posted by faye .
how many grans of Ca(OH) are needed to prepare 800.0 ml solution of 0.15M concentration? molar mass of Ca(OH) is 74g/mole
Alright so we want to prepare a 800ml solution of 0.15M concentration.
So first we calculate the amount of Ca(OH)2 **NOTE: SHOULD NOT BE CA(OH) COS +2 CHARGE OF CA2+ IS NOT BALANCED! CA(OH)2 IS A SOLID AND NOT AN ION, HENCE THE COMPOUND CANNOT HAVE AN OVERALL CHARGE. **
Amount (mol) of Ca(OH)2 = M (mol/dm^3) X L (dm^3) = 0.15 X 800.0/1000 (must convert to appropriate units)
Then mass (g) = molar mass (g/mol) X amount (mol) giving you your mass of Ca(OH)2 needed.
Hope I helped! (:
Oops, sorry, my apologies for typing in caps. Was just trying to point that out. :)
...and the answer should only be to 2 sig figs.