請教幾條 Chem問題

[匿名]

2008-08-06 4:24 am

1. The following substances were burnt in oxygen and the products were mixed with water. Which of these substances would products a resulting solution with the highest pH value?
A. calcium B. Sulphur C. Iron D. carbon

2. A white solid W is dissolved in water to give a colourless solution which forms a white precipitate with barium chloride solution. The precipitate dissolves in dilute nitric acid W is probably
A.K2CO3 B.NaBr C. MgSO4 D.Zn(NO3)2

最好有埋解釋thx!

回答 (1)

理學士

2008-08-06 4:47 am

✔ 最佳答案

1. The following substances were burnt in oxygen and the products were mixed with water. Which of these substances would products a resulting solution with the highest pH value?
A. calcium B. Sulphur C. Iron D. carbon
CaO + H2O ------ Ca(OH)2
其中Ca(OH)2呈鹼性(pH >7)而且最高

2. A white solid W is dissolved in water to give a colourless solution which forms a white precipitate with barium chloride solution. The precipitate dissolves in dilute nitric acid W is probably
A.K2CO3 B.NaBr C. MgSO4 D.Zn(NO3)2
Ba2+ + CO2-3 -------BaCO3 ( white precipitate)
BaCO3 + 2HNO3 -------- Ba(NO3)2 + H2O + CO2

參考: me

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