REACTION of PYREX GLASS with Na,CO, EDWARD POLING
AND
G. R. YOHE
Ohio Wesleren University, Delaware, Ohio
A
S A PART of an experiment with carbon com-
pounds, students in beginning chemistry were asked to heat various carbonates to see whether or not COBcould be driven off. Each test was performed by beating the carbonate in a dry test-tube and conducting any gas liberated into a solution of Ba(0H)z. A number of students reported that they were able to oblam COz from NazCOa in this way. It was suspected that this evolution of COZmight be due to a reaction between the Na2C03and the Pyrex glass test-tube. In order to investigate this possibility, a six-inch length of iron pipe of one-half inch inside diameter, tightly capped at one end, was substituted for the test-tube. The materials heated and the results obtained are tabulated:
Material
Blast Lamp (Dull red heat) (Bright red heat) no CO1 no COI
Bunsen Burner
NanCOa (c.P.) NaaCOa mixed with powdered P m x glass COl evolved NasCOa mixed with powdered common glass no COX
...... small amount of CO%
It is evident from these results that the evolution of COz reported in numerous cases was due to the reaction of the Na2C03 with the glass of the test-tube. I t is also evident that under these conditions the more acidic boro-silicate glass reacts more readily than does common glass with NazC01.
