What volume of 0.100 M NaCl is needed to react completely with 5.00 mL of 0.200 M Pb(NO3)2?

20 mL

Given data:

Molarity of NaCl = 0.100 M

Volume of Pb(NO₃)₂ = 5.00 mL (5.0/1000 = 0.005 L)

Molarity of Pb(NO₃)₂ = 0.200 M

Volume of NaCl needed = ?

Solution:

Chemical equation:

2NaCl  + Pb(NO₃)₂    →      PbCl₂   +  2NaNO₃

Number of moles of Pb(NO₃)₂:

Molarity = number of moles / volume in L

0.200 M = number of moles / 0.005 L

Number of moles = 0.200 M  ×volume in L

Number of moles = 0.001 mol

now we will compare the moles of NaCl and Pb(NO₃)₂.

                         Pb(NO₃)₂       :            NaCl

                             1                 :              2

                        0.001              :         2/1×0.001 = 0.002 mol

Volume of NaCl:

Molarity = number of moles / volume in L

0.100 M = 0.002 mol / volume in L

Volume in L = 0.002 mol / 0.100 M

Volume in L = 0.02 L      

volume in mL:

0.02 L × 1000 mL/1 L

20 mL