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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
Convert into mole.
12 g of oxygen gas
A gas cylinder can hold 1 kg of hydrogen at room temperature and pressure
1) Find the number of moles of hydrogen present.
2) What weight of CO2 can the cylinder hold under similar conditions of temperature and pressure? (H = 1, C = 12, O = 16)
3) If the number of molecules of hydrogen in the cylinder is X, calculate the number of CO2 molecules in the cylinder under the same conditions of temperature and pressure.
4) State the law that helped you to arrive at the above result.
What weight of each element is present in 1.5 moles of sodium sulphite, Na2SO3 ?
(Atomic masses : Na = 23 u ; S = 32 u ; O = 16 u)
The ratio of moles of atoms in 12 g of magnesium and 16 g of sulphur will be :
What do you understand by the term mole? How many elementary units are in one mole of a substance?
Calculate the number of molecules in 12.8g of sulphur dioxide gas. Take Avogadro's number as 6 x 1023.
[S = 32, 0 = 16 ]
Calculate the weight of one molecule of oxygen.
[Avogadro’s number = 6 × 1023, O = 16 ]
Complete the following calculations. Show working for complete credit :
Calculate the mass of calcium that will contain the same number of atoms as are present in 3.2 gm of Sulphur. [Atomic masses : S = 32, Ca = 40]
Define or explain the term:
Relative atomic mass
Find the number of molecules in 73 g of HCl.
Find the number of moles in 10 g of CaCO3.
Calculate the number of molecules in one Kg of calcium chloride.
How many grams of Al are present in 0.2 mole of it?
How many grams of H2O are present in 0.2 mole of it?
Cost of Sugar (C12H22 O11) is Rs 40 per kg; calculate its cost per mole.
Calculate the number of gram atoms in 4.6 gram of sodium.
How many grams are there in the following?
4 moles of the phosphorous molecule, P4
Calculate the number of moles of magnesium present in a magnesium ribbon weighing 12 g. Molar atomic mass of magnesium is 24g mol–1.
If 0.2 mol of the following substance is required how many grams of that substance should be taken?
magnesium oxide
If 0.2 mol of the following substance is required how many grams of that substance should be taken?
Calcium carbonate
