9. How many grams of CaCO 3 are present in a sample if there are 4.52 x 10 24 at

ID: 824204 • Letter: 9

Question

9. How many grams of CaCO3 are present in a
sample if there are 4.52 x 1024 atoms of carbon in that sample?

Determine the answers to the following on a separate sheet
of paper:

9. How many grams of CaCO3 are present in a
sample if there are 4.52 x 1024 atoms of carbon in that sample?

10. The empirical formula of an unknown substance is HSO4.
If the molecular weight of the substance 194 g/mol, what is its molecular
formula?

11. The empirical formula of an unknown substance is
determined to be CH2. What is its molecular formula if the
molecular weight is 84 g/mole?

12. Nicotine has an empirical formula of C5H7N
and a molecular weight of 162 g/mol. What is its molecular formula?

mass of 4.52*10^24 atoms of carbon=(4.52*10^24)*12/6.022*10^23=90.06gm.

now molecular mass of CaCO3 is=100gm.

12 gm C present in100gm CaCO3.

90.06gm present in 100*90.06/12=750.5gm.

empirical mass=97.

194/97=2

so molecular formula=H2(SO4)2.

similarly for C7H14 and C10H14N2

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