Chemistry
posted by Tasha .
What is the molarity of a solution of Mg(OH)2 if the solution contains 1.35 g in exactly 100 mL of solution???
A 15.0 mL solution of H2SO3 is neutralized by 12.0 mL of a standradized 1.00M NaOH solution. What is the concentration of the H2SO3 solution??????
What volume of a 1.25M stock solution of NaCl would be needed to make up 250 mL of a .25M NaCl solution

mols Mg(OH)2 = gams/molar mass
Then M = mols/L soln.
H2SO3 + 2NOH => Na2SO3 + 2H2O
mols NaOH = M x L = ?
mols H2SO3 = 1/2 mols H2SO3 (look at the coefficients in the balanced equation.)
M H2SO3 = mols H2SO3/L H2SO3.
Use c1v1 = c2v2
c = concn
v = volume
1.25M*v1 = 0.25*250
Solve for v1 
mols Mg(OH)2 = grams/molar mass
1.35g/58.32
=.0231
m/L solution
.0231/100ml = .00231
????? is that right?