Chemistry
Give reasons for the following:
Diamond & graphite are allotropic modifications of carbon.
It is dangerous to stand behind a running engine of a vehicle.
Both CO2 & SO2 turn lime water milky. Moist potassium permanganate paper, helps in distinguishing the two gases.
Carbon monoxide and not carbon dioxide is a highly poisonous gas.
Lime water finds application for testing both carbon dioxide & carbon monoxide gas individually.
Answer
Diamond & graphite are different in atomic arrangement in the crystal structure of the element. Hence they differ in physical properties but are forms of the same element carbon, and hence have similar chemical properties and are called allotropic forms of carbon.
It is dangerous to stand behind a running engine of a vehicle since in exhaust fumes carbon monoxide is present due to incomplete combustion of fuel in the engine.
SO2 turns potassium permanganate paper from purple to colourless whereas CO2 does not. Hence, the two gases can be distinguished.
Carbon monoxide has a very strong affinity for haemoglobin, binding to it about 200-250 times more strongly than oxygen to form a stable compound called carboxyhaemoglobin which prevents the haemoglobin from carrying oxygen efficiently. Carbon dioxide also combines with haemoglobin to form carbaminohaemoglobin but its affinity for haemoglobin is much weaker compared to oxygen and carbon monoxide. This makes carbon monoxide and not carbon dioxide a highly poisonous gas.
When carbon dioxide is bubbled into lime water, the lime water turns milky due to the formation of insoluble calcium carbonate.
Ca(OH)2 + CO2 ⟶ CaCO3 ↓ + H2O
When CO2 is bubbled in excess the milkiness disappears due to the formation of soluble calcium bicarbonate [Ca(HCO3)2]
CaCO3 + H2O + CO2 ⟶ Ca(HCO3)2
On the other hand lime water does not directly react with carbon monoxide.
CO + lime water ⟶ No milkiness.
However, on ignition, carbon monoxide burns with a pale blue flame forming carbon dioxide which reacts with lime water.
Related Questions
Name the following:
A crystalline allotrope of carbon built up from a hexagonal unit.
An allotrope of carbon used for the manufacture of coke.
An amorphous allotrope of carbon which floats on water.
An acid formed when carbon dioxide is dissolved in water under pressure.
The gaseous product obtained when carbon monoxide is passed over heated iron [III] oxide.
Select the correct answer from A, B, C, D & E for each statement given below:
A: Anthracite
B: Diamond
C: Carbogen
D: Urea
E: Lampblack
An allotrope of carbon used as a tip for deep boring, drills.
The type of coal with the highest carbon content.
An allotrope of carbon, obtained by burning kerosene oil in a limited supply of air.
A nitrogenous fertilizer obtained from carbon dioxide.
A compound which finds use for a victim of carbon monoxide poisoning.
Give a balanced equation for the following conversions: [In one or two steps]
Coke to water gas.
Calcium bicarbonate to calcium nitrate using a dilute acid
Lime water [soln. of calcium hydroxide] to calcium bicarbonate.
Carbon dioxide to carbon.
A metallic oxide to calcium carbonate.
Complete the statements by filling the blanks with the correct word from the bracket.
The crystal of …………… [diamond/graphite] is opaque to light and is a good conductor of heat.
A graphite-clay mixture baked at high temperature is used in making …………… [lubricants/refractory crucibles]
Adsorption capacity of wood charcoal is increased by passing …………… [carbon dioxide/steam] over wood charcoal, at high temperatures.
…………… [organic/inorganic] Chemistry is the Chemistry of carbon compounds mainly of 'Carbon', 'Hydrogen' & 'Oxygen'.
Sodium oxide combines with carbon dioxide to give …………… [sodium carbonate/sodium bicarbonate]