Chem Notes 2nd Year Chap 5

                                 Important Questions

 

Q1 Why flourine act as a strong oxidizing agent ?

Ans: The oxidizing power of halogen depends upon the dissocation energy electron effinity hydration energy of the atoms. Oxidizing power of flourine is higher because of its dissocation energy higher electron affinity and higher hydration energy. Due to these properties the hydration act as strong oxidizing agent.

Q2 What are the disporportionation ractions ?

Ans: A reaction in which same species udergo the oxidation the reduction process is called the disporpotionation reaction of self-oxidation reduction process. As chlorine reacts with NaOH  is cold state producing  NaCl  and NaClO. The oxidation state of Cl changes from zero to -1 and zero to +1 respectively therefore it is disporportination reaction.

 2NaOH+Cl2--------> NaCl+NaClO+H2O

Q3 Give important uses of helium and argon.?

Ans:Helium is used in treatment of asthma, filling the weather balloons producing low temperature preservation of food crating inert atmosphere and welding. It also used in signal lights and atomic reactions.
            Argon are used in filling electrical bulb in the Geiger Contour producing inert atmosphere filling the tube light and mixing with Neon in the Neon signs.

Q4 : Why fluorine act chlorine act as decolourizing agent ?

Ans: They can oxidize the dyes to colourless substances. Litmus ans Universal indicators can be decolourized. Chlorine is used in the bleaching powder which bleaches the substances due their Oxidizing capabilities of Chlorine.

Q5 What is effect is the effect of high voltage on noble Gases ?

Ans: When the noble gases are maintainted at low pressure in the discharge tube and electric current  is passed trough them spectra of different colours are produced. These spectra are utilized in advertising lemp.

Q6 : Name two gases one of which is used for earthquake prediction and the other are used in bacterial lamps.

Ans: Xenon is used in the bacterial lamps
          Radon is used for earthquake.

Q7 Halogens are strong oxidizing agent ?

Ans: Halogen have the tendencies to loss the electrons and so they oxidize the other species. Their oxidizing power depend upon the dissociation energy electron affinity and hydration energy of the atoms. Oxidizing power of  fluorine is higher because its low dissociation energy higher electron affinity and high hydration energy. Due to these properties the fluorine act as strong oxidizing agent. Anyhow their oxidizing capabilities decreases down the group. Fluorine strong oxidizing agent and Iodine weakest.

Q8 F2 is gas while I2 is solid at room temperature why ?

Ans: Due to the smaller size of fluorine exit in the  gaseous state  where as the iodine having larger size and high polarizability it exist in the solid state due to stronger London dispertion forces.

Q9 What is the formula of bleaching powder ? Write chemical equation fir its preparation.

Ans: Chemical formula if bleaching powder is produced by the Odling. It can be writthen as  Ca(OCl)Cl.
                    It can be prepared by the reaction of slaked lime with chlorine as give below
                                      Ca(OH)2+Cl2---------->Ca(OCl)Cl+H2O

Q10 What are the factor affecting the oxidizing power of haloogen depends upon ?

Ans: Following are the factors affecting the oxidizing power of halogen.

            i  Energy of dissocication
           ii  Electron effinity of atoms
           iii   Hydration energies of ions
           iv   Heats of  vapourization

Q11 What are the changes associated with the increases is oxidation  state of  halogen in oxy acids.

Ans: The increase in oxidation state of halogen from +1 to +7 accompained.
                  i   An increase in thermal stability
                 ii   Decrease in oxidizing power of acids.
                 iii  Increase in acidic strength of acid

Q12  Which halogen is used as antiseptic and which one has violet fumes ?

Ans: Iodine  is uses an antiseptic and Iodine.

Q13  Why boiling point of HF is much higher than those of other hydrogen halides ?

Ans:  Due to presence of  Hydrogen bonding in case of HF its boiling point is much higher than other hydrogen halides.

Q14 Give two application of Iodine

Ans:  Ionic fluorides possess higher lattice energy & soluble in water than halide of other halogens.
              Fluorine can only -1 show oxidation state while other can show the higher oxidation state.
              Fluorine is the only element which reacts with the noble gases.

Q15  Which Halogen is used in water treatment to kill bacteria ?

Ans: Chloride is used in the water treatment. Chlorine is an oxidizing agent and releases atomic oxygen by reacting with water and this atomic oxygen is very reactive and kills the bacteria present in water.

Q16 What is Teflon ? Give its uses

Ans: The polymerized tetrafluoro ethylene compouds ( __CF2__CF2___)  are called teflon. It is used in the construction of chemical plants. It is used as insulating material in cables. It is used in making the corrosion free parts of machine. It is used in making the nonstick cooking pans.

Q17 What are Ferons ? Give their Uses.

Ans: These are low molecular mass ChlororfluroCarbons obtained from CCl4 are called the Ferons. It is the mixture of CCl2F2 and CClF3. They are used as solvents,lubricants,insulators,refrigerantsand in aerosol propellants.