Gas Laws Questions and Answers - Chemistry Form 3 Topical Revision

Questions

1. A sample of unknown compound gas X is shown by analysis to contain Sulphur and Oxygen. The gas requires 28.3 seconds to diffuse through a small aperture into a vacuum. An identical number of oxygen molecules pass through the same aperture in 20 seconds. Determine the molecular mass of gas X (O= 16, S= 32)
2.  
   1. State Graham’s Law of diffusion
   2. Gas V takes 10 seconds to diffuse through a distance of one fifth of a meter. Another gas W takes the same time to diffuse through a distance of 10 cm. if the relative molecular mass of gas V is 16.0; calculate the molecular mass of W
3.  
   1. State Charles’ Law
   2. The volume of a sample of nitrogen gas at a temperature of 291K and 1.0 x 10⁵ Pascals was 3.5 x 10^-2 m³. Calculate the temperature at which the volume of the gas would be 2.8 x 10^-2 m³ at 1.0 x 10⁵ pascals.
4. 60 cm³ of oxygen gas diffused through a porous partition in 50 seconds. How long would it take 60 cm³ of sulphur (IV) oxide gas to diffuse through the same partition under the sane conditions? (S = 32.0, O = 16.0)
5.  
   1. State Graham’s law of diffusion
   2. 30cm³ of hydrogen chloride gas diffuses through a porous pot in 20 seconds. How long would it take 42cm³ of sulphur(IV) oxide gas to diffuse through the same pot under the same conditions (H =1 Cl = 35.5 S = 32 O =16)
6.  
   1. State Boyles law
   2. Sketch a graph that represents Charles’ law
   3. A gas occupied a volume of 250 cm³ at -23^º C and 1 atmosphere. Determine its volume at 127^º C when pressure is kept constant.
7. A factory produces Calcium Oxide from Calcium Carbonate as shown in the equation below:-
                 heat
   CaCO_{3 (s)}  →   CaO _(s) + CO_{2 (g)}
   What volume of Carbon (IV) Oxide would be produced from 1000kg of Calcium Carbonate at s.t.p (Ca = 40, C = 12, O = 16, Molar gas volume at s.t.p = 22.4dm³)
8. A fixed mass of gas occupies 200 cm³ at a temperature of 23oC and pressure of 740mmHg. Calculate the volume of the gas at -25oC and 780mmHg pressure
9. Gas K diffuses through a porous material at a rate of 12cm³ s^-1 where as S diffuses through the same material at a rate of 7.5cm³s^-1. Given that the molar mass of K is 16, calculate the molar mass of S
10. State Gay Lussac’s law
11.  
    1. What is the relationship between the rate of diffusion of a gas and its molecular mass?
    2. A sample of Carbon (IV) Oxide takes 200 seconds to diffuse across a porous plug.
       How long will it take the same amount of Carbon (II) Oxide to diffuse through the same plug?(C=12, O=16)
12. Below are structures of particles. Use it to answer questions that follow. In each case only electrons in the outermost energy level are shown
    key
    P = Proton
    N = Neutron
    X = Electron
    1. Identify the particle which is an anion
    2. Choose a pair of isotopes. Give a reason
13. The figure below shows two gases P and Q diffusing from two opposite ends 18 seconds after the experiment
    1. Which of the gases has a lighter density?
    2. Given that the molecular mass of gas Q is 17, calculate the molecular mass of P
14. Identify the particles that facilitate the electric conductivity of the following substances
    1. Sodium metal
    2. Sodium Chloride solution
    3. Molten Lead Bromide
15. Gas B takes 110 seconds to diffuse through a porous pot, how long will it take for the same amount of ammonia to diffuse under the same conditions of temperature and pressure? (RMM of B = 34 RMM of ammonia = 17)
16. A gas occupies 5dm³ at a temperature of -27^oC and 1 atmosphere pressure. Calculate the volume occupied by the gas at a pressure of 2 atmospheres and a temperature of 127^oC
17. A fixed mass of gas occupies 200 cm³ at a temperature of 23⁰c and a pressure of 740 mm Hg. Calculate the volume of the gas at -25⁰c and 790 mm Hg pressure.
18.  
    1. State the Graham’s law
    2. 100cm³ of Carbon (IV) oxide gas diffused through a porous partition in 30seconds. How long would it take 150cm3 of Nitrogen (IV) oxide to diffuse through the same partition under the same conditions? (C = 12.0, N = 14.0, O = 16.0)

Answers

1.  
   
2.  
   1. The rate of diffusion of a gas is inversely proportional to the square root of its density under the same conditions of temperature and pressure
      
      
      
      
      
      
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3.  
   1. The volume of a fixed mass of a gas is directly proportional to its absolute temperature at constant Pressure
   2.  
      
4.  
   
5.  
   1. The rate of diffusion of a fixed mass of a gas is inversely proportional to the square root of it density at constant temperature and pressure
      
      
      
      
      
      
      
      
      
   2.  
      
6.  
   1. Boyles’ law For a fixed mass of a gas, volume is inversely promotional to pressure at constant temperature
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8.  
   
   
   
9.  
   
10. When gases combine they do so in volume which bear a simple ratio to one another and to the product if gaseous under standard temperature and pressure
11.  
    1. Rate of diffusion is whereby proportional to molecular mass of a gas. √1
    2.  
       
12.  
    1. Y √1
    2. Z and W √1 have same atomic number but different mass number. √1
13.  
    1. Gas P
    2.  
       
14.  
    1. Delocalized electrons
    2. Mobile ions
    3. Mobile ions
15.  
    
16.  
    
17.  
    1.  
       
    2. 601 √1
18.  
    1. Grahams law states
       Under the same conditions of pressure and temperature, the rate of diffusion of a gas is inversely proportional to the square root of its density
    2.