GCE O Level Chemistry SPA

PROPER FORMAT TO ACE CHEM SPA TITRATION SKILL 1 AND 2

Titration SPA answers

 

Titration no.	1	2	3	4
Final reading/cm3	21.4	20.9	20.6	20.4
Intial reading/cm3	0.0	0.0	0.0	0.0
Volume of P used/cm3	20.4	20.9	20.6	20.4
Best titration results

 

Average volume of P used= 20.9 +20.6+ 20.4

                                                =20.6 cm3

To find no. of moles of Sodium Tetraborate in 1 dm3 of Q Concentration(mol/dm3)

No. of moles of Sodium Tetraborate                

---------------------------------------------------- =  1/2

No. of moles of HCl

------------------------------------------

No. of mols of HCl= Conc X vol (mol/dm3) = 0.100 mol/dm3 X 0.0204 dm3
                                                                             =0.00102

Conc. Of Sodium Tetraborate= No.of mols/vol.
                                                     = 0.00102 mol/0.025dm3
                                                     =0.0408mol/dm3

Conc. Of Sodium tetraborate = 18.5 g/dm3

0.0408 mols =rep 18.5 g  

1 mol rep 18.5/0.0408 = 453.43

Molar Mass= 453.43 g

Conc. In g/dm3 = conc in mol/dm3 X molar mass

18.5 = 0.0408 X molar mass

Molar mass = 18.5/0.0408=453.43

Mr of Na2B4O7xH20 = 23 x 2 +11 X 4 +16X 7 +18X

= 202+18x

202+18x rep 453.43

X= 13.968

= 14.0

 

One key source of experiment error:

The detergent (Solution Q)might contain other impurities, such as other alkalis, hence excessive HCl might be needed.