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प्रश्न
Explain with examples what is meant by a 'mole' of a substance.
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उत्तर
A mole is the quantity of a substance whose mass in grams is equal in magnitude to the molecular mass of that substance in Daltons. Thus, the molecular mass of oxygen is 32 u, and therefore 32g oxygen is 1 mole of oxygen. The molecular mass of water is 18u. Therefore, 18g of water makes 1 mole of water.
1 mole of a compound is the mass of that substance in grams equal in magnitude to its molecular mass. The SI unit is mol.
Number of moles of substances (n) = `"Mass of substance in grams"/"Molecular mass of substance"`
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संबंधित प्रश्न
Calculate the molar mass of the following substance:
Ethyne, C2H2
What is the mass of 4 moles of aluminium atoms (Atomic mass of aluminium = 27)?
Calculate the number of moles in 12g of oxygen gas.
Fill in the following blanks :
64 g of oxygen gas contains ................ moles of oxygen atoms.
How many moles are represented by 100 g of glucose, C6H12O6 ? (C = 12 u, H = 1 u, O = 16 u)
Show by means of calculations that 5 moles of CO2 and 5 moles of H2O do not have the same mass. How much is the difference in their masses ?
Calculate the mole ratio of 240 g of calcium and 240 g of magnesium. (Ca = 40 u ; Mg = 24 u)
Explain the term:
Mole
Fill in the blank
One gram atom of an element contains ______ atoms.
A sample of ammonium nitrate when heated yields 8.96 litres of steam (measured at STP)
NH4NO3 → N2O + 2H2O
What mass of ammonium nitrate should be heated to produce 8.96L of steam?
Which of the following would weight the least?
[Atomic masses : Ag = 108, N - 14, O = 16,C = 12]
Consider the following reaction and based on the reaction answer the questions that follow :
\[\ce{(NH4)2Cr2O7 ->[heat] N2(g) + 4H2O(g) + Cr2O3}\]
Calculate :
(i) The quantity in moles of (NH4)2Cr2O7 if 63 gm of (NH4)2Cr2O7 is heated.
(ii) The quantity in moles of nitrogen formed.
(iii) The volume in litres or dm3 of N2evolved at STP.
(iv) The mass in grams of Cr2O3 formed at the same time
[Atomic masses : H = 1, Cr=52, N=14]
Define or explain the term:
Relative atomic mass
How many grams of Al are present in 0.2 mole of it?
Calculate the number of moles of methane in 0.80 g of methane.
Calculate the mass of 0.1 mole of the following:
CaCl2
(Ca = 40, Na=23, Mg =24, S=32, C = 12, Cl = 35.5, O=16, H=1)
The molecular formula for elemental sulphur is S8.In a sample of 5.12 g of sulphur:
How many molecules and atoms are present?
Fill in the missing data in the Table
| Species Property | H2O | CO2 | Na atom | MgCl2 |
| No. of moles | 2 | - | - | 0.5 |
| No. of particles | - | 3.011×1023 | - | - |
| Mass | 36g | - | 115 g | - |
The number of atoms present in 0.1 mole of P4 (at. mass = 31) is ______.
