Chemistry 溫習題目 2

2015-06-12 3:00 am

The following table gives some information on three metals P, Q and R and their oxides.

Metal / P / Q / R
Method of storage / Under paraffin oil / In an air-tight container / In a safe container
Colour of metal oxide / White / White / Red

a) Oxides of P and Q give a golden yellow and a brick-red flame in the flame test respectively.
(i) Describe the steps of carrying out the flame test.
(ii) Suggest what P and Q might be.
b) Explain why P has to be stored under paraffin oil.
c) (i) Describe the observations when P is added to cold water.
(ii) Is the resultant solution acidic or alkaline? What is the colour change of the red litmus paper if it is dipped into the solution?
d) A colourless gas forms when Q is added to dilute hydrochloric acid.
(i) Draw a labelled diagram to show how the gas can be collected.
(ii) Suggest a test for the gas and state the positive result.
e) R reacts with oxygen on very strong heating.
(i) Suggest what R might be.
(ii) State ONE use of R.
f) Arrange P, Q, and R in decreasing order of reactivity.
g) Suggest the methods of extraction for P, Q, and R from their metal oxides.

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回答 (1)

polarbearhmh

2015-06-12 4:41 am

✔ 最佳答案

a)

(i)（這個要背出來啊...）
1) Moisten a clean platinum/nichrome wire with concentrated hydrochloric acid.
2) Dip the wire into a crushed sample.
3) Heat the end of the wire strongly with a non-luminous flame.

(ii)
P: sodium
Q: Calcium

b) P reacts with air readily.

c)

(i)
1) P melts to form a silvery ball.
2) It moves quickly on the water surface with a hissing sound.
3) It burns with a golden yellow flame.

(ii)
The resultant solution is alkaline. Red litmus paper turns from red to blue.

d)

(i) http://i.imgur.com/6kVUkw0.jpg
(ii) Test the gas with a burning splint. Hydrogen gas burns with a pop sound.

e)

(i) Mercury
(ii) Make thermometers.

f) P, Q, R

g)

P: electrolysis of molten metal oxide
Q: electrolysis of molten metal oxide
R: direct heating

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