Chemistry
The volume of gases A, B, C and D are in the ratio, 1 : 2 : 2 : 4 under the same conditions of temperature and pressure .
(i) Which sample of gas contains the maximum number of molecules?
(ii) If the temperature and pressure of gas A are kept constant, then what will happen to the volume of A when the number of molecules is doubled?
(iii) If this ratio of gas volume refers to the reactants and products of a reaction, which gas law is being observed?
(iv) If the volume of A is actually 5.6 dm3 at S.T.P., calculate the number of molecules in the actual Volume of D at S.T.P. (Avogadro's number is 6 × 1023).
(v) Using your answer from (iv), state the mass of D if the gas is dinitrogen oxide (N2O)
Answer
(i) Volume is directly proportional to the number of molecules, hence gas D will have maximum no. of molecules as its volume is maximum.
(ii) If number of molecules of gas A is doubled, the volume will also be doubled i.e. 2V.
(iii) Gay Lussac's Law is observed.
(iv) 1 mole contains 6 x 1023 number of molecules and occupies 22.4 lit. vol.
Given, volume of 'A' is 5.6 dm3 at s.t.p.
∴ vol. of D will be 4 × 5.6 = 22.4 lit.
No. of molecules in 22.4 lit. of D = 6 x 1023 (Avogadro no.)
(v) As D is 1 mole hence, mass of 1 mole of D (N2O) = 2(14) + 16 = 28 + 16 = 44 g
Hence, mass of N2O = 44 g
Related Questions
When heated, potassium permanganate decomposes according to the following equation:
2KMnO4 ⟶ 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)
(a) A flask contains 3.2 g of sulphur dioxide. Calculate the following:
(i) The moles of sulphur dioxide present in the flask.
(ii) The number of molecules of sulphur dioxide present in the flask.
(iii) The volume occupied by 3.2 g of sulphur dioxide at S.T.P.
(b) An Experiment showed that in a lead chloride solution, 6.21 g of lead is combined with 4.26 g of chlorine. What is the empirical formula of this chlorine? (Pb = 207; Cl = 35.5)
The equations given below relate to the manufacture of sodium carbonate [Mol. wt. of Na2CO3 = 106]
(i) NaCl + NH3 + CO2 + H2O ⟶ NaHCO3 + NH4Cl
(ii) 2NaHCO3 ⟶ Na2CO3 + H2O + CO2
Equations (1) and (2) are based on the production of 21.2 g. of sodium carbonate.
(a) What mass of sodium hydrogen carbonate must be heated to give 21.2 g. of sodium carbonate
(b) To produce the mass of sodium hydrogen carbonate calculated in (a), what volume of carbon dioxide, measured at s.t.p., would be required.
A sample of ammonium nitrate when heated yields 8.96 litres of steam (measured at STP)
NH4NO3 ⟶ N2O + 2H2O
(i) What volume of di nitrogen oxide is produced at the same time as 8.96 litres of steam.
(ii) What mass of ammonium nitrate should be heated to produce 8.96 litres of steam [Relative molecular mass of NH4NO3 is 80]
(iii) Determine the percentage of oxygen in ammonium nitrate [O = 16]