Question

A 50.0 ml sample of ca(oh) 2 is neutralized by 300.0 ml of hcl solution with a ph of 1.3. calculate the molarity of the ca(oh) 2 solution. 1. 0.50 m 2. 1.0 m 3. 0.05 m 4. 0.30 m 5. 0.15 m

Answer 1

The molarity of the Ca(OH)2 solution is calculated as follows

find the concentration of HCl used from the Ph
that is PH = - log H+= 1.3

H+ = 10^-1.3 = 0.05 M
the moles of HCl = molarity x volume/1000
= 0.05 x 300/1000=0.015 moles

write the reaction equation

that is Ca(OH)2 +2HCl=CaCl2 + 2H20
by use of reacting ratio between Ca(OH)2 to HCl (1:2) the moles of Ca(OH)2 is = 0.015 x1/2=7.5 x10^-3 moles

molarity is therefore = moles /volume in liters

= {( 7.5x10^-3) /50} x1000 = 0.15 M ( answer 5)