GENERAL QUESTIONS V 207nesium oxide, Mg + iO 2 —• MgO + 143,400, and the heat of
formation of carbon dioxide, C + O 2 —> CO 2 + 97,650 calories,
and subtract the sum of these quantities: 269,900 — 143,400 —
97,650 = 28,850 calories.
Find in the thermo chemical tables the molal heat of formation
of the carbonates of sodium, potassium, calcium, and barium from
the metal oxide and carbon dioxide, and draw conclusions as to the
relative basic strength of the basic oxides.
- State the colors imparted to a Bunsen flame by vaporized
salts (chlorides) of the alkali and alkaline earth metals. - Give formulas of the peroxides of sodium and of barium.
How do these substances react with cold dilute acids? What is
the formula of the peroxide of potassium? Compare the action
of the oxides Na 2 O, K 2 O, and BaO in water with that of the per-
oxides. What is the valence of the metal in each of the peroxides,
and how do you account for the amount of oxygen over that con-
tained in the oxide?