Cliffs AP Chemistry, 3rd Edition

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

75. (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