Chemistry Changes in Matter
Chemistry
Changes in Matter
16
Objects made of iron rust when exposed to the air. Moth balls become smaller in
size when kept exposed to the air. Ice melts and turns into liquid water. We have
seen changes in matter like these. To study them further let us do the activity 16.1
given below.
Activity - 16.1
Requirements : A piece of magnesium (Mg) ribbon, about 50 ml of dilute sulfuric
acid (H2SO4), a few pellets of sodium hydroxide (NaOH), two metal spoons, a
moth ball (naphthalene), a box of matches, two 50 ml beakers, a Bunsen burner, a
thermometer
Do the activities (i), (ii), (iii) and (iv) and record the observations.
i). +HDWDPHWDOVSRRQVWURQJO\LQWKH%XQVHQÀDPHDQGWDNHLWDZD\IURP
WKHÀDPH3ODFHDPRWKEDOORQLWDQGREVHUYH&ORVHLWZLWKDQRWKHU
spoon quickly. After some time observe the inner side of the spoon.
ii). Hold a piece of cleaned magnesium ribbon with a pair of tongs and burn
it.
iii). Measure the initial temperature of a dilute sulfuric acid solution. Add a
few pellets of sodium hydroxide to this solution, stir and measure the
temperature again.
iv). 3XWDSLHFHRIPDJQHVLXPULEERQWRDEHDNHUFRQWDLQLQJGLOXWHVXOIXULF
acid.
See whether the observations you obtained through the above activities conform to
the following.
i). Moth ball melted and vaporized. A white powder deposited on the inner side
of the spoon.
ii). 0DJQHVLXPULEERQEXUQHGZLWKDZKLWHEULJKWÀDPHOHDYLQJDZKLWHSRZGHU
iii). Sodium hydroxide dissolved. The container became hot. The thermometer
reading rose.
iv). Magnesium ribbon dissolved liberating gas bubbles. The beaker was heated.
86 For free distribution
,Chemistry Changes in Matter
In case (i) above solid naphthalene melted and then turned into a vapour. On the cold
VXUIDFHRIWKHVSRRQWKHYDSRXUVROLGL¿HGIRUPLQJDWKLQVROLGOD\HURIQDSKWKDOHQH
When solid naphthalene melted, liquid naphthalene vaporized and naphthalene
YDSRXUVROLGL¿HGDJDLQDQGRQO\WKHSK\VLFDOVWDWH DUUDQJHPHQWRISDUWLFOHV RIWKH
given substance changed without giving new substances. Such changes are called
physical changes.
In the instances from (ii) to (iv), the given substances changed forming new
substances. Such changes are known as chemical changes or chemical reactions.
2EVHUYDWLRQV VXFK DV EXUQLQJ ZLWK D ÀDPH HYROXWLRQ RI KHDW HIIHUYHVFHQFH
change in colour and precipitation can be given as evidences for the occurrence of
a chemical reaction.
To investigate physical and chemical changes further, let us study Table 16.1
Table 16.1
3K\VLFDOFKDQJHVDQGUHOHYDQW &KHPLFDOFKDQJHVDQGUHOHYDQW
observations observations
The arrangement of particles which The existing substances change.
form the substance changes. No new New substances are produced.
substances are produced.
Examples: Examples:
&UXVKLQJVWRQH (lumps powder) %XUQLQJ¿UHZRRG IRUPDWLRQRI
2.Melting of wax (solid liquid) ash, liberation of gases)
3.Vaporization of water (liquid gas) 2. Heating limestone (formation of
&RQGHQVDWLRQ RI ZDWHU vapour into quicklime, evolution of gas)
droplets (gas liquid) 3. Heating potassium permanganate
(liberation of oxygen)
4. Rusting of iron (formation of rust)
16.1 Chemical Changes
One of the following can happen during a chemical reaction.
Formation of new substances by the combination of two or more substances.
Turning one substances into two or more substances.
Reorganization of initial substances to form new substances.
