1991-01-11 — Page 30

年十八國民華中

育教日六廿月一十年午庚厭寳

Commerce (15)

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International Trade.

S.K.Lai

111.Meaning of Visible and Invisible trade, and Balance of Payments

1.Trade can be divided into two types :

a visible trade, and

b.invisible trade.

Visible trade means the imports and exports of physical or tangible goods (such as machinery and foodstuffs) between countries.

Invisible trade means those payments, and receipts and related to the purchase or sales of services rather than that of tangible goods.

Example of invisible trade include

a.freight of shipping or air travel.

b.overseas investments-incomes, such as dividends,

interest W

c.consumable payments of local citizens travelling abroad and

incoming tourists.

diremittances from Hong Kong to Canáda or by foreign. Chinese

to their relatives in Hong Kong.

2.Balance of Payments

In order to assess the financial strenght and position of one's country in relation to overseas countries, we must study: the working of balance of payments,

Balance of payments means the excess of

the amount of money. inflow and outflow of one country. It also means an account. indicating the receipts of foreign money from, and payments

to, overseas governments and citizens,

An unfavourable balance of payments is occurred when the total payments exceed total receipts.

1991 中學會考預習專欄

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Chemistry (15)

LAI

Chemical Properties of HNO,

歷,近照及會 水埗汝洲街88

5.1

1 HND is readily decomposed,

heated or exposed to light

4N02+

2120

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>稚園

及半日幼師 鑽,已受訓士 3483676洽

計員

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brown gas

dissolves in the acid and makes.

it yellow in colour

5.2 Dilute HND is a strong, monobasic

acid. It exhibits

at the usual

properties of acids. However; its reactions with metals are different from those of other typical acids much as dit HCl, diH,SO,, etc.

because dil HNO is an oxidising acid

Only very dilute HNO, behaves as a normal agid when reacted with Mg and: Ca.

e.g. Mg + 2HNO3

+ HA

5.3 Both dilute HNO3 and concentrated

HNO act as strong oxidising

agents. (c.f. conc. H250) because

the nitrate ion (ND, ) in an acidic

medium is an electron acceptor. Conc. HNO

NO," (aq) + (aq)+e.

decreases

Dilute or moderately conc. HNO

NO2" { aq) + 4H*(aq) +3e -—-~NO{g}+2H2O{ @ ) (+5) DN. decreases

(+2)

N.B. The reduction of HNO, is in

fact

complicated. very Sometimes N20, Ny and even NH, are obtained, depending on the strength of the reducing agents, the temperature and the concentration of HNO3,

(a) HNO3,

etc.

dilute or concentrated,

reacts with metals both above and below hydrogen in the Activity Series. Brown gas of NO are seen.

江

次栽種月薪約 履歷及電話致

HNG

Metal

61 號樂善堂王

HNO

neutralization

Metal oxide

{oxidation) +NO & H2O

.. Metal HINO.

師

·e.g. Cu+4HNO

汝。

0號

Metal nitrate

conc.

3Cu+8HNO

dil. or

Metal nitrate NO2+ H2O

- Cu(ND ̧ ) 2 +2H20+2NQ2

÷ 3Cu(NO3)2+41{20+2N0

moderately

conc.

bine

報日僑華

A favourable balance of payments is occurred when the total receipts exceed, total payments.

A balance of payments includes the following three component accounts of international receipts and payments:

a.the current account, which includes visible trade and

invisible trade.

the capital account, which includes long term or short term. capital inflows and outflows, gifts, and grants.

The long term capital funds are channelled into stock market investment and real, investment..

The short term capital flows are usually called "hot money". They are used for speculatory investments. c.the gold and foreign exchange, account, which indicates the inflows and outflows of gold and foreign exchange reserves.

3.8alance of Trade

Balance of trade is the amount of the difference between exports and imports of goods of one country. It shows the. relationship between the balance of visible trade over a particular period of time.

A trade surplus occurs if amounts of exports exceed those of imports.

A trade déficit occurs, if the values of imports are greater than that of exports. However, a trade deficit does not necessarily co-exist

balance :of with an unfavourable payments; the trade deficit can be covered by the surplus in the capital and invisible trade accounts.

4.External Trade of Hong Kong

Hong Kong ranks the top twelve traders in the world market.: China is Hong Kong's largest partner, followed by the United States and Japan.

Statistics of external trade of Hong Kong for 1988-1989 is enclosed in the Figure 1

1.Exports.

The commercial policies and economic conditions of our major trading partners have decisive role in the performance of Hong Kong's export trade.T

metal oxide layer formed on the surface of the metal prevents further attack of. conc. HNO2-

(b) With other reducing agents, conc HNO is reduced mainly to NO (brown gas) and H20.

C+ HNO3 CO2+ ANO, + 24,0

6NO2+ 2H 0

3A

S+

6HN034

2HNO3

SHNO H3PO4 + SNO2 + H2O

H2SO + 2ND2

3Fe+NO+4H

+NO+2H.

low

Dale-

green

2N0+02

cellulose

HNO

6. Nitrates

NO

+heat

HND is monobasic, so, it forms one series of salts, the nitrates.

