A 50.0 mL sample containing Cd2+ and Mn2+ was treated with 64.0 mL of 0.0600 M EDTA . Titration of the excess unreacted EDTA required 16.1 mL of 0.0310 M Ca2+ . The Cd2+ was displaced from EDTA by the addition of an excess of CN− . Titration of the newly freed EDTA required 14.2 mL of 0.0310 M Ca2+ . What are the concentrations of Cd2+ and Mn2+ in the original solution?

the concentration of  in the original solution= 0.0088 M

the concentration of in the original solution = 0.058 M

Explanation:

Given that:

The volume of the sample  containing Cd2+ and Mn2+ =  50.0 mL; &

was treated with 64.0 mL of 0.0600 M EDTA

Titration of the excess unreacted EDTA required 16.1 mL of 0.0310 M Ca2+

i.e the strength of the Ca2+ = 0.0310 M

Titration of the newly freed EDTA required 14.2 mL of 0.0310 M Ca2+

To determine the concentrations of Cd2+ and Mn2+ in the original solution; we have the following :

Volume of newly freed EDTA =

=

= 7.3367 mL

concentration of   =

=

= 0.0088 M

Thus the concentration of in the original solution = 0.0088 M

Volume of excess unreacted EDTA =

=

= 8.318 mL

Volume of EDTA required for sample containing   and    = (64.0 - 8.318) mL

= 55.682 mL

Volume of EDTA required for  = Volume of EDTA required for

                                                                sample containing     and  

                                                              --  Volume of newly freed EDTA

Volume of EDTA required for  = 55.682 - 7.3367

= 48.3453 mL

Concentration  of =

Concentration  of =  

Concentration  of  in the original solution=   0.058 M

Thus the concentration of = 0.058 M

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.