Question

Find molar mass of cobalt (II) nitrate ,Co (NO3)2 and determine the number of oxygen atoms in 4.525g Cobalt (II) nitrate.

Please show all work. I do not understand.

Answer 1

1)

Molar mass of Co(NO3)2 = 1*MM(Co) + 2*MM(N) + 6*MM(O)

= 1*58.93 + 2*14.01 + 6*16.0

= 182.95 g/mol

Answer: 182.95 g/mol

2)

mass of Co(NO3)2 = 4.525 g

we have below equation to be used:

number of mol of Co(NO3)2,

n = mass of Co(NO3)2/molar mass of Co(NO3)2

=(4.525 g)/(182.95 g/mol)

= 2.473*10^-2 mol

we have below equation to be used:

number of molecules of Co(NO3)2 = number of mol * Avogadro’s number

= 2.473*10^-2 * 6.022*10^23 molecules

= 1.489*10^22 molecules

number of O atom in 1 molecule = 6

we have below equation to be used:

number of O atom = number of molecules * 6

= 1.489*10^22 * 6

= 8.934*10^22

Answer: 8.934*10^22