The formula that relates the atomic radius (r) to the length of one edge of the cube (s) for
a body-centered cubic cell is 4r= s 3.
s (. nm). nm
3
==4 0 255 0 600
- (C) H 3 PO 4 is a triprotic acid; that is, there are 3 moles of H+ions produced for each mole
of H 3 PO 4 that completely ionizes. Normality is the number of equivalents per liter.
Assuming complete or 100% ionization, a 1-molar HCl solution is 1 normal. A 1-molar
H 2 SO 4 solution is 2 normal, and a 1-molar solution of H 3 PO 4 is 3 normal.
In order to use the concept of normality, one must know the reaction involved. Phosphoric
acid, H 3 PO 4 undergoes three simultaneous ionizations:
H 3 PO 4 + H 2 O EH 3 O++ H 2 PO 4 – Ka1= 5.9 × 10 –3
H 2 PO 4 – + H 2 O EH 3 O++ HPO 4 2-Ka2= 6.2 × 10 –8
HPO 4 2-+ H 2 O EH 3 O++ PO 4 3- Ka3= 4.8 × 10 –13
Because 1 mole of H 3 PO 4 weighs 97.995 grams, 1 equivalent of H 3 PO 4 would weigh^1 ⁄ 3 as
much, or 32.665 grams. Given this relationship, it is now possible to do this problem by
using factor-label techniques.
...
.
mL
mL
liter
liter
equiv
equiv
g
1 g
100 0
1000
1
1
0 100
1
32 665
###=0 327
Part IV: AP Chemistry Practice Test