6.1 All nitrates, except Pb(NO3)2 and

are hydrated.

6.2 Almates are soluble.

6.3 All rates are thermally unstable andy deposed on heating. The ease decomposition increases- down the blyfty Series. Nitrates of Products of

feating metal.

心

Mg

Cozkwa £7

Lead() oxide

Gas H

Ges

Drying agent Hest

Ammonium sulphate:

and Catelum hydroxide

Host

Liguld

(a) Identify and name the substances W,

Kand Y.

(b) Write an equation of the formation e of gas W.

Lead(II) oxeurned from ovand

yellow to reddish-bro

finally to grey - a

五期星日-十月-(一九九一)年十八國民華中(30)

Its largest market was the United States ($72,162 million or

32.2% of all domestic exports), followed by China (19.3%) and the Federal Republic of Germany (7.0%).

2.Imports

Hong Kong is wholly dependable on imported resources so as: to fulfil the diversified needs of its industries and population.

China and Japan were the two leading suppliers of imports in 1989. They occupied 34.9% and 16.6% respectively of the total imports. Taiwan ranked third among the trading partners.

3.Re-exports

The largest re-exports markets were China (29.9%), the United States(20.8%,), Japan (6.4%) and Taiwan (4.8%).

Figura!

Statistics of External Trade.

The Top Third Trading Partners of Hong Kong's

External Trade, (1988-1989)

texpressed in atriton dotars)

First

Second

Third

Merchandise Total

Domastic Exports

Destination United States.

Source

maxports. Destination

Foder al Republic of Germany 1989 72,162 (37.23 43,272 19.35 15.589 17.01) 1988, 72,884 (33.53) 138,043.117.5%). 16,157 (7.411

China

Japan.

faias. 1989 196,676 (34.9) 93,202 (16.6) 51,587, (9.28) 1988155,634 (31.2) 93,008 (18.65) 44,357 (8.9%)

China

"United States. Japan, 1989 103.492 129.95): 12,033-(20.8) 22,268, (6,45) 1980 94,895 (34.5%) 49.483 18.0% 17,419 (6.3%).

China

217;664

562,281

498,798

346,405 -275,405

The figure in bracket shows the percentage of the marchandise total.

dbservation

- KHD ̧ <rystals Solta meitað.

The glowing splint was re- kindlad. Ne 110 crystals Pals-brown times were keen.

The glowing-splint was say kindlad

and.cone.

50

JE. KNO

crystals

concx H2 504

+ copper turnings

1. РЪСНО 2 crystals

Bansa brownies ware 3000.

The glowing splint was extingelsed-

Solld wolted. Brom Tumes,

ene avena'

The giving spifat was sadlad:

(a) Name the gas that re-kindles the glowing splint in experiments I, II and. IVA

圖

(1) What is the grey

obtained?

(2) Write

an

equation

reaction.

b) Write an equation of the reaction

singh.

OF

the

(d)

(d) What property of gas W. is indicated

in the above experiment?.

(e) Name a suitable drying agent for

gas W.

(f) It was found that 36 cm3 of dry gas Y, measured at. 25°C and 1 atm. of pressure, was collected at the end of the experiment.

resi ely..

(e) Which of the two

Pb(NO3)2

heating? Exp]

Question 8.4

gas?

quations of the

II, II and

KNO, and towards

The schematic diagram below shows the. Haber Process by which ammonia is (1) What was the volume of gas manufactured on large scale.

reacted, measured at 25°C and 1| A---- Nitrogen-Purit Tur- atm. of pressure?

| B-- Hydrogen –Für 11ler}-

(2) What was the mass of lead(II)

oxide reacted?

(g) Would there be any reaction if lead(II) oxide is replaced, turn, by

(1) Zntċ(11) oxide,

(2) Copper (11) oxide.

IF NO, state so.

If there is a reaction, describe briefly your observation and write an equation of the reaction.

Question 8.2

KONG BUBLA

e.g.

2P6(NO3)2

На

Metal + NO2+02

Ag

N.T. Thus, an important method of preparing a metal oxides is by heating its nitrates strongly."

6.4 Test for nitrates

(a) If a brown gas is liberated when a solid is heated with a little of conc. H2SO, and copper turnings, then the solid is a nitrate.

NO2 (s) + H2SO2 (1) - HNO3{4}+HSD ̧ ̈(s). 4 HNO3 (®) + Cu(s) — Cu(NO3)2(aq)

+2H2O{8}+2HO2{g}

(b) Mix the unknown solution with freshly-prepared iron(II) sulphate ...in a test-tube. Add conc. 2504

slowly to the mixture down the side of the test-tube so as to form a Tower layer. If a brown ring is formad between. the cone. H2SO layer and the aqueous layer; then the unknown solution consists of NO ions.

-cont.

NO (aq)

Fuso (aq)

"brown ring" Conc. 1,50

hot glass rod.

