Answer to Question #151670 in General Chemistry for Q6

Question

A 5.895g sample consist of sodium, , chromium and oxygen, has 1.035 g Na , 2.34g Cr and the unanalyzed ( remaining) is O What is the compound’s empirical formula (Awt of Na= 23, Cr=52, O=16) and name it

Answer 1

We need to first get the percentage composition of the elements

So for Na we have; (1.035÷5.895)×100 which will give 18%

For Cr we have ; (2.34÷5.895)×100 which will give 40%

Since the rest is O so we will have 100-(40+18) which will give 42%

Na Cr O

18 40 42

18/23 40/52 42/16

0.8 0.8 2.6

1 1 3

What we did above was that we first wrote the percentage compositions then we divided them by their molar masses to give us their moles,then after that we divided by the smallest mole to give us the actual values we needed.

So the empirical formula for the compound is;

NaCrO3 and the name is Sodium dichromate.