Page 130 - Chemistry ICSE Class X

116 ICSE Chemistry – 10

W
23
= × 6.02 × 10 molecule
M
where, W is the mass of the substance.
M is the molar mass (in g/mol) of the substance.

How many moles are there in a certain volume of a
gaseous substance
To calculate the number of moles of a gaseous substance in a certain
volume, we use the relationship that one mole of any gaseous substance
under NTP conditions occupies 22.4 L, or 22400 mL of volume. Let,
Volume of the gaseous substance at NTP = V L
Molar volume under NTP = 22.4 L/mol
So,
Volume (in litres) of the substance at NTP
No. of moles of the substance in V litre =
22.4 litre/mol
V litre V
= = mol
22.4 litre/mol 22.4
V
23
No. of molecules of the substance in V litre = mol × 6.02 × 10 molecules/mol
22.4
V
23
= × 6.02 × 10 molecules
22.4

ASSIGNMENT 1

The mole concept

ϭ͘ tŚĂƚ ŝƐ ƚŚĞ ŵŽůĞ ĐŽŶĐĞƉƚ͍
+
–
Ϯ͘ džƉƌĞƐƐ ŽŶĞ ŵŽůĞ ŽĨ ƐŽĚŝƵŵ ĐŚůŽƌŝĚĞ ;EĂ ů Ϳ ŝŶ ĂƐ ŵĂŶLJ ǁĂLJƐ ĂƐ ƉŽƐƐŝďůĞ͘
ϯ͘ tŚĂƚ ŝƐ ƚŚĞ ĚŝīĞƌĞŶĐĞ ďĞƚǁĞĞŶ ŵŽůĞĐƵůĂƌ ŵĂƐƐ ĂŶĚ ƚŚĞ ŵŽůĂƌ ŵĂƐƐ ŽĨ Ă ƐƵďƐƚĂŶĐĞ͍
ϰ͘ ĂůĐƵůĂƚĞ ƚŚĞ ŵŽůĞĐƵůĂƌ ŵĂƐƐ ŽĨ ƚŚĞ ĨŽůůŽǁŝŶŐ ĐŽŵƉŽƵŶĚƐ͗
;ĂͿ H K,പപപ;ďͿ W ů പപപ;ĐͿ , O പപപ;ĚͿ ,EK [Ans. ;ĂͿ ϰϲ Ƶ ;ďͿ ϮϬϴ͘ϱ Ƶ ;ĐͿ ϯϰ Ƶ ;ĚͿ ϲϯ Ƶ]
Ϯ 5
5
Ϯ Ϯ
ϯ
ϱ͘ ĞĮŶĞ ƚŚĞ ƚĞƌŵ ŵŽůĞ ďŽƚŚ ŝŶ ƚĞƌŵƐ ŽĨ ;ĂͿ ŶƵŵďĞƌ ĂŶĚ ;ďͿ ŵĂƐƐ͘
ϲ͘ tŚĂƚ ŝƐ ƚŚĞ ŶƵŵďĞƌ ŽĨ ǁĂƚĞƌ ŵŽůĞĐƵůĞƐ ĐŽŶƚĂŝŶĞĚ ŝŶ Ă ĚƌŽƉ ŽĨ ǁĂƚĞƌ ǁĞŝŐŚŝŶŐ Ϭ͘Ϭϲ Ő͍
ϳ͘ ^ƵƉƉŽƐĞ ƚŚĞ ĐĂƌďŽŶͲϭϮ ŝƐŽƚŽƉĞ ǁĂƐ ĂƐƐŝŐŶĞĚ ĂŶ ĂƚŽŵŝĐ ŵĂƐƐ ŽĨ ϭϬϬ͘ϬϬϬ ŝŶƐƚĞĂĚ ŽĨ ϭϮ͘ϬϬϬ ĂƚŽŵŝĐ ŵĂƐƐ ƵŶŝƚƐ͘ tŚĂƚ ǁŽƵůĚ
ďĞ ƚŚĞ ĂƚŽŵŝĐ ŵĂƐƐĞƐ ŽĨ ,͕ K ĂŶĚ E͍ tŚĂƚ ǁŽƵůĚ ďĞ ƚŚĞ ŶƵŵďĞƌ ŽĨ ƉĂƌƟĐůĞƐ ŝŶ Ă ŵŽůĞ ŽĨ ĂŶLJ ƐƵďƐƚĂŶĐĞ͍
Ϯϰ
[Ans. ϴ͘ϯϯ͕ ϭϯϯ͘ϯϯ͕ ϭϭϲ͘ϲϳ͖ ϱ͘ϬϮ п ϭϬ ]
Ϯϯ
ϴ͘ tŚĂƚ ŝƐ ƚŚĞ ŵĂƐƐ ŽĨ ϲ п ϭϬ ĂƚŽŵƐ ŽĨ ĐŽƉƉĞƌ͍ [Ans. ϲϯ͘ϱ Ő]
ϵ͘ ,Žǁ ǁŽƵůĚ LJŽƵ ĞdžƉůĂŝŶ ƚŽ Ă ŶŽŶͲĐŚĞŵŝƐƚ ƚŚĞ ĨĂĐƚ ƚŚĂƚ ĨŽƌ ŵĂŶLJ ŽĨ ŚŝƐ ĐĂůĐƵůĂƟŽŶƐ͕ ƚŚĞ ĐŚĞŵŝƐƚ ĮŶĚƐ ŝƚ ĐŽŶǀĞŶŝĞŶƚ ƚŽ
ĞŵƉůŽLJ Ă ƵŶŝƚ͕ ƚŚĞ ŵŽůĞ͕ ǁŚŝĐŚ ǀĂƌŝĞƐ ĨƌŽŵ ŽŶĞ ƐƵďƐƚĂŶĐĞ ƚŽ ĂŶŽƚŚĞƌ͍
ϭϬ͘ ĂůĐƵůĂƚĞ ƚŚĞ ǀŽůƵŵĞ ŽĨ ϰ Ő ŽĨ ŽdžLJŐĞŶ ƵŶĚĞƌ EdW ĐŽŶĚŝƟŽŶƐ͘ [Ans. Ϯ͘ϴ >]
ϮϮ
ϭϭ͘ ĂůĐƵůĂƚĞ ƚŚĞ ŶƵŵďĞƌ ŽĨ ŵŽůĞĐƵůĞƐ ŽĨ ĐĂƌďŽŶ ĚŝŽdžŝĚĞ ŝŶ ϰ͘ϰ Ő ŽĨ ĐĂƌďŽŶ ĚŝŽdžŝĚĞ ŐĂƐ͘ [Ans. ϲ͘ϬϮ п ϭϬ ]

Gay-Lussac’s Law of Combining Volumes

Gay-Lussac (1805) put forward an interesting volume-volume relationship
between the volumes of the reactants and products, if gaseous. This law is
known as the Gay-Lussac’s law of combining volumes. According to this
law,