The substances taking part in a chemical change are called the reactants. The new
substances produced by a chemical changes are known as the products.
During a chemical reaction, reactants turn into products.
Reactants products
87 For free distribution
, Chemistry Changes in Matter
To study the variety of chemical changes let us engage in activity 16.2.
Activity - 16.2
Requirements: magnesium ribbon, zinc granules, potassium permanganate,
barium chloride, sodium sulphate, boiling tubes, test tubes, a Bunsen burner, an
iron plate, a dry ekel , a box of matches, a pair of tongs.
i. +ROGDPDJQHVLXPULEERQLQWKH%XQVHQÀDPHZLWKWKHSDLURIWRQJV
ii. Heat crystals of potassium permanganate in a boiling tube. Insert a
glowing splint into the tube.
iii. Take some copper sulphate solution into a test tube and add a clean zinc
granule into it.
iv. Take a little barium chloride solution into a test tube and add a little
sodium sulphate solution into it.
&RPSOHWHWKH7DEOHXVLQJWKHDERYHFKHPLFDOFKDQJHV
Table 16.2
Reaction Nature of the Observation Nature of the
reactants products
i. Burning magnesium shiny, silvery Burns with a A white powder
in air white metal bright white
flame
ii.
iii.
iv.
$FFRUGLQJWRWKHQDWXUHRIWKHFKHPLFDOFKDQJHWKH\FDQEHFODVVL¿HGLQWRIRXU
types. They are as follows.
&KHPLFDOFRPELQDWLRQUHDFWLRQV
&KHPLFDOGHFRPSRVLWLRQUHDFWLRQV
Single displacement reactions
Double displacement (Double decomposition) reactions
Chemical Combination Reactions
&RQVLGHUWKH¿UVWUHDFWLRQRI$FWLYLW\,QLWPDJQHVLXPUHDFWVZLWKR[\JHQLQ
the air forming magnesium oxide.
magnesium + oxygen magnesium oxide
2Mg + O2 2MgO
Here, two elements have combined to form a new compound.
88 For free distribution
Chemistry
Changes in Matter
16
Objects made of iron rust when exposed to the air. Moth balls become smaller in
size when kept exposed to the air. Ice melts and turns into liquid water. We have
seen changes in matter like these. To study them further let us do the activity 16.1
given below.
Activity - 16.1
Requirements : A piece of magnesium (Mg) ribbon, about 50 ml of dilute sulfuric
acid (H2SO4), a few pellets of sodium hydroxide (NaOH), two metal spoons, a
moth ball (naphthalene), a box of matches, two 50 ml beakers, a Bunsen burner, a
thermometer
Do the activities (i), (ii), (iii) and (iv) and record the observations.
i). +HDWDPHWDOVSRRQVWURQJO\LQWKH%XQVHQÀDPHDQGWDNHLWDZD\IURP
WKHÀDPH3ODFHDPRWKEDOORQLWDQGREVHUYH&ORVHLWZLWKDQRWKHU
spoon quickly. After some time observe the inner side of the spoon.
ii). Hold a piece of cleaned magnesium ribbon with a pair of tongs and burn
it.
iii). Measure the initial temperature of a dilute sulfuric acid solution. Add a
few pellets of sodium hydroxide to this solution, stir and measure the
temperature again.
iv). 3XWDSLHFHRIPDJQHVLXPULEERQWRDEHDNHUFRQWDLQLQJGLOXWHVXOIXULF
acid.
See whether the observations you obtained through the above activities conform to
the following.
i). Moth ball melted and vaporized. A white powder deposited on the inner side
of the spoon.
ii). 0DJQHVLXPULEERQEXUQHGZLWKDZKLWHEULJKWÀDPHOHDYLQJDZKLWHSRZGHU
iii). Sodium hydroxide dissolved. The container became hot. The thermometer
reading rose.
iv). Magnesium ribbon dissolved liberating gas bubbles. The beaker was heated.
