In: Chemistry
Calculate the volume needed to make 2.20 x 10 2 mL of 0.100 M CaCl 2 solution. What would be the total concentration of the final [Cl - ] alone ?
Given, volume of the solution = 2.2 x 102 mL = 220 mL
= 0.22 L
molarity of the solution = 0.1 M =
0.1 mol/L
Therefore, no. moles of
CaCl2 = molarity x volume in L
= 0.1 x 0.22 L
= 0.022 mol
no. moles = mass/g.mol.wt
mass of CaCl2 = no.
moles x g.mol.wt
=
0.022 mol x 40.08 g/mol
=
0.882 g of CaCl2
Therefore, 0.882 g of CaCl2 is needed to make 220 mL of
a 0.1 M solution.
Hence, we need 0.882 g of CaCl2 and 220 mL of water to make the desired solution.
TO find the concentration of [Cl-] ion alone, we need
to look the formula. One CaCl2 molecule contains 2
Cl- ions.
Therefore, the concetration of [Cl-] ion = 2 x
[CaCl2]
= 2 x 0.1 M
= 0.2 M
hence, the concentration of [Cl-] = 0.2 M