Seasons of the year

The variations of the angle of the plane of the equator to the plane of the orbit of the earth around the sun causes seasons. (And these variations are due to axial tilt). At 22 Dec the plane of the equator (PE) is upper then the plane of orbit(PO). At longest angle. It starts decreasing afterwards. At 22 Mar they are in line. It starts to increase afterwards. At 22 Jun the PE is lower then the PO. At the longest angle. Now it decreases again and again becomes zero at 22 Sept. When the two planes line again.

Electrode potential

Deferentiate mole and gram mole.

Mole and gram mole.

   Mole is a number equal to 6.02×10^23 particals (atoms, molecules or ions ) also called avogadro number. While gram mole is a quantity equal to atomic weight or molecular weight in grams (gram atom or gram molecule). Since 6.02×10^23 particals weigh aqual to atomic weight or molecular weight in grams therefore mole and gram mole are used interchangeably.
eg one mole of water means 6.02×10^23 water molecules. And one gram mole of water means 18 gram water. And 18 g water contains  6.02×10^23 water molecules.

    Atomic/ molecular weight :

The weight of one atom/molecule of a substance is called atomic weight or molecular weight. Its unit is amu or unit less.

       1. Hydrogen. 

           6.02×10^23 H atoms =1.008g
            1                 H atom   = x

            X= 1.008×1/6.02×10^23 =1.67×20^-24 g =1amu

   So the weight of one atom of hydrogen (atomic weight of H) is 1 amu

       2. Oxygen. 

          6.02×10^23 oxygen atoms = 15.9 g
             1            oxygen atom = X

        X =1×15.9/ 6.02×10^23 = 2.64×10^-23 g = 15.9 amu

      (1.66×10^-24 g = 1amu
         2.64×10^-23 g = X
X=2.62×10^-23×1/ 1.66×10^-24 =15.9 g)
        
      So (the weight of one atom) atomic weight of oxygen is 15.9 amu.

       3. Water. 

      6.02×10^23 water molecules = 18 g
            1               water molecule = X g

   X =1×18/  6.02×10^23 = 2.99×10^-23 g
                            ÷1.66×10^-24 =18 amu

  So 18 amu is the weight of one molecule of water ( molecular weight of water.

       pH and gram mole

       For water [H*] = 10^-7 mole/ L or g mole/ L at 25°C
     Since 1 mole of H* = 1 g of H*
     Therefore 10^-7 mole of H* = 10^-7 g H*
   So one L (1kg)of water contains 10^-7 g if H*

    Also for water [OH-]= 10^-7 g mole/ L
    Since one g mole of OH- =17 g
    Therefore 10^-7 g mole of OH- 17×10^-7 g.
So one L (1kg) of watet contains 17×10^-7 g of OH-.
 

Philosophy

STORY -- MAYYONAISE AND COFFEE

When things in your life seem almost too much to handle, when 24 hours in a day are not enough, remember the mayonnaise jar and the coffee!

A professor stood before his philosophy class and had some items in front of him. When the class began, wordlessly, he picked up a very large and empty mayonnaise jar and proceeded to fill it with golf balls.

He then asked the students if the jar was full. They agreed that it was. So the professor then picked up a box of pebbles and poured them into the jar. He shook the jar lightly. The pebbles rolled into the open areas between the golf balls. He then asked the students again if the jar was full. They agreed it was.

The professor next picked up a box of sand and poured it into the jar. Of course, the sand filled up everything else. He asked once more if the jar was full. The students responded with a unanimous "yes."

The professor then produced two cups of coffee from under the table and poured the entire contents into the jar, effectively filling the empty space between the sand. The students laughed.

"Now," said the professor, as the laughter subsided, "I want you to recognize that this jar represents your life. The golf balls are the important things, your God, family, your children, your health, your friends, and your favorite passions - things that if everything else was lost and only they remained, your life would still be full.

The pebbles are the other things that matter like your job, your house, and your car. The sand is everything else the small stuff.

"If you put the sand into the jar first," he continued, "there is no room for the pebbles or the golf balls. The same goes for life. If you spend all your time and energy on the small stuff, you will never have room for the things that are important. Pay attention to the things that are critical to your happiness. Play with your children. Take care of the golf balls first, the things that really matter. Set your priorities. The rest is just sand."

One of the students raised her hand and inquired what the coffee represented.

The professor smiled. "I'm glad you asked. It just goes to show you that no matter how full your life may seem, there's always room for a couple of cups of coffee with a friend."