Account for the following:
(i) dihydrogen gas is not preferred in balloons.
(ii) Cone. H2S04 cannot be used for drying H2.
(i) Dihydrogen is the lighest gas but due to its highly combustible nature it is not preferred in balloons.
(ii) Cone. H2S04 on absorbing H2O forms moist H2 produces so much heat that hydrogen catches fires.
Dihydrogen reacts with dioxygen (02) to form water. Write the name and formula of the product when the isotope of hydrogen which has one proton and one neutron in its nucleus is treated with oxygen. Will the reactivity of both the isotopes be the same towards oxygen? Justify your answer.
Consider the reaction of water with F2 and suggest, in terms of oxidation and reduction, which species are oxidised/reduced ?
Why does H+ ion always get associated with other atoms or molecules?
(a) Ionisation enthalpy of hydrogen resembles that of alkali metals.
(b) Its reactivity is similar to halogens.
(c) It resembles both alkali metals and halogens.
(d) Loss of an electron from hydrogen atom results in a nucleus of very small size as compared to other atoms or ions. Due to small size it can not exist freely.
Do you expect different products in solution when aluminium (III) chloride and potassium chloride treated separately with (i) normal water (ii) acidified water (iii) alkaline water? Write equation wherever necessary.
Which of the following reactions increases production of dihydrogen from synthesis gas?
(a) How is dihydrogen prepared from water by using a reducing agent?
(b) Give the industrial use of dihydrogen which depends upon heat liberated when it bums.
Hydrogen resembles halogens in many respects for which several factors are responsible. Of the following factors which one is most important in this respect?
(a) Its tendency to lose an electron to form a cation.
(b) Its tendency to gain a single electron in its valence shell to attain stable electronic configuration.
(c) Its low negative electron gain enthalpy value.
(d) Its small size.
Hydrogen peroxide is obtained by‘the electrolysis of _______.
(a) water
(b) sulphuric acid
(c) hydrochloric acid
(d) fused sodium peroxide
Among NH3 H2O and HE, which would you expect to have highest magnitude of hydrogen bonding and why?
Explain the following:
(i) Temporary hardness can remove by boiling
(ii) Soft water lathers with soap but hard water not.
What characteristics do you expect from an electron-deficient hydride with respect to its structure and chemical reaction?
Arrange the following:
(i) CaH2, BeH2 and TiH2 in order of increasing electrical conductance.
(ii) LiH, NaH and CsH in order of increasing ionic character.
(iii) H-H, D—D and F—F in order of increasing bond dissociation enthalpy.
(iv) NaH, MgH2 and H2O in order of increasing reducing property.
Is demineralised or distilled water useful for drinking purposes? If not, how can it be made useful ?
When sodium peroxide is treated with dilute sulphuric acid, we get .
(a) sodium sulphate and water
(b) sodium sulphate and oxygen
(c) sodium sulphate, hydrogen and oxygen
(d) sodium sulphate and hydrogen peroxide.
Which of the following equatibns depicts the oxidizing nature of H202?
(a) 2Mn0–4 + 6H+ + 5H202 → 2Mn2+ + 8H20 + 502
(b) 2Fe3+ + 2H+ + H202 → 2Fe2+ + 2H20 + 02
(c) 2I– + 2H+ + H202 → I2 + 2H20
(d) KI04 + H202 → KI03 + H20 + 02
Saline hydrides are known to react with water violently producing fire. Can C02, a well known fire extinguisher, be used in this case? Explain.
Account for the following:
(i) dihydrogen gas is not preferred in balloons.
(ii) Cone. H2S04 cannot be used for drying H2.
Account for the following:
(a) Can phosphorus with electronic configuration 3s2 3p3 form PH5?
(b) Water is responsible for moderation of body temperature. How?
(c) Hard water is not suitable for boilers as well as for laundary.
Hardness of water may be temporary or permanent. Permanent hardness is due to the presence of
(a) Chlorides of Ca and Mg in water
(b) Sulphate of Ca and Mg in water
(c) Hydrogen carbonates of Ca and Mg in water
(d) Carbonates of alkali metals in water.
Which of the following hydrides is electron-precise hydride?
(a) B2H6
(b) NH3
(c) H20
(d) CH4
Which of the following reactions is an example of use of water gas in the synthesis of other compounds?
What do you understand by (i) Electron-deficient (ii) Electron-precise (iii) Electron-rich compounds of hydrogen? Provide justification with suitable examples.
How can production of hydrogen from water gas be increased by using water gas shift reaction?
(i)Draw the gas phase and solid phase structure of H202.
(ii) H202 is a better oxidizing agent than water. Explain.
Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.
Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?
What do you understand by the term ‘non-stoichiometric hydrides’? Do you expect this type of hydrides to be formed by alkali metals? Justify your answer.
Complete the following chemical reactions.
(i) PbS(s) + H2O2 (aq) ————->
(ii) MnO4– (aq) + H2O2 (aq) ————->
(iii) CaO(s) + H2O(g) ————->
(iv) AlCl3(g) + H2O(l)————->
(v) Ca3N2(S) + H2O(l) ————->
Classify the above into (a) hydrolysis, (b) redox and (c) hydration reactions.
What do you expect the nature of hydrides is, if formed by elements of atomic numbers 15,19, 23 and 44 with dihydrogen? Compare their behaviour towards water.
What do you understand by the terms:
(i) Hydrogen economy (ii) hydrogenation (iii) syngas (iv) water-gas shift reaction
(v) fuel-cell?
Which gas is evolved when Mg3N2 (Magnesium nitride) is treated with H2O? Give chemical reaction.