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प्रश्न
What is meant by the ‘molar mass’ of a substance ? State the unit in which molar mass is usually expressed.
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उत्तर
Molar mass of a substance (molecular compound) is the mass in grams, numerically equivalent to the sum of atomic masses of individual atoms in the molecular formula of that substance.
Molar mass of a substance is usually expressed as grams/mole.
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संबंधित प्रश्न
Calculate the molecular mass of O2.
Calculate the molecular mass of Cl2.
Calculate the molecular mass of hydrogen bromide (HBr). (Atomic masses : H = 1 u ; Br = 80 u)
Calculate the molecular masses of the following :
Carbon dioxide, CO2
(Atomic masses : H = 1 u ; O = 16 u ; Cl = 35.5 u ; N = 14 u ; C = 12 u)
Calculate the molecular masses of the following compounds :
Ethyne, C2H2
(Atomic masses : C = 12 u ; H = 1 u)
Define gram molecular mass of a substance. How much is the gram molecular mass of oxygen ?
From the equation:
\[\ce{C + 2H2SO4 -> CO2 + 2H2O + 2SO2}\]
Calculate:
- the mass of carbon oxidized by 49 g of sulphuric acid (C = 12, relative molecular mass of sulphuric acid = 98)
- the volume of sulphur dioxide measured at STP, liberated at the same time.
(Volume occupied by 1 mole of a gas at STP is 22.4 dm3).
Calculate the molecular mass of the following:
Ammonium chloroplatinate (NH4)2 PtCl6
[At mass: C = 12, H = 1, O = 16, Cl = 35.5, N = 14, Cu = 63.5, S = 32, K = 39, Pt = 195, Ca = 40, P = 31, Mg = 24]
Calcium carbonate is decomposed on heating in the following reaction
CaCO3 → CaO + CO2
Calculate the gram molecular mass of calcium carbonate involved in this reaction.
Write the formulae for the following and calculate the molecular mass for each one of them.
- Caustic potash
- Baking powder
- Limestone
- Caustic soda
- Ethanol
- Common salt
