HKCEE CHEM 2Qs

2007-11-12 3:30 am

89 3b
Action of metal Y on iron(II) sulphate solution : a gas is evolved
Action of heat on Y2O metal oxide : no reaction
(i) What was the gas evolved in the reaction of Y with iron(II) sulphate solution? Write an equation for the reaction involved. (State symbols should be given.)

98 1c
A piece of freshly cut Li metal is placed in air.
(i) What would be observed on the surface of the metal after some time? Write the relevant chemical equation.

更新1:

Metal Y - Adding the Y to water : No observable change - Heating YO : Metal produced When 1.08g of YO is heated strongly, it decomposes completely to give 60.0 cm^3 of oxygen, measured at room temp. and pressure. Calculate the relative atomic mass of Y. (molar volume = 24.0 dm^3)

回答 (2)

[匿名]

2007-11-15 6:48 am

✔ 最佳答案

89 3b…
Y is Hydrogen gas 2Na+2H2O→2NaOH+H2
because…it's oxide is1+…so that we can conclude that it is in group 1…and it can displace the Fe2+,in reactivity series,just K,Na,Ca,Mg,Al,Zn is more reactive than Fe,so that it is Na/K.Since the aqeous solution of FeSO4 present water,the Na/K will react with it.

981c…
it will become grey because of the oxidization of air.
4Li+O2→2Li2O

參考: me

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莫愁

2007-11-16 11:04 pm

89 (3b)(i) hydrogen gas. 2Y(s) +2 H2O(l) → 2YOH(aq) + H2(g).
98(1c)The shiny lithium metal turns dull(無光澤的)after some time. The equation is :4Li(s) + O2(g) →2Li2O(s)
2YO(s) → 2Y(s) + O2(g)
(2) x(0.06÷24) = (1) x(1.08÷molar mass) ,molar mass = 216
I hope you will find them helpful.

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