What is relative molecular mass (RMM) and why use carbon-12?

This is the mass of the atoms in your compound relative to the mass of one atom of Carbon-12 (previously they used Hydrogen-1 or oxygen-16, but these have many naturally occurring isotopes). C-12 is easily measured and has less isotopes than naturally occurring oxygen and hydrogen, so was decided on as the internationally used convention to avoid any miscalculations based on the country research was being conducted in.
It is calculated by the average mass of one molecule divided by 1/12 the mass of a carbon-12 atom

Answered by Alexander P. Chemistry tutor

4201 Views

See similar Chemistry A Level tutors

Related Chemistry A Level answers

All answers ▸

"A chromium compound contains 28.4% sodium and 32.1% chromium by mass, while the rest is oxygen. What is the empirical formula of this compound?"


Without calculation, predict (giving you reasoning) whether the entropy change for the following reaction will be significantly positive, significantly negative or approximately zero: MgO(s) + CO2 (g) --> MgCO3 (s)


The enthalpy of combustion of ethanol is −1371 kJ mol−1 . The density of ethanol is 0.789 g cm−3 . Calculate the heat energy released in kJ when 1 dm3 of ethanol is burned.


In terms of bonding, state the order of boiling point of propane, ethanol and ethanal and why.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2024

Terms & Conditions|Privacy Policy
Cookie Preferences