Question

How much calcium hydroxide in grams is needed to produce 1.5 l of a 0.25m solution?

Answer 1

The  mass    ca(Oh)2  needed  to  produce  1.5 l  of  0.25 solution  is  calculated  as follows
find  moles
 
=moles   = molarity   x  volume

moles is therefore =   1.5  x 0.25  =  0.375  moles

mass  =  moles  x  molar  mass
0.375mol  x  74.09 g/mol  =  27.78  grams