the image distance and determine whether the image is real or virtual when an object is placed at 20 cm, from a lens of negative focal length -10cm.

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What is net neutrality?

NET NEUTRALITY.........

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Refraction of light at curved surfaces - do you know?

Refraction of light at curved surfaces.....do you know?

How do you differentiate lens and spherical mirror?

Differentiate focal length and Focus?

Whether pole and optic centre denote same or different?

Differentiate centre of curvature and Radius of curvature?

Can you Identify different types of lenses?

Differentiate beam and ray

Factors effecting focal length of lens

Draw converging beam and diverging beam

What do you term the effective width of a lens through which refraction takes place?

Write lens formula and mirror formula

When do you say an image is magnified or enlarged?

Can you draw ray diagrams for convex and concave lenses?

Can you say convex lens acts both diverging and converging lens...explain 

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REFLECTION AT CURVED SURFACES - PROBLEMS

PROBLEMS IN PHYSICS - REFLECTION AT CURVED SURFACES

PROBLEM 1: 



Where is the image formed when 8 cm tall object is placed at 20 cm. in front of a concave mirror with focal length 5 cm.  Find out the size of the image also.




PROBLEM 2:



A 10 cm tall object is placed in front of a convex mirror of focal length 15 cm, Find out the image distance and write its characteristics .



PROBLEM 3:


10 cm focal length concave mirror is placed at 40 cm, from a wall.  Calculate the object distance such that its image is formed on the wall.



PROBLEM 4:



In front of 15 cm focal length concave mirror, an object is placed at 30 cm, if the object is displaced through 10 cm towards mirror, calculate by how much distance the image is displaced?



PROBLEM 5:



The image is formed behind the mirror, at a distance of 10 cm, when an object is placed at 20 cm in front of it.  Identify the type of mirror used and also calculate the focal length.  

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REFLECTIOIN AT SPHERICAL SURFACES - do you know

DO YOU KNOW? 

 1. Angle of incidence, angle of reflection

 2. Plane mirror, spherical mirrors

3. Normal drawn to plane mirror and spherical mirror

4. Radius of curvature and focal length

5. Relation between R and f

 6. Parallel beam of light

7. Principal axis acts as Normal, discuss

 8. Virtual image and Real image - properties

 9. Situation to get hi=ho in a concave mirror

 10. Characteristics of image formed by convex mirror

 11. Mirror formula - applying to concave and convex mirrors

12. Simplify uv=uf+vf

13. Sign conventions - discussion

 14. The relation between size of image and size of object --> magnification

 15. The relation between object distance and image distance --> magnification

 16. The image formed by convex mirror - explanation

17. Uses of concave and convex mirrors

 18. Working principle of solar cooker

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BENEFITS OF TULSI LEAVES

IMPORTANCE OF TULSI LEAVES....

Tulsi is very important and most prominent herbs in the society.  We use to call the tulsi as 'king of herbs'.  The scientific name of the tulsi is 'ocimum tenuiflorum'.  Tulsi has been cultivated for more than 6000 years.  It is mostly used in Southeast asian countries. Tulsi plant can protect us from many infections.  Let us look at the health benefits of tulsi...

1. ORAL HEALTH:

Tulsi acts as very good mouthwash which can control oral plaque since it has very high antibacterial activity.

2. USEFUL TO PREVENT EYE DISORDERS:

Tulsi leaves protect the eye from free radiacals and environmental damage.

3. VERY GOOD FOR PROTECTING BLOOD VESSELS

Tulsi leaves possess antiinflmmatory and antioxidant properties, it can remove plaque in blood vessels.

4. TULSI CAN INCREASE IMMUNITY

Respiratory disorders like asthma can be treated using tulsi.

5. LIVER CAN BE PROTECTED

6. BLOOD SUGAR LEVELS CAN BE REGULATED


Tulsi can support blood sugar regulation by increasing insulin secretions in type2 diabetes people.

7. PREVENTS KIDNEY STONES

Tulsi helps to reduce uric acid level in the body, it has the property to to clean out the kidneys.

8. SKIN CARE

By consuming tulsi, one can be free skin from all infectios.

9. TULSI PREVENTS PREMATURE AGING

The free radical damage can be reduced by tulsi.

10. EFFECTIVE TO CURE COUGH AND COLD.

Tulsi is considered a sacred plant and it is also used as antiinflammatory and stress reducer.

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Raman Effect - National science day

About Chandrasekhara Venkata Raman (1888-1970)

C.V. Raman was born on Nov.7, 1888 in Trichiopoly (Tiruchirapalli). The Raman's family lived on a low income when Raman was born.  C.V. Raman was awarded both Bachelor and Master's degree before Raman turned 20.

Why National Science Day is celebrated on Feb.28th?

In India, National science day was celebrated first on Feb.28, 1987.  Then onwards we are celebrating National Science Day on Feb.28, this is to mark the discovery on the "Raman Effect" by Indian Physicist, sir C.V. Raman on 28 Feb. 1928.

What is Raman Effect?

While C.V. Raman travelling to Europe in the early 1920s, he noticed that the sea water is in blue color.  This leads to the discovery of the Raman Effect.


Definitions:

I. Change in the wavelength of light that occurs when a light beam is deflected by molecules.

II. Certain molecules cause waves radiation to scatter differently than the other molecules.

III. Raman effect is an inelastic scattering of photon.  Change in the wavelength of light that occurs when a light beam is deflected by molecules.  During  scattering, a very few photons undergo a change in behaviour.

Experiment: When there is an interaction between the particles of  the liquid and the photons to be responsible for the change in the behaviour of the photons.

Why National science day is celebrated on Feb.28?

In India, the first National science day was celebrated on Feb. 28, 1987, then onwards continuously celebrating National science day.  The reason behind it is that to mark the discovery of the "Raman Effect" by Indian physicist sir C.V. Raman on 28 Feb. 1928.

Applications of Raman Effect:


I. NON-DESTRUCTIVE TESTING:  Scientists using the raman effect for analysing the atomic structures of the particles without causing any destruction to the substance.

II. Raman effect - Raman spectroscopy is being used to study the properties of different materials.

III. The chemical constitution of the substances also can be analysed by Raman effect.

DAILY LIFE EXAMPLES:

Why the sky is blue?

As we all know that when light travels in a straight light, and something gets in its path - that may reflect the light, bend it, or scatter it.  By using these known properties we can explain it.

When sunlight passes through the atmosphere, due to the gases & particles present in air, the light is scattered in all the directions.  Sunlight is combination of seven colors, among them, blue is scattered more than the other colors because it travels as shorter and smaller waves.  Blue color is reached to our eyes from all the directions, that is most of the time we see a blue sky. 

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LibfreOffice Calc

Getting started with LibreOffice Calc

What is LibreOffice Calc?  Calc is the spreadsheet component of LibreOffice, generally we use data which is entered in a spreadsheet and then it can be manipulated, to produce required results.  In LibreOffice Calc, one can use different Functions to perform mathematical based calculations, the main advantage of it is, we can convert calc file into different types of files like HTML, pdf, etc.

introduction:

Calc consists of spreadsheets, each spreadsheet is divided into various individual sheets, each sheet consists of cells.  To identify a cell, we should take its row number and column letter.  Each sheet consists of rows and columns.

parts of the Calc:

1) title bar:  The name of the current spreadsheet.  If it is a new spreadsheet, the name would be untitled X. 

2) Menu bar:  It is after the title bar, sub menus will appear in a menu, when we click on it.  The menu bar menus are...File, Edit, View, Insert, Format, Tools, Data, Window, Help, ..

3) tool bar:

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