Problems A
199
2 From the given moles of KMnO 4 , calculate the moles of Fe used up The
chemical equation shows that 5 moles of Fe (as FeCl 2 ) are used per mole of
KMnO 4 , so
moles of Fe used up = (8 125 x 10
4 moles KMnOJ (5 "?°
es e
)
V mole KMnO 4 /
= 4 063 x I0~
! moles Fe present
3 From the number of moles of Fe present, calculate the weight of Fe, and
from that the percentage of Fe in the original sample
Weight of Fe present = (4 063 x 10~
3 moles Fe)(5 g £ j
= 0 2267 g Fe
0 2267 g Fe
% Fe present =
—
x 100 = 60 00% Fe
0 3778 g sample
PROBLEMS A
1 Tell how you would prepare each of the following solutions
(a) 3 00 liters of 0 750 M NaCl from solid NaCl
(b) 55 0 ml of 2 00 M ZnSO 4 from solid ZnSO 4 7H 2 O
(c) 180 ml of 0 100 M Ba(NO 3 ) 2 from solid Ba(NO 3 ) 2
(d) 12 liters of 6 0 M KOH from solid KOH
(e) 730 ml of 0 0700 M Fe(NO 3 )j from solid Fe(NO 3 )j 9H 2 O
2 Tell how you would prepare each of the following solutions
(a) 15 0 ml of 0 200 M H 2 SO 4 from 6 00 M H 2 SO 4
(b) 280 ml of 0 600 M CoCI 2 from 3 00 M CoCl 2
(c) 5 70 liters of 0 0300 M ZnSO 4 from 2 50 M ZnSO 4
(d) 60 0 ml of 0 00350 M K 3 Fe(CN) 6 from 0 800 M K 3 Fe(CN) 6
(e) 25 0 ml of 2 70 M UO 2 (NO 3 ) 2 from 8 30 M UO 2 (NO 3 ) 2
3 Find molanties and molahties of each of the following solutions
Solution
(a) KOH
(b) HN0 3
(c) H 2 S0 4
(d) Mg0 2
(e) Na 2 Cr 2 O 7
(f) Na 2 S 2 0 3
(g) Na 3 As0 4
(h) A1 2 (S0 4 ) 3
Density
(g/ml)
1 344
1 334
1 834
1 119
1 140
1 100
1 113
1 253
Weight
pen entage
350
540
950
290
200
120
100
220