1968-03-09 — Page 15

CITY HALL

將發僑

飞三第四第

日一十月二年:伏度靈

WAH KIU YAT PO 報 日

六期星

1968

夏僑

『式題預習書調

要蓄

化學科 (十九)

·林錫衡-

毒器 音響

複習題十九

1953英文中學會考試題預習專欄

複習項目 定性分析與鑑別法(三)

地理科 (十九)

▸

劉玉領。

Geography (19)

31. Distinguish between weathering' and 'denudation'

List the chief agents of weathering and tell how. each works.

Weathering refers to the disintegration of rocks by exposure to the atmosphere. The production' of rock-wmste is brought about by various agenta, partly by mechanical bresking and partly by solution and chemical decay. This process invoLYEZ little or no transport of the resulting products,

The products of weathering are removed from their place of formation by the transporting agents. During the transportation, destruction my be done by using the debris an tools, All the destructive processes due to the effects of the transporting agents are described as erosion. Both erosion and weathering co-operate in wearing away the land surface, and their combined effects are described by the term denudation. So, denuda- tion may be defined as the wearing away of the land by various natural agents; it consists of erosion and weathering.

The chief agents of weathering are:

(1) Rain is really a weak acid because it

dissolvas oxygen, carbon dioxide and sulphur dioxide as it falls through the air. Some minerals especially carbonates and ferriferous minerals are dissolved out of rocks by rain water. These rocks are therefore weakened

and begin to break up. This weathering effect of rain water is a chemical one and is most active in limestone rocks and in humid tropical countries.

(2) Temperature change: 'The grast heat of the

sun in daytime, followed by rapid temparatur fall at night, causes rock break-up. During the day, rock surfaces heat up rapidly and the surface layers expand producing cracks parallel to the boulder surface. At night, the same layers contract producing more CHATRI ET 2 henges to the boulder surface. The alternate expansion and contraction days.. the Layera of rock to peel off and fall to the ground under gravity, Rock break-up of this type is called ex-foliation. The process is mainly a mechanical one.

I.

- 白色粉末樣品A,滴以鹽酸生一種能 令石灰水變混濁之氣体B,B是 可能是

A

鹽將此樣品溶液 加入硝酸鎂溶液生白色沉澱C.故是

鹽,C是

種金蛋氯化物之溶液者加氫氧化鈉 溶液则生紅棕色沉澱若加硫氰化, 钾溶液則生成, 溶液呈血红色此物

f

III未知物 加稀硫酸無沉澱產生,原溶液

加濃硫酸與銅片共熱生紅棕色氟体 B. 若加硫酸亞铁溶液再沿管壁注 濃硫 酸則有棕色環呈現。原溶液 氬 化鈉 溶液無沉澱產生但另有 種刺鼻臭之! 無体產生,此氣体C令石蕊試紙呈藍色, A.是.

B是

!

複習題十八解答

I. (1)碳酸鈉與碳酸氫鈉鑑別法~

將欲檢驗之樣品分別配成溶液注入 硝酸鎂溶液若產生白色沉澱則原物 是橼酸鈉無沉澱產生的是碳酸氫鈉. 7. NaHCO2+ Mg(NO3)2 → 2NaNO + Mg(HCG)

Na,CO2+ Mg (NO3), → 2 NaNO2+ MgCO3

(2)氯化鈉,溴化鈉,碘化鈉鑑別法

分别配成溶液,注以氯水及二硫化碳 搅拌震動之若生紅棕橙色液層的原 物是溴化鈉若生紫色液層的原物是 碘化鈉無特殊颜色液層出現的則原 物是氯化的

Nall +

2 NaBry C.→ 2Mall+ Bri (溶于CSz呈

红棕或橙色

2. NaI + Cl2→ zNacl+z(溶于CS2呈

紫色).

HONAKO

13) host action involves the freezing of water, the cracks of rocks during the night and the thawing of the ice during the following day. When water freezes its volume increases. If water in the cracks of rocks freezes a tremendous power is applied to the sides or the cracks. These considerable forɑss looser some of the particles and cause the orsake to wider and deepen, This in time breaks up rocky outcrops into angular blocks which later split into amall fragments. Extensive layers of shattered rock fragments found at the base of a steep slope are know as

(4) Under damp atmospheric conditions, the

oxygen and carbon dioxide in the air combine with substances in the rocke to form oxides, carbonates and hydrates. These are often softer and more easily soluble than the original rocks, and are thus more liable to rook decay.

(5) Plants and animals help in the process of

rock breaking in two ways. Firstly, the roota of planta penetrate into cracks and cause the cracks to widen and the rocks to split eventually, Secondly, by abstracting certain

elements from rock materials, and by the formation of vegetable humus, the plants hastan chemical weathering. Burrowing animals such ar earth-works, help to loosen the soil, so that it can easily be removed by rain or wind.

