1967-01-04 — Page 15

育教僑華

買三第張四第、

日四十月一

WAH KIU YAT P

育教僑華

英文中學會考試題預習專欄

物理科

(土)

•

梁海明,

PHYSICS I 10) H.M.Leung...

Solution.

17.(a) The specific heat of any material is the quan- tity of heat necessary to raise the température

of 1 gm. of it through I deg. (Unite: Cal/gm/deg Or, the specifio heat of any material is the quantity of heat necessary to raise the tem→→ perature of 1 lb. of it through 1 deg.ff Units: B.Th.U./lb./deg.F).

The water equivalent of any body is the mess of water which has the same thermal capacity. as the body.(Units: gm or lb.)

Thermal capacity of any boty is the quantity of heat necessary to raise its temperature by 1 deg. ( 1 deg.F)

(b) Let V be the volume of the two vessels

M be the mass in gm of the iron vessel Mbe the mass in gm of the copper vessel, then M 7.97

M=8.97

let Q be the thermal capacity of the bron vessel

be the thermal capacity of the copper, veesel

cal.per deg.C

··20-0.09x=0.09x8.9V cal.per deg.C but the water equivalent of each vessel is nu- merically equal to the thermal capacity of the vessels,

then Q1-0.12:01-0.12x7.9V

if W, is the water equivalent of the iron vessel and W is the water equivalent of the copper vessel,

- Q.12x7.97 : 0.09x8.9V 1

WEW

Answer: The ratio or water equivalents or the

iron vessel to the copper vessal 19% 1.18 1.

(c) Heat absorbed by the solid. Heat given out

water and flesk", Heat given out by water and flask

(200+10)(16-14.5) cal.

10 x 1.5

315

bal.

cal.

Ingwer: 315 cal. was absorbe

dissolved..

80112

18.(a) The latent heat of steam is the quantity ot

heat required to change 1 gm. of water from the liquid to the steam state without change of temperature,

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英文中學會考試題預習

化學科

CHEMISTRY (10)

(+)

•

王鋪釘。

Q.1(a) Permanent harduess in water is baysed by thiệ

presence of dissolved calcium and magnesium, salts other than their bicarbonates,e.g calcium sulphate and wagnesium chloride. When a sample of water which is only temporari ly hard is boiled, the soluble calcium anë

agnesium "salts are gonverted into insoluble) salts, and the water is softened.

calcium

(soluble

Calcu

bicarbon iden

(insuf

The Lime soda Process Te (b)A process for softening water

permanently and temporarily hard.

All the temporary hardness is removed: byž audition of the currect quantity of slai Time Slaked lime converts, soluble calciu bicarbonate into insoluble calcium carbonite.

Ca(on) 2Caco

21120 Magnesium bicarbonate is converted first lo magnesium carbona

then to the less~ soluble magnesium hydroxide,

+

*

Ca(Ull){ « MgCO3! +CaCU2! +il, U

Me Co. Caful)

The calcium carbonate, and magnesium hydroxide are removed hy

Sodium carhowitej Le the permanent

also added coep

CaCO

egCO.

Na Su

Thus both temporary and permanent nardness. are removed by the addition of the correct

itities 0 line and soda. (c)Volume of soap solution needed to produce a

permanent Tather with 25 s.o.of distilled valer

HON KON

The Latent heat or fusion of foe is the quan- tity of heat raquired to convert 1 gm..of los from the solid to the liquid state without change of temperature.

specific heat of metal - 0,13

mass of water

initial temp. of metal

Pomaga of water.

initial temp. of water -

W21

7100 100

temperature of mixtúre 10 0

mase of remaining water and metal

1200

(1) To find the heat lost by the metal

Let Qcal, be the heat lost,

- 21 x 0.11 x (710-1073m25 - 1617

cal/gm/deg.0,

(11) Beat gained by the remaining water

be the heat gained by the

water,

Caneta

--( 120–21 )x1x(10–0)

99 3/10

990

1131) To find the latent heat of steams

KHUJO OS-Water-changed inte ataan

100-99.

QURKISTY OF neat used to change 1 gm.

from 0°C to stealm 99028

oal:

2 100+ latent heat of steam batent hons of ateam » 627–100 cal/gm

527

sal/gm lest by the metal

990 chi in gained by the remain

igures give 527 cal per

(mean given ous by steam

heat

80x100

the latent heat of steam; gm. at 100°c required.

100

200

200

end/gmi

absorbed by icer beat absorbed by water

absorbed by calonímeter.

10-0) +200x0,i={10-0)081 ;).

