Unit Unit 1010

Summary Summary checkcheck--

pointpoint

Unit Unit 1010

Summary Summary checkcheck--

pointpoint

Acids & alkalis in daily lifeAcids & alkalis in daily life10.110.1 10.110.1 p.57p.57

1 1 Acids taste ______ Acids taste ______ (a)(a) but alkalis tast but alkalis tast

e ______ e ______ (b) (b) ..

soursour

bitterbitter

2 2 The colour of red cabbage extractThe colour of red cabbage extract

is ______is ______ (a) (a) in acids & ________ in acids & ________ (b) (b) in in

alkalis.alkalis.

redred green green

3 3 Some plant extracts contain pigmenSome plant extracts contain pigmen

ts that can change colour in acids & ts that can change colour in acids &

alkalis. They can be used as _____alkalis. They can be used as _____

_________________ _________________ (a)(a) . .natural indicatorsnatural indicators

4 4 The commonly used laboratory ____The commonly used laboratory ____

_____ _____ (a) (a) include hydrochloric acid, niinclude hydrochloric acid, ni

tric acid and sulphuric acid. The cotric acid and sulphuric acid. The co

mmonly used laboratory __________ mmonly used laboratory __________

(b) (b) include sodium hydroxide & amminclude sodium hydroxide & amm

onia solution. onia solution. 

10.210.2 10.210.2 Laboratory acids & alkalisLaboratory acids & alkalis

alkalis alkalis

acids acids

5 5 We should take the necessaryWe should take the necessary

___________________ ___________________ (a)(a) when when

handling acids & alkalis. We handling acids & alkalis. We must use them carefullymust use them carefully. . 

6 6 Common indicators used in the Common indicators used in the

laboratory arelaboratory are _________ _________ (a) (a) & ___& ___

_______________ _______________ (b)(b) .  . 

litmus litmus

universal indicator universal indicator

safety precautions safety precautions

p.58p.58

7 7 Blue litmus turnsBlue litmus turns ______ ______ (a)(a) in acids. Rin acids. R

ed litmus turnsed litmus turns ______ ______ (b)(b) in alkalis.  in alkalis. 

redred

blueblue

8 8 Universal indicator changes toUniversal indicator changes to

_____ _____ (a)(a) in acids &in acids & ______ ______ (b) (b) in alkalis in alkalis

with a series of colours with a series of colours

in betweenin between.. It is green in colour It is green in colour

in _________ in _________ (c)(c) substances. substances.

redred blueblue

neutralneutral

9 9 The _________ The _________ (a) (a) tells the degree of atells the degree of a

cidity & alkalinity of substances. Tcidity & alkalinity of substances. T

he pH value ranges from_____ he pH value ranges from_____ (b) (b) to _to _

___ ___ (c) (c) ..

>> The pH value of _________ The pH value of _________ (d) (d)

substances is below 7.substances is below 7.

>> The pH value of _________ The pH value of _________ (e) (e)

substances is 7.substances is 7.

>> The pH value of _________ The pH value of _________ (f) (f)

substances is above 7.substances is above 7.

pH scalepH scale

acidicacidic

neutralneutral

alkalinealkaline

141400

10 10 It is important for the different parts of It is important for the different parts of our body to maintain their ________ our body to maintain their ________ (a) (a)

pH levels so that our body can functiopH levels so that our body can function properly. For plants, the availability n properly. For plants, the availability of nutrients depend on the acidity or aof nutrients depend on the acidity or alkalinity of the ______ lkalinity of the ______ (b) (b) ..

10.310.3 10.310.3

Importance of keeping the Importance of keeping the right pHright pH

properproper

soilsoil

11 11 Many daily used products like Many daily used products like cosmetics & personal care products scosmetics & personal care products s

how their ___________ how their ___________ (a) (a) on their pacon their pac

ks.ks.

pH valuespH values

12 12 We can test for We can test for ________________ ____________ (a)(a)

by placing a burning splint at the by placing a burning splint at the

mouth of the test-tube full of the gmouth of the test-tube full of the g

as. It gives out a ‘pop’ sound.as. It gives out a ‘pop’ sound.

10.410.4 10.410.4 The corrosive effect of acids The corrosive effect of acids

hydrogen gashydrogen gas

13 13 Dilute acids react with some metalsDilute acids react with some metals

to give _____________ to give _____________ (a) (a) . The acid. The acid

s are __________ s are __________ (b) (b) to these metals.to these metals.

hydrogen hydrogen

corrosivecorrosive

14 14 Dilute acids also react with building Dilute acids also react with building

materials made ofmaterials made of _______________ _______________

(a) (a) to giveto give _______________ _______________ (b) (b) . . ThatThat

is why acids corrode our buildings is why acids corrode our buildings & statues.& statues.

