this cover unit 19B part 3 .
it up to distinction level
Section 3: Determine empirical and molecular formulae from percentage elemental composition data and mass spectra.
Section 3: Determine empirical and molecular formulae from percentage elemental composition
data and mass spectra.
Introduction:
how to calculate empirical formula
firstly, you convert % to grams.
secondly you divide the grams by the AR of the element to find the mole.
thirdly, divided the moles of each element by the smallest mole.
Fourthly, multiply if needed to make it a whole number.
Describe the molecular ion peak on a mass spectrum
A scientist will use a technique called mass spectrometry if they want to study a molecule. In mass
spectrometry, the molecules are bombarded with special particles that give it a positive charge. This
charged molecule is then called a molecular ion. The molecular ion peak is the highest peak in the
graph.
explain how this can be used to work out molecular formula from empirical formula
you can obtain the molecular formula by dividing empirical formular from the molecular ion peak
molecular ion peak/ MR of empirical formula = molecular formula
Compound P
Percentage Elemental Composition:
Carbon: 92.3% Hydrogen: 7.7%
Empirical Formula calculation:
Step 1
92.3% = 92.3g
7.7% = 7.7g
Step 2
92. = 7.69
7.7/1 = 7.7
Step 3
7.69/7.69 = 1
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller chiam. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £7.16. You're not tied to anything after your purchase.
