Advertisements
Advertisements
प्रश्न
Complete the following calculations. Show working for complete credit :
If the empirical formula of a compound is CH and it has a vapour density of 13, find the molecular formula of the compound.
Advertisements
उत्तर
For acetylene , molecular mass = 2 X V.D. = 2 x 13 = 26g
The empirical mass = 12 (c) + 1(H) = 13g
n = `"Molecular formula mass"/"Empirical formula weight"`
= `26/13` = 2
Molecular formula of acetylene = 2 x Empirical formula =C2H2
Similarly, for benzene molecular mass = 2 X V.D = 2 x 39 = 78
n = 78/13 = 6
So, the molecular formula = C6H6.
APPEARS IN
संबंधित प्रश्न
Aluminum carbide reacts with water according to the following equation:
\[\ce{Al4C3 + 12H2O -> 4Al(OH)3 + 3CH4}\]
- What mass of aluminum hydroxide is formed from 12g of aluminum carbide?
- What volume of methane at s.t.p. is obtained from 12g of aluminum carbide?
Samples of the gases O2, N2, CO2 and CO under the same conditions of temperature and pressure contain the same number of molecules represented by X. The molecules of Oxygen, occupy V litres and have a mass of 8 g. Under the same conditions of temperature and pressure :
What is the mass of CO2 in g?
Calculate the percentage of platinum in ammonium chloroplatinate (NH4)2PtCl6.
[N = 14, H = 1, Pt = 195, Cl =35.5]
(Give your answer correct to the nearest whole number)
A compound 'X' consists of 4.8% of C and 95.2% of Br by mass.
Name the type of chemical reaction by which X can be prepared from ethane.
4.5 moles of calcium carbonate are reacted with dilute hydrochloric acid.
- Write the equation for the reaction.
- What is the mass of 4.5 moles of calcium carbonate? (Relative molecular mass of calcium carbonate is 100).
- What is the volume of carbon dioxide liberated at STP?
- What mass of calcium chloride is formed? (Relative molecular mass of calcium chloride is 111).
- How many moles of HCl are used in this reaction?
Find the weight of 0.5 mole of O2.
Find the weight of 0.2 mole of H2 gas.
Calculate the number of atoms of each kind in 5.3 grams of sodium carbonate.
A gas cylinder can hold 1 kg of hydrogen at room temperature and pressure. What mass of carbon dioxide can it hold under similar conditions of temperature and pressure?
When heated, potassium permanganate decomposes according to the following equation :
\[\ce{2KMnO4 -> \underset{\text{solid residue}}{K2MnO4 + MnO2} + O2}\]
(a) Some potassium permanganate was heated in the test tube. After collecting one litre of oxygen at room temperature, it was found that the test tube had undergone a loss in mass of 1.32 g. If one litre of hydrogen under the same conditions of temperature and pressure has a mass of 0.0825 g, calculate the relative molecular mass of oxygen.
(b) Given that the molecular mass of potassium permanganate is 158. What volume of oxygen (measured at room temperature) would be obtained by the complete decomposition of 15.8 g of potassium permanganate? (Molar volume at room temperature is 24 litres)