calcium carbonatecalcium carbonate

carbon dioxidecarbon dioxide

marblemarble

limestonelimestone

sandstonesandstone

15 15 The average pH value of rainwater iThe average pH value of rainwater i

s about s about ______ ______ (a) (a) becausebecause ________ ________

_______ _______ (b) (b) in thein the air can dissolve in air can dissolve in

it . The pH of acid rain is belowit . The pH of acid rain is below ___ ___

___ ___ (c) (c) 。 。

carbon dioxidecarbon dioxide

5.65.6

5.65.6

10.510.5 10.510.5 Acid rain Acid rain ———— the invisible threatthe invisible threat

1616 _________ _________ (a) (a) is formed whenis formed when acidic acidic

gases like _________________ gases like _________________ (b) (b) & &

_______________ _______________ (c) (c) dissolve in the dissolve in the

rainwater. The acidic gases are givrainwater. The acidic gases are giv

en off from factories, power stationen off from factories, power station

s & vehicles.s & vehicles.

sulphur dioxidesulphur dioxide

nitrogen oxidesnitrogen oxides

acid rainacid rain

17 17 The harmful effect of acid rain is The harmful effect of acid rain is

slow but destructive. Itslow but destructive. It _________ _________ (a) (a)

our buildings & statues. It can alsoour buildings & statues. It can also

___________ ___________ (b) (b) in our rivers, lakes in our rivers, lakes

& the sea. It can affect the& the sea. It can affect the _______ _______

__________ __________ (c) (c) by turning the soil by turning the soil

acidic & toxic.acidic & toxic.

corrodescorrodes

destroy lifedestroy life

18 18 We can help reduce air polluWe can help reduce air pollu

tion by using ________ tion by using ________ (a) (a) momo

re efficiently.re efficiently.

energyenergy

p.59p.59

growthgrowth

of plantsof plants

19 19 Acids can be used to Acids can be used to _________ _________ (a) (a)

food because it can stop the food because it can stop the growth of micro-organisms.growth of micro-organisms.

10.610.6 10.610.6 Everyday uses Everyday uses of acids & alkalis of acids & alkalis

preservepreserve

20 20 _________ _________ (a)(a) contains acetic acid acontains acetic acid a

nd is commonly used for food prend is commonly used for food pre

servation.servation.

VinegarVinegar

21 21 Fruits like apple, banana, pear and Fruits like apple, banana, pear and

peach turn brown when they are cupeach turn brown when they are cu

t and left in the air for a period of tit and left in the air for a period of ti

me. Acids can prevent fruits from me. Acids can prevent fruits from __

____________________ (a)(a) 。。browningbrowning

22 22 Acids & alkalis are commonly used Acids & alkalis are commonly used

as as ___________________ ___________________ (a) (a) . For . For

example, hydrochloric acid is used example, hydrochloric acid is used in toilet cleansers, caustic sodain toilet cleansers, caustic soda in oven cleansers and ammoniain oven cleansers and ammonia solution as window cleansers.solution as window cleansers.

cleansing agentscleansing agents

23 23 Acids & alkalisAcids & alkalis _____________ _____________ (a) (a)

each other in a chemical reaction each other in a chemical reaction

calledcalled ______________ ______________ (b)(b) . In . In

this reaction,this reaction, _____ _____ (c) (c) & ______ & ______ (d) (d)

are formed.are formed.

neutralizeneutralize

saltsalt waterwater

neutralizationneutralization

24 24 We can make use of neutralization We can make use of neutralization to solve many daily problems. to solve many daily problems. Examples areExamples are ：：

> > Use ofUse of ___________ ___________ (a) (a) to treat to treat

stomach-achestomach-ache

> > Use of acids or alkalis to treat waUse of acids or alkalis to treat wa

sp, bee, mosquito & ant stingssp, bee, mosquito & ant stings

> > Neutralization of acidic & alkaline Neutralization of acidic & alkaline industrial wastes beforeindustrial wastes before

_________ _________ (b)(b)

antacidantacid

disposaldisposal

25 25 Acids & alkalis should be handled Acids & alkalis should be handled

carefully because they arecarefully because they are _______ _______

________ ________ (a) (a) ..corrosivecorrosive

10.710.7 10.710.7 Safety matters related to Safety matters related to the use of acids & alkalisthe use of acids & alkalis

26 26 ____________ ____________ (a) (a) acid is a solution tacid is a solution t

hat contains a high proportion of ahat contains a high proportion of a

cid in water.cid in water. _____________ _____________ (b) (b) alkali alkali

is a solution that contains a high pris a solution that contains a high pr

oportion of alkali in water. oportion of alkali in water. They are They are

much more ___________ much more ___________ c) c) than dilthan dil

ute acids ute acids & alkalis.& alkalis.

ConcentratedConcentrated

corrosivecorrosive

ConcentratedConcentrated

27 27 Concentrated acids and alkalis giv Concentrated acids and alkalis give out heat one out heat on __________ __________ (a) (a) . We m. We m

ust dilute concentrated acids & alkust dilute concentrated acids & alkalis by adding them to water, but nalis by adding them to water, but not by adding water to them. We muot by adding water to them. We must wear st wear protective clothes, safety gprotective clothes, safety goggles & gloves when doing so.oggles & gloves when doing so.

dilutiondilution

water

concentrated acid / alkali