Question

1. tentukan massa molekul relatif dibawah ini
a. Na3PO4
b. (CH3COO)2Ca
c.(NH4)2 SO4
d. Fe2 (SO4)3

Answer 1

A. (3 * Ar Na) + (1 * Ar P) + (4 * Ar O) = (3 * 23) + (1 * 31) + (4 * 16)
  = 69 + 31 + 64 = 164
b. 2[(2 * Ar C) + (3 * Ar H) + (2 * Ar O)] + (1 * Ar Ca)
  = 2[(2 * 12) + (3 * 1) + (2 * 16)] + (1 * 40) = 2[24 + 3 + 32] + 40 = (2 * 59) + 40
  = 118 + 40 = 158
c. 2 [(1* Ar N) + (4 * Ar H)] + (1 * Ar S) + (4 * Ar O)
  = 2[(1 * 14) + (4 * 1)] + (1 * 32) + (4 * 16) = 2 [14 + 4] + 32 + 64
  = (2 * 18) + 96 = 26 + 96 = 122
d. (2 * Ar Fe) + 3[(1 * Ar S) + (4 * Ar O)] = (2 * 56) + 3[(1 * 32) + ( 4 * 16)]
  = 112 + 3[32 + 64] = 112 + (3 * 96) = 112 + 288 = 400