REFEREN
育教僑華 M
三張六第日九初月四年戌庚廣夏 WAH KIN YAT: PO
報日橋翠
170英文中學會考試題預習專欄
堅道英文書院主編
化學科
(二十八)
三期星日三十月五年〇七九一曆公 年九十五國民華中
( 接第六張第二頁)
blue
hydrated
anhydrous
文中學會考試題預習專欄
walorine is prepared commercially by the electrolysis of brine. convenient type of call
英文科
(廿八)
王淑方·
in the diaphram call.
JOLUTIONS FOR LAST WEEK
1. Fowdered sulphur and iron Tilings are nized
thoroughly in the theoretical ratio and heated in an evaporating dish. The mixture will glow and become red hot due to exothermic reaction to ferrDUR milohide.
Fe
Fas
The solio mags of ferrous sulphide 18 oroken up into smaller pieces. These are transfered to a flat-bottomed flask fitted with a rubber bunga through whioh pass a thistle funnel and a delivary tube. The delivery tube is led to a pneumatio trough filled with warm water. When dilute hydrochloric acid le poured down the thistle, runnel effervescence occura, and a gas with the smell of. rotten eggs passes through the delivery tube; This gan, hydrogen sulphide, is collected in gas iare by displacement of warm water.
Pos + 2HC1
Combustion
FeCl2
When a lighted splinter is placed at the mouwm of a gaa jar of hydrogen sulphide, the gịa vill burn quietly down the gas jar with a pale blue flame. As there is a limited ampply of air, the combustion is not complete and a yellow deposit of sulphur will form on the side of the har. Drops of water are also found on the side of the jar.
2
28
26
If there is a sufficient supply of oxygen the hydrogen sulphide will burn completely to sulphur diorida and water.
28 S
(b) As a reducing agent
290
When hydrogen sulphide ia passed into a purple solution of acidified potassium parmanganate solution, the latter is reduced, sc
The hydrogen sulphide ia oxidised colourless. to"water" and sulphur yielding a milky yellow suspension..
(0) An un acid
3550 K:50 +250 581
88
Hydrogen sulphide ve passed througn dilute caustic soda solution until no further action. The resulting solution is that of sodium bisulphide.
NaOH + HS - NaES ¤2°
If an equal volume of the same caustic soda solution is added to the sodium m bisulphida solution, a solution of the normal salt, sodium sulphide, will be obtained.
YES + NaOH - NaS+H20
Tast for hydrogen sulphide i Filter paper soaked in lead acetate or Lead nitrate solution, w will turn shiny-black when dipped in a gas-jar of hydregan Bulphide, owing to the formation of lead sulphide.
CH
2CH.
21 (a) Byarogen onioride gasi
NaCl +504 B&HSO
+ NaCl - Na250, + HCl (higher temperature
required)
Nitrie 2014 vapour, the vapour 18 coloured somewhat brown due to decomposition of nitri doid to artrogen dioxide, and oxygen,
NaNO.
BSO
NaHSO RANO
(o) Carbos venozide
H.CO.OH
#20
-.00
HNO
HNO (higher
temperaturə required)
H.CO.OH NaH30 (8,50 as an aoid)
conc. 850 dehydrating agent)
(d) Carbon monoxias and carbon dioxide dioxide
28.30
+30-
as an soid)
4
•• 00 + + CO2 (cono. 8.30 as a
dehydrating.
phis agent).
when cono, sulpauric acid in drepped "on to cane sugar, the sugar gradually turns yellow, then brown and finally a black apongy mass of very pure carbon. Conc. sulphuric acid extracts the elements of water from the Bugar leaving parbon..
- 120 + 11820
1222 11 12
When a drop or two of cono, sulphuric a010 put on to a sheet of white paper, the paper chare. Paper consists of cellulose of formara (C) and the acid extracts the elements
H
10
of water leaving carbon.
g) When cono, sulphuric acid ie dropped on to
blue crystals of copper sulphate, the solid gradually change from blus te white and lose their crystalline shape. CuSO
4.5820
CuSO
ohlorine
rogen
"Graphite anode
Деревтов diaphram
Steel mesh cathode
Steel container
Nauk Solution:
The anoas 18 of caroon and the" cathode inda mash of steal. Two of the producte, sodium hydroxide and chlorine, are kept apart by
a porous diaphram separating the anode and cathode
Cartoonts.
The chloride ions are discharged in preference the hydroxyl ions at the anode and chlorine 18 evolvads
At the cathode, Ayarogen zona are discharged an preference the sodium”ions, and hydrogen is evolved i
Sodium hydroxide 15 formed in the region of the cathode, drips through the diaphram and cathode. and may be collected and concentrated. Reactions of chlorine
(a) When chlerine is passed into potassium iodide
Bolution, the latter turna brown at first. When more chlorine is passed, a black precipitate of
of loding is obtained, 2K1
- 2KCI
When gas jare proniorine and ammonia are placed mouth to mouth, dense white fuses of annondum chloride appeare with loss of the yellowish green colour of chlorine.
