When hafnium metal is heated in an atmosphere of chlorine gas, the product of the reaction is found to contain 62.2 percent Hf by mass and 37.4 percent Cl by mass. What is the empirical formula for this compound?

HfCl3

Explanation:

Step 1

Divide the percent by mass of each element by its relative atomic mass

Hf- 62.2/178.5, Cl-37.4/35.5

0.348, 1.054

Step2

Divide through by the lowest ratio

0.348/0.348, 1.054/0.348

1, 3

Therefore the empirical formula is HfCl3

we need the questions , i may then you.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol