Faced with inconsistencies in thermodynamic values it is crucial to assess the likely causes of uncertainty and how errors in measured data propagate through the calculations. We carefully considered the pertinent data and reached our conclusion for straightforward reasons which Rai’s commentary fails to address. Most pertinently Rai seems not to grasp the numerical importance of avoiding calculations based on the concentration of Sn4+ in alkaline solutions. It has nothing to do with whether the species is a “bare ion” (sic) or not; it has everything to do with the obvious fact that such exceedingly small values are highly susceptible to experimental uncertainty. This rule is universal and it has been applied to the assessment and processing not just of Sn(IV) experimental data but also data of many other systems including those of Zr, Th(IV), U(IV), Np, and Pu(IV).

Rai’s comments contain various red herrings and misrepresentations. We did not, as claimed, “simply justify”, “make no attempt to resolve”, “simply accept”, “implicitly accept” “completely ignore” or “implicitly consider”. We stand by the judgements we made. They were explained in some detail and they require neither bluster nor re-iteration. It may well not matter what basis species are used in thermodynamic modelling; but only if the calculations can be done without significant round-off and numerical regressions can be performed likewise on error-free data. It is quite wrong to say that there is no way of getting around the problem—whenever appropriate, the algebraic transformations to achieve optimal basis sets are routine in competent practice.

Moreover, we felt no need to belabour the implications of Rai’s conclusion that Na2Sn(OH)6(aq) is un-dissociated in solution. Given the strongly ionic nature of Na+, we are content to leave that to the judgement of this journal’s readership.