Oxypan

gas

Glass rod

Pistinta

.spiral

Concentrated

S

trated ich a from a

Konver

ammon

unreacted

N and H 32 [recycled

(a) State ONE possource A of

nitrogen and game

Be the process by which it 1.5 Sprained from its

source.

(b) State Essible source. B of hydrogens and name the process by is obtained from its

(The converter. X is packed with a catalyst. Suggest a suitable catalyst of the reaction.

(d) Suggest TWO suitable methods to

remove ammonia from the device Y,

(e) Nitrogen gas react with hydrogen gas to form ammonia according to the reversible equation below.

N2(g) + 3H2(9) — 2NH2(9);

AH

93kJno)"

(1)

aqueous proɔn la' salution

Is the yield of ammonia bo increased by using a high or low temperature?

drops at iltnus solution

contalaing a few

-function of

the

(a) What is the

platinum spiral? (b) Name the substances formed at the

Platinum spiral.

Write an equation of the reaction. (c) A brown gas is seen near around the

platinum spiral. What is it? Write an equation of its formation. (d) The platinum spiral needs to

heated initially only. Once the reaction is started, no more heating of the spiral is necessary. Explain why this is so.

be

red

(e) The litmus tuns from blue

during the reaction. Explain briefly the changes

observed.

Question 8.3

In the experiment below a substance was heated strongly in a. Pyrex test- tube and a glowing splint was placed in the position as shown.

heat

(1) Is the yield of ammonia be increased by using a high or Tow pressure? (iii) In practic, it is not too high desirable to use a pressure and ล too low temperature in the converter.. Explain briefly your answer in each case.

Solution to Q.8.1 (a) Wis ammonia.

X is water.

Y is nitrogen.

(b) (NH4)2SO4 + Ca(OH) 2

CaSO4+2NH3+2H20

(c) (1) The grey solid is lead.

(2) 2NH + 3Pb0

-3Pb + 3H2O + N2

(d) The reducing property of gas Whis

indicated.

(e) Calcium oxide (quickline).

(F) (1) 2NH3

+ 3PbQ 3PD +

*.: 2mpl 1.e. vol.

+

1 vol.

? cm3

36 cm3

-Glowing splint

N.B. Al or Fe are rendered passive when added to HNO3 because the

Question 8.1

In the experiment below, a colourless liquid X and a colourless gas Y were obtained on passing the gas W over some lead(II) oxide at red-hat.

The following observation was recorded.

." vot. of Nil reacted = 36 x 2

72 cm

(2) M(Pb0) = 223 gol

2011-3

-1

+ 3Pb0

3mol

· 3Pb +

1001

N2

(3x223)

24 cm3

36 cm3

m(Pb() reacted = {3x223)× 24000

1.00 91

(g) (1) NO reaction; because NH, does

reduce ZnO,

hot reb

(2) Yes, there is a reaction.

Copper(IE) oxide

turns

from

black to reddish-brown because

copper is formed."

2NH3

+ 3CuQ

Solution to 0.8.2.

-3Cu + 3H20 7

(a) It acts as a catalyst.

(b) Nitrogen(11)

vapour.

4NH+502

oxide

..and

water

•AND + 6H2O

(c) The brown gas is nitrogen(IV)

oxide.

2N0+

2N0

(d) The reaction occurring at the spiral is exothermic. The heat. evolved can manitzin the spiral at a high temperature..

(e) Ammonia solution is alkaline, so,

it turns litmus blue..

During the reaction, ammonta is reacted while nitrogen(IV) oxide is formed. Nitrogen(IV) oxide is then. dissolved in water to give an acidic solution which thus turnst litmus red.

+

Solution Q.8.3

(a) Oxygen gas.. (b) 2KNO

-2KNO2

HNO2+ HNO3

(c) Nitrogen(IV) oxide. (d) 11: KNO2 + H250

KHSO4 + HNO3 +AND2

III: KNO + H2SO KHSO4 + HNO3 Cu+4HNO — Cu(NO3)2+2NO2+2H20

IV: 2Pb(NO3)2

2PbQ. +

4N02

*

(e) KND, is more stable because it is

decomposed, on heating, to KNO (potassium nitrite) only, not to its oxide.

Solution to Q.8.4 (a) Air

Nis obtained from liquid air by fractional distillation.

(b) Water/Natural gas/Petroleum

industry..

Hy is obtained from water by electrolysis:

(c) Iron powder (with a small amount of

A1203)

(d) NH, is either condensed to liquid NH by cooling or dissolved in water to form aqueous Ni, solution.

(e) (1)

The yield is increased by using a low temperature. Since the forward reaction is exothermic, so, lowering the temperature will shift the .to equilibrium the right, thus giving more NH

(i) The yield is increased by

using a high pressure. Since the number of moles of gaseous reactants is greater. than that of products, so, an increase in pressure will shift the equilibrium to the right. thus yielding more

(iii) It is rather difficult and not economical to build à converter to withstand too large a pressure,

The reaction is too slow at too low a pressure. As a consequence, an optimal

pressure

(~200 atm.) and temperature (450-500°C) is

are employed.

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