12. Volcanics, granite and porphyriss are well

represented in Hong Kong. Suggest a mode of formation for each and discuss the effect they szaruiss on relist,

What other rock types are present in Hong Kong? State where they can be found,

作

Folcanics, granite and porphyries are all igneous rocks formed by the cooling of molten

which comes up from below the earth's (at lines or points of weakness, Holten magna into rocks as it cools down and solidifies. the rooks mentioned above differ in mode Gence and grain si no,

rooks are formed when the molter tches the surface, Cooling of Java

quickly before the crystals can form

rule, these extrusive igneous fine-grained or glassy in

plutonic rock which 18

(3) 氯化鉀、氯酸钾鑑別法

分別配成溶液注以硝酸银溶液,若生 白色沉澱的食物是氯化鉀,無沉澱塵 生的是氯酸鉀。

+ AgNO3 →→ KNO2+ AgCI V KClO3+ AgNO3 → KNOG+ AgClO3

日九月三年八六九一般公年七十五國民

Mgs + H2SO2 →→MgSOμ+ H2 $1

H2S + (CH3COO), Pb→2CHkCOOH+ P$ 56

MgSO4+ H2SO4 → X

Mg503+ Hr50μ→ MgSOμ+ H2O + 50%

SQ+(Cryc0036→入 為欲確認最後的一種,可將

生氣悔

高錳酸鉀溶液中,若溶液自紫色 無色且澄清,則可証明所生氯体是 二氧化硫,而確定原物是亞硫酸鹽 5 SO2+2KMnO4+2H2O →

*>SOq+_2M#50y+_2H504)

(5)硝酸鈉,亞硝酸鈉鑑別法

分別加醋酸生紅棕色氣体的是亞硝 酸鈉,否則是硝酸鈉

NaN2+CH3COOH → CH3COONa+HNOL

ZHNO→ H2O+ NO4NO2↑(红棕色) Nano + CH2COCH → CH¿COONa+ HNO,

(HANG加熱才分解)

(6)硫酸,搶酸硝酸鑑別法

分別加硝酸銅溶液,生白色沉澱的真 物是硫酸,其餘二者皆不生沉澱

H2SOù + Ba(NO3), → 2 HNQ,† BaSOμt.

餘下二者另取原液加硝酸银溶液渚生 白色沉澱此沉澱昊光燮紫灰色不溶於 硝酸,但溶於氨水,則原液是蓝酸,不性沉 澱的是硝酸.

HCI + AgNą →→ HNO3+ Agcl_↓

4 AgCl + 2A9.Cl + Cl2

Aged + 2NH4OH → Ag(NAHS&Cl + 2H2O®

離子 Nat K+ Ca SP Bay ac 色黄 紫 磚紅 鮮紅 淺綠 蓝绿

MG FT

-離子

加氯氧化

沉澱颜色

RIPS

LIBRA

(4)硫化鎂硫酸鎂亞祗畈鈃鑑别法

分别配成溶液然後加入稀硫酸若不 生氯体的是硫酸鎂另二者生氣体將 所生氯体通入輔酸鉛溶液中若生黑 色沉澱则該氨体是硫化氢原物是硫 化鎂,不生黑色沉澱的是二氧化硫 物是亟硫酸鎂。

liquid patarial solidifies in large muses within' the crust. The rate of cooling in the interior of the crust being less rapid than that at the

surface, the intrusive igneous rocks so formed aro' coarse-grained. Granite may be found at the surface if the overlying rock strata have been removed by denudation.

Porphyry is a kind of extrusive igneous roci - whose - un guas contains some crystals of plutonie

rooks Formed when the lava was thrown out in the later stages of eruption, bringing out the coarner' crystals from below. It contains large crystals in a fine-grained ground-mas. It is intermediat in physical form between granite and volcanics.

The resistance of granite, volcanics and porphyries to weathering and erosion are all different so that the influence of each on relief varies, Aucng the three porphyries are the hardest and the toughest. They are evenly

jetured and nigh

wee thering givin Tai No Shan and

opography, Sege Are also hig

The

and

stant to erosion and

high rounded mountains, Lantao display such

"group are volcanics which © but subject to weathering. includes the intermediate

jizzed outlines which

part of Hong Kong #Peninsula, Granitɛ

"HOD, S. 5.05

SOL, CI“. PO® NO“

是亞硫酸鋇 Basi

C是二氧化碳 502

故知A 含亞硫酸根離子 SOG 口是氫氧化亞鉄 Fe(OHA

百是铁氰化亚铁Fe[Fe(CN)37元!

A是亞硫酸罐鉄FeSO

IA是氯化银Agcl

B是氯氣Clz

C是氫氧化鈉Ca(OH)

口是氫氧四氣鋼CCA(NHINA(OH)

E是硫化銅Cus

weathering causing disintegration into ̈san!

graine and this in turn loads to the development

of badlands. In granitic regions, comparatively low. hills are frequently witnessed e.g. in the Castle Peak and the Tai lam Chung areae,

Also present in Hong Kong are sedimentary rocks and metamorphic rocks, Sedimentaries including old sedimentaries and recently deposite. alluvium are located in the northeastern parts of the Tolo Harbour, the northwest coast of lantao, the Yuen Long Plain, the Sai Kung District and narrow pockets at the outlet of rivers to the saa. Hatamorphosed rocks are more limited in extent covering the northwestern part of the fuen Long Plain and the southern_banks of the Sham Chi River.

Questions for next weeks,

33. (a) How does ios erode the land surface?

(b) Describe the formation of any three or th

common characteristic features in a glacists, upland region,

(8) In what ways can a glaciated region be OI, VELUS

to mn2

34. Hame two reatures produced by wind erosion and ons produced by wind deposition which frequently occur in tropical deserts, Por each, describe: (a) Lin appearance, and (b) ita formation. Illustra be your answer with diagram

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