回應(會考化學)

回應 1

Maryuen:
謝謝化學友的解釋..^^對於這條..我又有一些問題 dil.HNO3和conc. HNO3 + CaCO3是不是仍然會出NO and NO2??其他dil. and conc. acid都會出CO2??conc. H2SO4會出SO2??

化學友:
maryuen，今日答住你部份問題先丫。化學友唸你對conc./dil. HCl, HNO3同埋H2SO4有d混亂，你睇o下下面嘅equations，可能你會clear d:

- metal + dil./conc. HCl --> salt + H2
metal oxide/metal hydroxide + dil./conc.HCl --> salt + H2O
metal carbonate + dil./conc. HCl --> salt + CO2 + H2O

- metal + dil. H2SO4 --> salt + H2
metal + conc. H2SO4 --> salt + SO2 + H2O
metal oxide/metal hydroxide + dil./conc.H2SO4 --> salt + H2O
metal carbonate + dil./conc.H2SO4 --> salt + CO2 + H2O

- metal + very dil. HNO3--> salt + H2
metal + dil. HNO3--> salt + NO + H2O
metal + conc. HNO3 --> salt + NO2 + H2O
metal oxide/metal hydroxide + very dil./dil./conc.HNO3 --> salt + H2O
metal carbonate + very dil./dil./conc.HNO3 --> salt + CO2 + H2O

留意bolded左 嘅equations，睇下幫唔幫到你。

回應 2

Maryuen:
1. maryuen的past paper有問題了..這次是2002..6aii怎麼知道H2O formed is in gaseous state?

2. 有關於electronic diagram..for example..CO2嗯..如果我所有的electrons(both C and O)是用cross的話,ok嗎??

化學友:
1. heat一隻substance通常都唔會太低溫(一般都有百幾2百度)，所以通常H2O exist as a gas。不過化學友記得當時嘅marking接受H2O係(g)或者(l)。

2. OK o架，會考嘅electronic diagram只畫dot或者cross都得。

Maryuen，你都好努力鋤pastpaper wor，繼續add oil啦。