To convert
mmol"/L"->"percentage"mmol/L→percentage
I assume conversion to w"/v" w/v percentage is wanted here. Since the density of the mixture is not given.
I am converting
mmol"/L"->g"/100mL"mmol/L→g/100mL
So
mmol"/L"=(10^-3xx"mol")/(10^3xxmL)mmol/L=10−3×mol103×mL
=(10^-3xx"mol"xx"molar mass")/(10^3xxmL)=10−3×mol×molar mass103×mL
=(10^-3xx"mol"xxM"g/mol ")/(10^3xxmL)=10−3×mol×Mg/mol 103×mL
=(10^-4xxMg)/(100mL)=10−4×Mg100mL
=Mxx10^-4%=M×10−4% (w/v)
M"g/mol"->"molar mass of the substance"Mg/mol→molar mass of the substance
For 5.4mmol"/L"=5.4xx10^-4M%5.4mmol/L=5.4×10−4M%