[Mikey15]

How many total moles of ions are released when each of the following samples dissolves completely in water?
(a) 0.35 mol of NH4Cl
(b) 29.9 g of Ba(OH)2·8 H2O
(c) 1.97  1020 formula units of LiCl

I don't know what to do.  If you could just help me with one of these I can probably do the rest.

[ARGOS++]

Dear Mikey15;

It follows exactly the same Recipe, except that on the end you have to count “all” Moles of Ions together:   "Stoichiometry Problem”


Good Luck!
                    ARGOS⁺⁺

[Mikey15]

Ok for B) the 29.9 gram one, this is what I did.  I calculated the molar mass of Ba(OH)2·8 H2O to be 315.444.  Then I divided 29.9 by the molar mass to get .095 moles.  This should be the correct answer but it keeps coming back worn (I do my HW online).  What am I doing wrong?!?

[Mikey15]

sorry meant to say it keeps coming back wrong.

[azmanam]

Write out the total ionic equation for each dissolution.

see here

http://dl.clackamas.edu/ch105-03/dissolut.htm

You have correctly calculated the number of moles of barium hydroxide octahydrate in 29.9g.  But the question wants to know the total number of moles of dissociated ions in solution, not number of moles of starting material.

Show us a balanced ionic equation.  how many moles of barium ions are produced in the dissolution of barium hydroxide?  how many moles of hydroxide ion?