200

Volume

perua

808p Borution needed "to"produce@ latter with 25 ce of tap

Theruoiling, remov

water relative to distille

三期泉

姓名如下:俄浦、

期歌出同治、褲裝、

年詞,白夫人雪 典禮,由約翰食替致

磨著有官排名,

日四月一年七六九一度公年六十五國民中

DESGESE

62-2014

長作悴務慢告,白

[姊夫人發熱踞 I

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論,診勵,產生

長英醤俊喦徒事結

「生共八十三名,因会 姓名保英文,不再

聖士提反女校畢業禮

+ BEKENNTNI

主過戶女模於昨日正

(#)SHREKAN-EUROSSRE•

白約翰會督致訓詞 白夫人頒發畢業證書

(N)CONDEINK<BASSEPTER

HILE LEES (HERE)

«ECHA

Hence

Te :water 10

·

14.5

hardness: Permanent

20 : 29 wana

----(6)

(the):

3.2(a) Soaps are the sodium or potassium salts of

fatty acids If an oil or a fat such palmitic acid, stearic acid or oleic acid is boiled with caustic soda solution, the glycerine is separated from the "fatty acid which is left) as the sodium salt, viz.,godium palmitate,

_C00 Na, CUO Na: sodium stearate, C, H, 1531

1735 or sodium oleate, 1733

C

COO Na. The soap is

"salted out" by the addition Common sait, and the soap, when cool, Bets as a hard the surface of the liquid mixture

es.8 18 called saponification,

+

caustic

tristearate Boda

glyceryl

(fat}

sodium stearate

cake or

This pro

+"glycering

(soap).

(b) Soaps normally used for cleansing purposes are).

Soap dissolved in water

soluble in water. lowers

80

that

P surface tension of water, and iş i therefore able to wet greasy surfaces, small quantities of bil may be rinsed off the surface of plates and dishes

Wien; the article to be vaslied is placed in the soap solution, the hydrocarbon chains in the soap are attracted towards the oil or the grease because they are soluble in oil. They ection of shaking or scrubbing dislodges the dirt (011 or grease) from the surface, the dir being held in solution until, it is eventually rinsed away.

(Synthetic detergents are not the sodium salts of fatty acids, but are sulphonic-acid sodium salts, eg,aodium hexadecylsulphate CH-50-Na-they are chemicully very similary

16:33 3

to ordinary salts -synthetic detergents, howeve have the advantage over soap that

that they are more Efficient because less is reluired, and thin

their calcium salts are solubie in

water wnet detergents are used in hard water A no seuw_is_produced as is the case wher

Đạp in used. Solid fuels - coke, anuliracite Liquid fuels:- Kerosene gasoline

oline uaseous fuels:-coal gas butane

Use

Allotropel

(ajŲinmond

ZBLIC LIBRA

nese in the wateứng

Il chertemporaryThard?

Vol of soap solution needed to produce a permanent lather with 25 c.c.of tap water after boiling = 0.2 0.c.

Fermanent hardnessgin to water relative

[vateri

0.4

of soap-solution that would be required ve the temporarylbarduess_is_2500_of_tua

10.6-6.210.0/

Temporary, la sctness in the water relative kordistilld

a

Ana

butchêat given out by steam

540m + 90m,

540xm+mx(100–10)

630m

630m 11200

17.8.

cal

cal

oal

of: team at 1000 18 required.

Topics for revisien this week:

1. Boiling and melting points and the influence of

pressure on them

A qualitative treatment ur bygromatry, humidity,, dew point.

Questione.

19,(a) Explain brieri, how you could find the dev

point of absitito

with very staple ep-

(8)

b)Graphicë (é)Wood_charcoal

{{d}Animal【charcoal}

(e) Lampblack

Jused 10 cutting Instrument such as glass-cutters, and drill points

used as a lubricant” used as an absorbent for! gases including air

(used for removing colouring!

matter from solutions

'QUESTIONS FUR"NEXT WELD

used to make printer te

and black shoe-polish

1 Describe how you would prepare and coliceo coruna)

monoxide free from carbon dioxide

llow and under what conditions does carvun mun- oxide react with (s) blood; (b) cuprous chloride, (c) steam; (d) oxygen; and (e) cupric oxide?o 25 Under what conditions and with what results Queey

coke react with (a) carbún dioxide; (b) water (e) a limited supply of air; and (c) sulphur? What is water gas? Describe how it is manufacturea and state its importance,

*

Explain how hydrogenäis made commercinity: from water gas

When coal gas is prepared-

(a)in what is the coal pul and yow 1971t heated? (b)What is left after all the gas has been driven

What purities areštuTMule¥gás?! (a)How are these rapurifies removed?

}Name, onetuse, für each of the

from the us

paratas.

(b) State two ways in which

:ities removed

aiskreta

vapour

differs from an unsaturated vapour {) Define relative humidity and explain how

measure them for the air of a room.

20.Describe how the following can be demonstrated

(a) a vapour exerte a pressure.

(6) This pressure is a maximum when the vapoE,

ie Baturated,

(a) The maximum vapour pressure is independent

of the volume occupied by the vapour. What 18 meant by the boiling point of liquid? How does boiling differ from empre ation?

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