Advertisements
Advertisements
प्रश्न
Washing soda has formula Na2CO3.10H2O. What mass of anhydrous sodium carbonate is left when all the water of crystallization is expelled by heating 57.2 g of washing soda?
उत्तर
\[\ce{Na2CO3.10H2O ->[Heat] Na2CO3 + 10H2O}\]
Molecular weight of Na2CO3.10H2O = 23 × 2 + 12 + 16 × 3 + 10[1 × 2 + 16]
= 46 + 12 + 48 + 10[18]
= 106 + 180
= 286
Molecular weight of Na2CO3 = 106
∵ 286 g Na2CO3.10H2O left 106 g Na2CO3
∴ 57.2 g Na2CO3.10H2O left Na2CO3 = `(57.2 xx 106)/286`
= 21.2 g Na2CO3
The mass of anhydrous sodium carbonate is 21.2 g.
APPEARS IN
संबंधित प्रश्न
Differentiate between 2H and H2
560ml of carbon monoxide is mixed with 500ml of oxygen and ignited. The chemicaI equation for the reaction is as folIows:
2CO + O2 → 2CO2
Calculate the volume of oxygen used and carbon dioxide formed in the above reaction.
O2 is evolved by heating KCIO3 using MnO2 as a catalyst.
\[\ce{2KCI3 ->[MnO2] 2KCl + 3O2}\]
- Calculate the mass of KClO3 required to produce 6.72 litres of O2 at STP. [atomic masses of K = 39, Cl = 35.5, O = 16].
- Calculate the number of moles of oxygen present in the above volume and also the number of molecules.
- Calculate the volume occupied by 0.01 mole of CO2 at STP.
The ratio between the number of molecules in 2g of hydrogen and 32 g of oxygen is
[Given that H=1,O=16]
Find the mass of KNO3 required to produce 126 kg of nitric acid. Find whether a larger or smaller mass of NaNO3 is required for the same purpose.
\[\ce{KNO3 + H2SO4 -> KHSO4 + HNO3}\]
\[\ce{NaNO3 + H2SO4 -> NaHSO4 + HNO3}\]
Pure calcium carbonate and dilute hydrochloric acid are reacted and 2 litres of carbon dioxide were collected at 27oC and normal pressure.
\[\ce{CaCO3 + 2HCl -> CaCl2 + H2O + CO2}\]
Calculate the mass of salt required.
Solid ammonium dichromate decomposes as:
\[\ce{(NH4)2Cr2O7 -> N2 + Cr2O3 + 4H2O}\]
If 63 g of ammonium dichromate decomposes. Calculate what will be the loss of mass.
Given that the relative molecular mass of copper oxide is 80, what volume of ammonia (measured at STP) is required to completely reduce 120g of copper oxide? The equation for the reaction is:
\[\ce{3CuO + 2NH3 → 3Cu + 3H2O + N2}\]
66g of ammonium sulphate is produced by the action of ammonia on sulphuric acid. Write a balanced equation and calculate the volume of the gas used at STP.
Concentrated nitric acid oxidizes phosphorus to phosphoric acid according to the following equation:
\[\ce{P + 5HNO3 -> H3PO4 + 5NO2 + H2O}\]
If 6.2 g of phosphorus was used in the reaction, calculate the volume of steam produced at the same time if measured at 760 mm Hg pressure and 273°C.
