Cannizzaro copper chlorides

Stanislao Cannizzaro is widely credited with resolving the difficulties and ambiguities about chemical formulas that had prevented chemists from deriving reliable atomic and molecular weights from chemical analyses. Historians of the periodic table credit Cannizzaro with providing one of the pre-requisites of recognizing chemical periodicity, namely a reliable set of atomic weights.

One of the examples in Cannizzaro's influential paper on the subject presented chemical analyses of two compounds of copper and chlorine. Compound A was 36.04% chlorine and 63.96% copper by mass. Compound B was 52.98% chlorine and 47.02% copper by mass.

1) How much chlorine is there for every 100.0 g of copper in compound A? In compound B? Is there a simple relationship between these two quantities? If so, what is it?

2) Use a modern table of atomic weights to determine the empirical formulas of these two compounds.

Reference

Stanislao Cannizzaro, "Sketch of a Course of Chemical Philosophy," Nuovo Cimento 7, 321-366 (1858)
Copyright 2003 by Carmen Giunta. Permission is granted to reproduce for non-commercial educational purposes.

Back to the Classic Calculations home page
Back to the top of the Classic Chemistry site