Science Buddies: "Ask an Expert"

I am currently doing a research project and found some data using the units mmol/m^-3 and umol/L^-1. I have tried finding the conversion for these to either mg/L or PPM but I'm not sure why there is an exponent for them. I searched the measurement and mmol/m and umol/L are the units but am not sure what the exponent is. please help.

Hi,

Thank you for your question!

I want to clarify...is it written as mmol/m^-3 or mmol m^-3 (or umol/L^-1 versus umol L^-1)? Generally, a negative exponent means 1/x. So, the first unit would be millimole per cubic meter, while the second would be micromole per liter. Adding the "/" as well as the negative exponent is ambiguous and the units should be written without the "/" symbol.

I hope this helps! Please let us know if you need clarification or have any other questions.

--Brandi