Page 182 - Chemistry ICSE Class IX

170 ICSE Chemistry – 9

ASSIGNMENT 1

Measurable parameters of gases, Boyle’s law (pressure-volume relationship)

ϭ͘ ĞĮŶĞ ƚŚĞ ƵŶŝƚ ƉĂƐĐĂů ;WĂͿ͘
Ϯ͘ tŚĂƚ ŝƐ ŵĞĂŶƚ ďLJ ŶŽƌŵĂů ƚĞŵƉĞƌĂƚƵƌĞ ĂŶĚ ƉƌĞƐƐƵƌĞ͍
ϯ͘ ,Žǁ ŝƐ ƚŚĞ ĂŵŽƵŶƚ ŽĨ Ă ŐĂƐ ƌĞůĂƚĞĚ ƚŽ ŝƚƐ ŵĂƐƐ͍
ϰ͘ EĂŵĞ ƚŚĞ ƚǁŽ ƚĞŵƉĞƌĂƚƵƌĞ ƐĐĂůĞƐ ǁŚŝĐŚ ŚĂǀĞ ƚŚĞ ƐĂŵĞ ĚĞŐƌĞĞ ƐŝnjĞ͘
ϱ͘ ^ƚĂƚĞ ƚŚĞ ŽLJůĞ͛Ɛ ůĂǁ͘
ϲ͘ ƌĂǁ Ă ƚLJƉŝĐĂů ƉƌĞƐƐƵƌĞͲǀŽůƵŵĞ ŐƌĂƉŚ ĨŽƌ Ă ŐĂƐ͘
ϳ͘ tŚLJ ĚŽĞƐ ƚŚĞ ƐŝnjĞ ŽĨ ĂŶ Ăŝƌ ďĂůůŽŽŶ ďĞĐŽŵĞ ůĂƌŐĞƌ ĂƐ ŝƚ ĂƐĐĞŶĚƐ ŝŶƚŽ ŚŝŐŚĞƌ ĂůƟƚƵĚĞƐ͍
ϴ͘ ϴϴ ŵ> ŽĨ ŶŝƚƌŽŐĞŶ ŝƐ Ăƚ Ă ƉƌĞƐƐƵƌĞ ŽĨ ϳϳϬ ŵŵ ,Ő͘ dŚĞ ƉƌĞƐƐƵƌĞ ŝƐ ƚŚĞŶ ƌĂŝƐĞĚ ƚŽ ϴϴϬ ŵŵ ,Ő͘ &ŝŶĚ ďLJ ŚŽǁ ŵƵĐŚ ƚŚĞ
ǀŽůƵŵĞ ǁŽƵůĚ ĚŝŵŝŶŝƐŚ͕ ŝĨ ƚŚĞ ƚĞŵƉĞƌĂƚƵƌĞ ƌĞŵĂŝŶƐ ĐŽŶƐƚĂŶƚ͘ [Ans. ϭϭ ŵ>΁
ϵ͘ ŐĂƐ ŽĐĐƵƉŝĞƐ ϯ > Ăƚ Ϭ͘ϱ Ăƚŵ ƉƌĞƐƐƵƌĞ͘ tŚĂƚ ǀŽůƵŵĞ ǁŝůů ŝƚ ŽĐĐƵƉLJ Ăƚ Ϭ͘Ϭϱ Ăƚŵ ƉƌĞƐƐƵƌĞ ŝĨ ƚŚĞ ƚĞŵƉĞƌĂƚƵƌĞ ƌĞŵĂŝŶƐ
ĐŽŶƐƚĂŶƚ͘ [Ans. ϯϬ >΁
ϭϬ͘ ƐĂŵƉůĞ ŽĨ ĐĂƌďŽŶ ĚŝŽdžŝĚĞ ŽĐĐƵƉŝĞƐ ϴϬ ŵ> Ăƚ ϳϰϬ ŵŵ ,Ő ƉƌĞƐƐƵƌĞ͘ &ŝŶĚ ŝƚƐ ǀŽůƵŵĞ ƵŶĚĞƌ ŶŽƌŵĂů ƉƌĞƐƐƵƌĞ͕ ŝĨ ƚĞŵƉĞƌĂƚƵƌĞ
ƌĞŵĂŝŶƐ ĐŽŶƐƚĂŶƚ͘ [Ans. ϳϳ͘ϵ ŵ>΁

Charles’ Law (Volume-Temperature Relationship)

What is the Charles’ law

Charles (1787) and later Gay-Lussac (1808) observed that at any
constant pressure, the volume of a certain amount of gas varies
linearly with temperature on the Celsius scale.
A typical variation of volume with temperature is shown in
Fig. 7.5.
Experimentally, Charles found that the slope of the volume-
pressure (V–P) plots is always found to be equal to V /273 (more
0
precise value was later found to be V /273.15).
0
This observation was generalised by Charles in the form of the
Fig. 7.5 Variation of volume of certain amount statement: The volume of a certain amount of a gas increases or
of gas with temperature under constant 1
pressure conditions decreases by 273 part of its volume at 0°C for each degree rise or fall
in temperature.
This statement is called the Charles’ law.
Mathematically, the Charles’ law may be written as,
dŚĞ ǀŽůƵŵĞͲƚĞŵƉĞƌĂƚƵƌĞ ƉůŽƚ ƵŶĚĞƌ
ĐŽŶƐƚĂŶƚ ƉƌĞƐƐƵƌĞ ĐŽŶĚŝƟŽŶƐ ŝƐ ĐĂůůĞĚ V = V + V 0 t°C (7.6)
ĂŶ isobar͘ 0 273.15
where, V is the volume of gas at t°C.
V is the volume of gas at 0°C.
0
Eq. 7.6 may be written as
⎛ t (C)° ⎞
V = V 0 ⎜ ⎝ 1+ 273.15 ⎠ ⎟

⎛ 273.15 t+°
( C) ⎞
or V = V 0 ⎜ ⎝ 273.15 ⎟ ⎠
V
or V = 0 × T
273.15