function x=mass2x(c)
mNH3=c;  % mass fraction ammonia
mH2=(1-mNH3)*6/34; 
mN2=(1-mNH3)*28/34; 
nNH3=mNH3/17; 
nH2=mH2/2; 
nN2=mN2/28; 
x=nNH3/(nNH3+nH2+nN2)*1;  % mole fraction ammonia