86 For free distribution
,Chemistry Changes in Matter
In case (i) above solid naphthalene melted and then turned into a vapour. On the cold
VXUIDFHRIWKHVSRRQWKHYDSRXUVROLGL¿HGIRUPLQJDWKLQVROLGOD\HURIQDSKWKDOHQH
When solid naphthalene melted, liquid naphthalene vaporized and naphthalene
YDSRXUVROLGL¿HGDJDLQDQGRQO\WKHSK\VLFDOVWDWH DUUDQJHPHQWRISDUWLFOHV RIWKH
given substance changed without giving new substances. Such changes are called
physical changes.
In the instances from (ii) to (iv), the given substances changed forming new
substances. Such changes are known as chemical changes or chemical reactions.
2EVHUYDWLRQV VXFK DV EXUQLQJ ZLWK D ÀDPH HYROXWLRQ RI KHDW HIIHUYHVFHQFH
change in colour and precipitation can be given as evidences for the occurrence of
a chemical reaction.
To investigate physical and chemical changes further, let us study Table 16.1
Table 16.1
3K\VLFDOFKDQJHVDQGUHOHYDQW &KHPLFDOFKDQJHVDQGUHOHYDQW
observations observations
The arrangement of particles which The existing substances change.
form the substance changes. No new New substances are produced.
substances are produced.
Examples: Examples:
&UXVKLQJVWRQH (lumps powder) %XUQLQJ¿UHZRRG IRUPDWLRQRI
2.Melting of wax (solid liquid) ash, liberation of gases)
3.Vaporization of water (liquid gas) 2. Heating limestone (formation of
&RQGHQVDWLRQ RI ZDWHU vapour into quicklime, evolution of gas)
droplets (gas liquid) 3. Heating potassium permanganate
(liberation of oxygen)
4. Rusting of iron (formation of rust)
16.1 Chemical Changes
One of the following can happen during a chemical reaction.
Formation of new substances by the combination of two or more substances.
Turning one substances into two or more substances.
Reorganization of initial substances to form new substances.
The substances taking part in a chemical change are called the reactants. The new
substances produced by a chemical changes are known as the products.
During a chemical reaction, reactants turn into products.
Reactants products
87 For free distribution
, Chemistry Changes in Matter
To study the variety of chemical changes let us engage in activity 16.2.
Activity - 16.2
Requirements: magnesium ribbon, zinc granules, potassium permanganate,
barium chloride, sodium sulphate, boiling tubes, test tubes, a Bunsen burner, an
iron plate, a dry ekel , a box of matches, a pair of tongs.
i. +ROGDPDJQHVLXPULEERQLQWKH%XQVHQÀDPHZLWKWKHSDLURIWRQJV
ii. Heat crystals of potassium permanganate in a boiling tube. Insert a
glowing splint into the tube.
iii. Take some copper sulphate solution into a test tube and add a clean zinc
granule into it.
iv. Take a little barium chloride solution into a test tube and add a little
sodium sulphate solution into it.
&RPSOHWHWKH7DEOHXVLQJWKHDERYHFKHPLFDOFKDQJHV
Table 16.2
Reaction Nature of the Observation Nature of the
reactants products
i. Burning magnesium shiny, silvery Burns with a A white powder
in air white metal bright white
flame
ii.
iii.
iv.
$FFRUGLQJWRWKHQDWXUHRIWKHFKHPLFDOFKDQJHWKH\FDQEHFODVVL¿HGLQWRIRXU
types. They are as follows.
&KHPLFDOFRPELQDWLRQUHDFWLRQV
&KHPLFDOGHFRPSRVLWLRQUHDFWLRQV
Single displacement reactions
Double displacement (Double decomposition) reactions
Chemical Combination Reactions
&RQVLGHUWKH¿UVWUHDFWLRQRI$FWLYLW\,QLWPDJQHVLXPUHDFWVZLWKR[\JHQLQ
the air forming magnesium oxide.
magnesium + oxygen magnesium oxide
2Mg + O2 2MgO
Here, two elements have combined to form a new compound.
88 For free distribution
