How Do You Calculate the Molecular Formula of a Gas Compound in Stoichiometry?

AI Thread Summary
To calculate the molecular formula of a gas compound made of boron (B) and hydrogen (H), the empirical formula is determined to be 2BH2, with a molecular weight of 23.6378 g/mol. The weight of the gas sample is 0.596 g, which is not the empirical weight; instead, the empirical weight should be calculated by summing the atomic weights of the elements in the empirical formula. The integer used to derive the molecular formula from the empirical formula is found by dividing the molecular weight by the empirical weight. The discussion emphasizes the importance of correctly identifying the empirical weight to proceed with the calculations.
dracolnyte
Messages
28
Reaction score
0

Homework Statement


a sample of gas compound is made up only of B and H weighing 0.596g occupies 484 mL at STP. *then burned in excess O2, it yields 1.17g of H2O and all of the boron is converted to B2O3
what is a) its empirical formula? b) its molecular weight? c) its molecular formula? d) the weight of B2O3 produced?


The Attempt at a Solution


I kinda have an idea on how to solve this, i answered a) and b), which turns out to be
2BH2 and the molecular weight is 23.6378.

Now, I know that the molecular formula is just the empirical formula times an integer, and that integer is usually the molecular weight of the compound divided by 23.6378.

So i should be getting 0.596g/23.6378g? that doesn't seem right, did i do something wrong here?
 
Physics news on Phys.org
You need to divide the molecular weight by the empirical weight; that gives you the integer you multiply with the empirical formula.
 
Bohrok said:
You need to divide the molecular weight by the empirical weight; that gives you the integer you multiply with the empirical formula.

Ya I know, I have found the molecular weight, but how do i find the empirical weight? isn't it just 0.596g as given?

0.596/23.63?
 
Empirical weight = molar weight of empirical formula.
 
Last edited by a moderator:
0.596 is not molar weight of empirical formula. It is weight of the sample.
 
Last edited by a moderator:
You said you have the empirical formula, so just add up the weight of the elements in the empirical formula.
 

Similar threads

Chemistry Finding the Chemical Formula and Relative Molecular Mass
Replies
13
Views
3K
Chemistry How can I find the molecular formula in this problem?
Replies
10
Views
3K
Chemistry Combustion Analysis- Empirical and molecular formula
Replies
8
Views
3K
Chemistry Finding the molecular formula of an unknown hydrocarbon
Replies
4
Views
3K
Empirical Formula from Stoichiometry?
Replies
2
Views
4K
What Is the Molecular Formula of an Unknown Compound from Combustion Data?
Replies
3
Views
2K
Chemistry Molecular formula of organic compound
Replies
2
Views
2K
Chemistry Molecular mass of gaseous compound question
Replies
6
Views
8K
Question Related To Volume Strength Of H2O2.
Replies
3
Views
6K
Chemistry combustion analysis gas problem
Replies
4
Views
3K

Hot Threads

Recent Insights

Back
Top