One of the chemical controversies of the nineteenth century concerned the element beryllium (Be). Berzelius originally claimed that beryllium was a trivalent element (forming Be 3+ ions) and that it gave an oxide with the formula Be 2 O 3 . This resulted in a calculated atomic mass of 13.5 for beryllium. In formulating his periodic table, Mendeleev proposed that beryllium was divalent (forming Be 2+ ions) and that it gave an oxide with the formula Be 2 O 3 . This assumption gives an atomic mass of 9.0. In 1894, A. Combes ( Comptes Rendus 1894, p. 1221) reacted beryllium with the anion C 5 H 7 O 2 − and measured the density of the gaseous product. Combes’s data for two different experiments are as follows: I II Mass 0.2022 g 0.2224 g Volume 22.6 cm 3 26.0 cm 3 Temperature 13°C 17°C Pressure 765.2 mm Hg 764.6 mm If beryllium is a divalent metal, the molecular formula of the product will be Be(C 5 H 7 O 2 ) 2 ; if it is trivalent, the formula will be Be(C 5 H 7 O 2 ) 3 . Show how Combes’s data help to confirm that beryllium is a divalent metal.
One of the chemical controversies of the nineteenth century concerned the element beryllium (Be). Berzelius originally claimed that beryllium was a trivalent element (forming Be 3+ ions) and that it gave an oxide with the formula Be 2 O 3 . This resulted in a calculated atomic mass of 13.5 for beryllium. In formulating his periodic table, Mendeleev proposed that beryllium was divalent (forming Be 2+ ions) and that it gave an oxide with the formula Be 2 O 3 . This assumption gives an atomic mass of 9.0. In 1894, A. Combes ( Comptes Rendus 1894, p. 1221) reacted beryllium with the anion C 5 H 7 O 2 − and measured the density of the gaseous product. Combes’s data for two different experiments are as follows: I II Mass 0.2022 g 0.2224 g Volume 22.6 cm 3 26.0 cm 3 Temperature 13°C 17°C Pressure 765.2 mm Hg 764.6 mm If beryllium is a divalent metal, the molecular formula of the product will be Be(C 5 H 7 O 2 ) 2 ; if it is trivalent, the formula will be Be(C 5 H 7 O 2 ) 3 . Show how Combes’s data help to confirm that beryllium is a divalent metal.
Solution Summary: The author explains that beryllium is a divalent element with an atomic weight of 9.0u.
One of the chemical controversies of the nineteenth century concerned the element beryllium (Be). Berzelius originally claimed that beryllium was a trivalent element (forming Be3+ ions) and that it gave an oxide with the formula Be2O3. This resulted in a calculated atomic mass of 13.5 for beryllium. In formulating his periodic table, Mendeleev proposed that beryllium was divalent (forming Be2+ ions) and that it gave an oxide with the formula Be2O3. This assumption gives an atomic mass of 9.0. In 1894, A. Combes (Comptes Rendus 1894, p. 1221) reacted beryllium with the anion C5H7O2−and measured the density of the gaseous product. Combes’s data for two different experiments are as follows:
I
II
Mass
0.2022 g
0.2224 g
Volume
22.6 cm3
26.0 cm3
Temperature
13°C
17°C
Pressure
765.2 mm Hg
764.6 mm
If beryllium is a divalent metal, the molecular formula of the product will be Be(C5H7O2)2; if it is trivalent, the formula will be Be(C5H7O2)3. Show how Combes’s data help to confirm that beryllium is a divalent metal.
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Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; Darrell
Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; Darrell