It takes 12.45 milliliters of 0.50 M NAOH to back titrate a mixture containing 1.25 grams of baking soda, NaHCO3, and 10.00 milliliters of 1.2 M HCL solution . Calculate the moles of antacid activity per gram of baking soda.

Respuesta :

Explanation:

First, we will calculate the number of moles of both HCl and NaOH as follows.

     No. of moles of HCl = Molarity × Volume

                                      = [tex]1.2 M \times 0.01 L[/tex]        (as 1 L = 1000 ml)

                                      = 0.012 mol

   No. of moles of NaOH =  Molarity × Volume

                                    = [tex]0.50 \times 0.1245 L[/tex]      (12.45 ml = 0.1245 L)

                                   = 0.006 mol

Therefore, the amount of HCl reacts with [tex]NaHCO_{3}[/tex] will be as follows.

                   (0.012 - 0.06) mol

                  = 0.006 mol

Reaction equation for this reaction is as follows.

       [tex]NaHCO_{3} + HCl \rightarrow HCO^{-}_{3} + NaCl[/tex]

Here, one mole of HCl reacts with one mole of [tex]NaHCO_{3}[/tex] and it forms one mole of [tex]HCO^{-}_{3}[/tex]. Hence, moles of [tex]HCO^{-}_{3}[/tex] is 0.006 mol.

So,  [tex]HCO^{-}_{3} + H_{2}O \rightarrow H_{2}CO_{3} + OH^{-}[/tex]    

Here also, i mole of [tex]HCO^{-}_{3}[/tex] gives one mole of  [tex]OH^{-}[/tex].

So, [tex]OH^{-}[/tex] = 0.006 moles

Now, moles of [tex]OH^{-}[/tex] present per gram will be calculated as follows.

      Moles of [tex]OH^{-}[/tex] per gram = [tex]\frac{0.006 mol}{1.25 g}[/tex]

                              = 0.0048 g/mol

Thus, we can conclude that the moles of antacid activity per gram of baking soda is 0.0048 g/mol.