Calculate the hydroxide ion concentration of a 0.200 M solution of HCIO4

The concentration of hydroxide ion is  5   10^ − 14  M.

Explanation:

Consider the equilibrium of this acid's dissociation,

                          H C l O 4  ⇌  H +  +  C l O  4 -

Moreover, let's assume that  H C l O 4  is a strong acid and will fully dissociate.

Hence,

                              [ H + ]  =  0.20  M

Now, recall,  

                  K w  =  [ H + ] [ O H − ]  =  1.0   10 ^− 14

Hence,

                  ⇒ [ O H − ]  =  K w  / [ H + ]  = 5   10^ − 14  M.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

the answer is 303.15 or 303