The samples of KHCO 3 and K 2 CO 3 were both obtained from ThermoFischer Scientific Inc.. K 2 CO 3 was quoted as anhydrous, 99+% purity. PXRD patterns of the same chemical batch as used for NMR spectroscopy are shown in Figs. . These revealed that the K 2 CO 3 was in fact in the 1.5 H 2 O hydrated form, likely as a result of prolonged air exposure.