How many moles are in a 111.5 gram sample of sodium chloride, NaCl?

1.91 moles

Explanation:

First you want to find the molar mass of NaCL

Na = 22.99g  Cl = 35.45g

22.99g + 35.45g = 54.44g

Then divide 111.5g by 54.44g and this will give you moles.

i do not get it   at all

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o