How many mL is 700 micrograms? - Answers

There can be no equivalence. A microgram is a measure of mass. A millilitre is a measure of volume. The two measure different things and, according to basic principles of dimensional analysis, conversion from one to the other is not valid. If you are not convinced, consider a millilitre of air. How many micrograms? Next consider a millilitre of water. How many micrograms? The masses of equal volumes of the two substances will clearly be very different. So there is no direct conversion between mass and volume: you need to know the density of the substance to enable you to carry out the conversion. Many people believe that there is an exact conversion for pure water: that is not true. It is only an approximation and that has been the case since 1964 when the definition of the litre was changed.