Question

How many millimoles of Ca(NO3)2 contain 4.78 × 1022
formula units of Ca(NO3)2? The molar mass of Ca(NO3)2 is 164.10 g/mol.
A) 12.6 mmol Ca(NO3)2
B) 13.0 mmol Ca(NO3)2
C) 20.7 mmol Ca(NO3)2
D) 79.4 mmol Ca(NO3)2
E) 57.0 mmol Ca(NO3)2

Answer 1

D) 79.4 mmol Ca(NO3)2

Explanation:

moles of Ca(NO3)2 = Number of formula units Ca/Avagdaro's number

                                = 4.48 × 10²²/6.22 × 10²³

                                = 0.0794 mol

                                = 79.4 mmol ( 1 mol = 1000 millimole)