Ammonia is firet oxidized by chlorine to nitrogen, where chloriis is reduced to hydrogen chlorida.
301 + SNB, 6NH C1 + 2 7
With excess chlorine, an explosive. compound, nitrogen trichloride. WCI,
Fol wreponierine is passed into purple litnun
solution, the latter first turne red and -in then bleached to a colourless solution. Chlorine dissolves in water forming à sixTUTS of hydrochloric acid and hypochlorous acid which turn purple litmus red. The hypochlorous aoid bleaches red kitmus to a colourlesB. substance.
HC10W
HC1
HCIO
[o]
dj Chlorine reacts with water and 61880ïving in it te hydrochloric and hypochlorous acide. @tanding, the hypochlorous acid slowly decomposes to hydrochloric acid and oxYKSI
28C10
2HC1
when a aizture of equal volumes or chlorine and hydrogen are exposed to direct sunlight, the two gases will combine explosively to hydroge chloride.
ZHC
(f) whòa shlorine i passed over molten sulphur a yellow liquid, disulphur dichloride S2C1, is formed,
29 C12
Coal gas is produced by the destructive distillation of coal. The coal is put into verticalʻāretorts which are heated by producer gas. A mixture of gaseous products is given off. Coke romaine while gas carbon is left as a hard crust on the inside of the retort.
Gaseous products are allowed to pass into the nydraulic main, where coal tar and water condense, They are collected in the tar well,
The impure coal gas is then passed thronga condensers to cool, so that the remaining taz as well as ammonia and water, are collected an a brow liquid. The gas is removed of much of the impurities in the scrubbing towers where the gas in washed with showers of water, Host of the ammonia, sulphur dioxide and some hydrogen sulphide are removed in this way.
The last traces of hydrogen sulphide" aré. removed in the purifiers containing farzio öxide which reaofs with the gas to iron axlphida
@
fe) Swimming was his favourite hobby and
a lot of his time. (occupied)
When you have read this paper, waji you
to a friend? (give it)X
e) His name has been
the list of recommended doctors. (removed from).
(h) The driver.
the bus just in time to
avoid an accident, (stopped)
What I have said may sound incredible, but my friend will.
(tell you the same thing).
(1) Smith has
me
the team. (left) pulled up, struck off, fell through, dropped out of, laid up,"cropped up, backed down, getting at lays out, taken in, pass on, bear out, do away. with, turned out, put out, thought over. cautht up, let down, take away. took up
ENGLISH PAPER
SECTION A
Answer" ALL sections,
Read the following passage careigy and cnen answer the question that follows
Over a century ago it was generally believed that sen could not possibly move mountains or empty seas but we realize how mistaken this belief was when we take a look at the landscape of Hong Kong today.
Right before our eyes in Kowloon Bay is the modern one-and-a-half-mile airport runway, long enough for use by jet aircraft. Vast areas of open land are seen stretching out from both sides of the harbour. One say easily forget that the spacious Victoria Park stands on ground that was not long ago washed by the waves of the sea, and that Hong Kong island's waterfront, which is now one of the main road routes from east to west, and along which there is an incessant flow of traffic, occupies space which was once a part of the sea. AI this is the result of reclamation.
Today we have become so used to seeing large hills reduced to pinnacles of rocks, and harbour inlets replaced by land, that we tend to pay less and less attention to the changes in our landscape that are constantly occurring. With the population of Hong Kong. growing steadily and its industry developing rapidly, we can
be certain that hills in Hong Kong will keep on moving and harbour inlets will continue to be reple ed by dry land. Indeed, it would not be surprising if - very soon had another park like the Victoria Park wnere we can enjoy a quiet walk or a vigorous game of ball
(1) For each of the folowing ring a word of
meaning IN THE PASSAGE
(a) wrong
(b)
scenery
(c)
up-to-date:
stream
made small.
are inclined
taking place
sure energetic
(2) Name three places that have been reclaimed from the
sea
·(3) wr
runway so longt
4) What does a look at the landscape of Hong Kong today tell us about men's engineering ability?
Why is there an incessant flow of waterfront?
along the
(6) What are the two main reasons why it is necessary for Hong Kong to reclaim more and more land?
WILY, WOULU che mi veci aut us supi i seu 11there were soon to be another park Like the Victoria Par
The oxide may be regenerated by blowing a ouvrent of airs
→ 65
The goal gan is then stored in, gan nợiderse It contains approximately 50% hydrogen, 30%- sethane, 8% carbon monoxide, 2% ethylene and small quantities of ather gases.
. Some of the by-products or Goal gas. manufacture are coke, ammoniacal Tiquer and spent oxide. Cora is used as a fuel, for making produced gan,and water gas, and also in the amelting of ores to obtain metale. Ammontacaliquor is mainly used to make the important fertilizer ammonium sulphate. Spent oxide is a sixture of 60% of fras sulphur with ferric oxide, the sulphur in the spent oxide ia used in the manufacture of "ulphuris näida