SCIENCE FORM 3 CHAPTER 6

Chemical Equations Form 3: Land and its resources A) Proper Properties ties of minera minerals ls a. Most Most mine minera rals ls are are har hard d  b. Most minerals do not dissolve in ater  c. Effec ffectt of of hea heatt on on (i) Metal oxide: "bservation: #loin$ splinter does not li$ht up.

Glowing splinter

Conclusion: Metal o!ide does not decompose hen heated.

Metal oxide

(ii)

Metal carbonate

"bservation: Limeater turns chal%& Conclusion: Carbon dio!ide $as released. Metal carbonate decomposes hen heated.

Metal carbonate

Limewater

Chemical equation:

Metal carbonate

Metal oxide

+

Carbon dioxide

E!amples:

Copper carbonate

Calcium carbonate

copper oxide

Calcium oxide

+

Carbon dioxide

+

Carbon dioxide

(iii)

Metal sulphide

"bservation: Purple acidified potassium man$anate *++) solution turns colourless

Metal sulphide

Conclusion: ,ulphur dio!ide $as released. Metal sulphide decomposes hen Acidifed potassium manganate (VII) solution heated.

Chemical equation:

Metal sulphide

Metal oxide

+

ulphur dioxide

Iron sulphide

Iron oxide

+

ulphur dioxide

Lead sulphide

Lead oxide

+

ulphur dioxide

E!amples:

') (eaction of metals ith o!&$en #lass ool: to prevent the  potassium man$anate *++) cr&stals from mi!in$ ith the metal poder 

Metal powder

!otassium manganate (VII) cr"stals

#lass ool: to prevent the o!&$en $as from escapin$

#unction$ to suppl" ox"gen

Asbestos paper

Chemical equation:

Metal

+

%x"gen

Metal oxide

E!amples:

Magnesium

+

%x"gen

Magnesium oxide

Iron

+

%x"gen

Iron oxide

&inc

+

%x"gen

&inc oxide

C) (eaction of metals ith sulphur 

Metal powder + sulphur powder

Chemical equation:

+

Metal

ulphur

Metal sulphide

E!amples:

Magnesium

+

ulphur

Iron

+

ulphur

Iron sulphide

&inc

+

ulphur

&inc sulphide

Magnesium sulphide

-) Calcium compounds i) (eaction ith acid

'ilute h"drochloric acid "bservation: Limeater turns chal%&.  Carbon dio!ide $as released

Calcium carbonate Limeater Chemical equation: Calcium carbonate ii)

0

&drochloric acid

Calcium chloride

0

Carbon dio!ide

0

Effect of heat

"bservation: Limeater turns chal%&  Carbon dio!ide $as released.

Calcium carbonate

Limewater

Chemical equation:

Calcium carbonate

Calcium oxide

+

Carbon dioxide

/ater 

iii)

Formation of calcium o!ide and calcium h&dro!ide

ichrome wire

Calcium carbonate (limestone)

Calcium carbonate

Calcium oxide

+

Carbon dioxide

'istilled water

Calcium oxide (uic*lime) Calcium oxide

+

Calcium h"droxide

ater

Calcium h"droxide (sla*ed lime) Calcium h"droxide

+

Calcium h"droxide solution

ater

Calcium h"droxide solution (limewater)

Calcium carbonate limestone)

heated

Calcium o!ide  uic%lime)

a little ater is added

Calcium h&dro!ide sla%ed lime)

more ater is added

Calcium h&dro!ide solution limeater)

1uestions: 2 he dia$ram shos an e!periment to investi$ate the reaction beteen pieces of e$$ shell and dilute sulphuric acid.

/hat are the products of the reaction4

5

A

Calcium o!ide 0 carbon dio!ide

B

Calcium carbonate 0 carbon dio!ide

C

Calcium sulphate 0 carbon dio!ide 0 ater 

D

Calcium h&dro!ide 0 carbon dio!ide 0 ater 

/hich of the folloin$ situations ill produce a compound4

Ma$nesium 0 sulphur 

carbon 0 sulphur 

Ma$nesium 0 sulphur 

carbon 0 sulphur 

3

-ia$ram 26 shos the apparatus set7up to investi$ate the properties of compound 1. he $as released turns the limeater chal%&.

-ia$ram 26 /hat is compound 14 A ' C -

Copper o!ide Lead sulphide ,ilicon dio!ide. Calcium carbonate.

Paper 2 1

Figure 1 shows an experiment to study the reaction between iron filings and oxygen. (PMR 2004)

Figure 1 (a) (i) What can you observe happening to the iron filings during the reaction?  

………………………………………………………………………………….

………………………………………………………………………………….  

…………………………………………………………………………………. ( 1 mark )

 

(ii) Give one reason for your observation in (a) (i) …………………………………………………………………………………

 

…………………………………………………………………………………

 

………………………………………………………………………………... ( 1 mark )

  (b) Write the word euation for the reaction.

! ( 1 mark ) (c) "he iron filings in the experiment is then replaced with copper powder. Write the word euation for the reaction.

!

( 1 mark)

#

$iagram % shows the apparatus set&up to study the effect of heat on calcium carbonate. (PMR 2007)

alcium carbonate

W

$iagram % (a) (i) What is liuid '?   ………………………………………………………………………………………………. ( 1 mark ) (ii) What can be observed happening to liuid ' at the end of this experiment?  

……………………………………………………………………………………………… ( 1 mark )

(b) Complete the word euation for this reaction. alcium arbonate

eated

! ( 1 mark )

(c) What conclusion can be made from this study? ……………………………………………………………………………………………………. ……………………………………………………………………………………………………. ( 1 mark ) (d) Suest how slaked lime can be formed from pieces of sea shells. …………………………………………………………………………………………………….. …………………………………………………………………………………………………….. …………………………………………………………………………………………………….. ( # marks )

Paper 2 *o. 1

#

+nswer   a. (i) ,ron fillings burn very brightly. (ii) ,ron filings react with oxygen.

b.

,ron

!

0xygen

,ron oxide

c.

opper

!

0xygen

opper oxide

a

(i) -ime water   (ii) -ime water-iuid ' turns chalky

b

alcium carbonate

c

alcium carbonate when heated releases carbon dioxide that turns the lime water chalky.

d

/y heating the sea shell strongly and then pour few drops of water to it.

eated

alcium oxide

!

arbon dioxide