If a hydrate of Na2SO3 is heated to 250 °C, all the water of hydration is lost. On heating a 1.687 g sample of the hydrate, 0.843 g of Na2SO3 remains. How many molecules of water occur per formula unit of Na2SO3?

A 5.00 g sample of hydrated barium chloride, BaCl 2 · nH 2 O, is heated to drive off the water. After heating, 4.26 g of anhydrous barium chloride, BaCl 2, remains. What is the value of n in the hydrate's formula? Solution: 1) Calculate moles of anhydrous barium chloride: 4.26 g / 208.236 g/mol = 0.020458 mol.

Explanation:

atomic number of carbon is 6

electronic configuration of carbon is 1s²2s²2p²

orbital diagram of c is as shown here in the image.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-