How many grams of sodium chloride decompose to yield 15 grams of chlorine gas? 2NaCl → 2Na+ Cl2
A- 12.363 9 Naci
B- 49.453 g Naci
C- 30 g NaCl
D- 0.846 g Naci

24.6g of NaCl

Explanation:

Expression of the reaction:

            2NaCl →  2Na  +  Cl₂

Given parameters:

Mass of Cl₂  = 15g

Unknown:

Mass of NaCl  = ?

Solution:

To solve this problem, we have to use mole relationships.

 Find the number of moles of the mass of the given specie;

    Number of moles  =  

     Molar mass of Cl₂  = 2(35.5) = 71g/mol

   Number of moles  =   = 0.21mole

Now;

 From the balanced reaction equation;

        1 mole of Cl₂ is produced from 2 moles of NaCl;

      0.21 mole of Cl₂ will be produced from 0.21 x 2 = 0.42mole of NaCl

So,

  Mass of NaCl = number of moles x molar mass

    Molar mass of NaCl  = 23 + 35.5 = 58.5g/mol

 Mass of NaCl  = 0.42 x 58.5 = 24.6g of NaCl

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.