moles to grams?

Question

Can someone please help me figure this out? How many moles are in 4.20 g of Ca(NO3)2?
and SO3? I keep coming up with the wrong answer.

Here are the answers I put in and this is what it said back to me when I submitted it.
(b) Ca(NO3)2
.026
Check the number of significant figures. mol
(c) SO3
.052
Check the number of significant figures. mol

Answer 1

Add the mass of each compound.

Divide 4.20 g by the mass of each to get each answer. It should be a small decimal answer.

Mass of Ca(NO3)2 is:
Ca = 40 x 1 = 40
N = 14 x 2 = 28
0 = 16 x 6 = 96
total = 164

4.20 / 164 = moles

Mass of SO3:
S = 32.1 x 1 = 32.1
O = 16 x 3 = 48
total = 80.1

4.20 / 80.1 = moles

Answer 2

find the molar mass of Ca(NO3)2. You look for the amu on the periodic table for each element. So atomic mass of Ca is 40.08 amu, atomic mass of N is 14.01amu x2 (multiply by 2 since N is in the brackets), O = 16 amu x6 (because 3 oxygen molecules multiplied by 2 is 6), so your total amu is 164.1amu for
Ca(NO3)2 and 164.1amu = 164.1 g/mol so divide the number of grams (4.20g) by the molar mass 164.1

and the number of moles is 0.0256.

same process for SO3

Answer 3

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Answer 4

Calculate the molecular weight of each, and divide 4.2 by each of those numbers. The atomic weights to be used are: Ca, 40; S, 32; N, 14; O, 16.

Answer 5

you may desire to get the molecular weight of the compound in query. Say for water, MW = 18 grams consistent with mole. then, grams water = 18 x a million.9 = 34.2 grams merely examine for the consistency of gadgets.

Answer 6

1/(moleculare mass of Ca(no3)2)*4.2 is the answer

Answer 7

4.2gCa(NO3)2 x 1mole/164g = 0.0256097560975609moles

4.2gCaSO3 x 1mole/120g = 0.035moles