Question

1) A compound with molar mass 110.1 g/mol has the following composition:

C	65.5%
H	5.45%
O	29.1%

Determine the empirical formula

(Express your answer as a chemical formula.)

(Input the elements in your formula in the order shown above. If parentheses are needed in the formula, be sure to include them in your answer.)

2)

A compound with molar mass 110.1 g/mol has the following composition:

C	65.5%
H	5.45%
O	29.1%

Determine the empirical formula

(Express your answer as a chemical formula.)

(Input the elements in your formula in the order shown above. If parentheses are needed in the formula, be sure to include them in your answer.)

3)

Arrange the following substances in order of increasing percent of chlorine.

A.	KCl
B.	BaCl2
C.	SiCl4
D.	LiCl

Enter the letter (A-D) corresponding to each substance.
(least)  <  <  <  (greatest)

Answer 1

1 and 2) Let us assume that there is 100 g of the compound.

Therefore, Carbon = 65.5 g , Hydrogen = 5.45 g and Oxygen = 29.1 %

Firstly let us find the moles for each as--

C = 65.5 g / 12 g/mol = 5.458 moles C

H = 5.45 g / 1. g/mol = 5.45 moles H

O = 29.1 g / 16 g/mol = 1.818 moles O

Let us divide by the smallest value to get the mole ratio---

C:H:O =5.458 /1.818 : 5.45 /1.818 : 1.818/1.818 = 3 :3 :1

The empirical formula will be C₃H₃O.

Now, empirical formula has mass = (3 x 12) +(3 x 1) + (1 x 16 ) = 36 + 3 +16 = 55 g /mol

But the molecular mass is given as 110.1 g/mol. i.e. molecular mass /empirical mass = 110.1 gmol^-1 /55 gmol^-1 = 2

Therefore the required empirical formula will be = 2 x (C₃H₃O) = C₆H₆O₂

3. Mass percent of chlorine = (mass of chlorine / mass of molecule) x 100 %

A . KCl = It contains 1 Cl

So, mass percent of Chlorine =( 1 x 35.45 / 74.5513 ) x 100 % = 47.55 % Cl

B. BaCl₂ = It contains 2 Cl

so, mass percent of chlorine = ( 2 x 35.45 / 208.23) x 100 % = 34.05 % Cl

C. SiCl₄ = It contains 4 Cl

so, mass percent of chlorine = ( 4 x 35.45 / 169.9) x 100 % = 83.46 % Cl

D. LiCl = It contains 1 Cl

so, mass percent of chlorine = ( 1 x 35.45 / 42.394) x 100 % = 83.62 % Cl

The order will be---

B(least) < A < C < D(greatest)