(a) Classify following oxides as neutral, acidic, basic or amphoteric:
CO, B2O3, SiO2, CO2, Al2O3, PbO2, Tl2O3
(b) Write suitable chemical equations to show their nature.
(1) CO = Neutral
(2) B2O3 = Acidic
Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium metaborate.
B2O3 + 2NaOH → 2NaBO2 + H2O
(3) SiO2 = Acidic
Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium silicate.
SiO2 + 2NaOH → 2Na2SiO3 + H2O
(4) CO2 = Acidic
Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium carbonate.
CO2 + 2NaOH → 2Na2CO3 + H2O
(5) Al2O3 = Amphoteric
Amphoteric substances react with both acids and bases. Al2O3 reacts with both NaOH and H2SO4.
Al2O3 + 2NaOH → NaAIO2
Al2O3 + 3H2SO4 → Al2(SO4)3 + 3H2O
(6) PbO2 = Amphoteric
Amphoteric substances react with both acids and bases. PbO2 reacts with both NaOH and H2SO4.
PbO2 + 2NaOH → Na2PbO3 + H2O
PbO2 + 2H2SO4 → 2PbSO4 + 2H2O +O2
(7) Tl2O3 = Basic
Being basic, it reacts with acids to form salts. It reacts with HCl to form thallium chloride.
Tl2O3 + 6HCl → 2TlCl3 + 3H2O
The mass of an electron is 9.1 × 10–31 kg. If its K.E. is 3.0 × 10–25 J, calculate its wavelength.
Calculate the amount of carbon dioxide that could be produced when
(i) 1 mole of carbon is burnt in air.
(ii) 1 mole of carbon is burnt in 16 g of dioxygen.
(iii) 2 moles of carbon are burnt in 16 g of dioxygen.
Calculate the wavelength of an electron moving with a velocity of 2.05 × 107 ms–1.
Balance the following redox reactions by ion – electron method :
(a) MnO4 – (aq) + I – (aq) → MnO2 (s) + I2(s) (in basic medium)
(b) MnO4 – (aq) + SO2 (g) → Mn2+ (aq) + HSO4– (aq) (in acidic solution)
(c) H2O2 (aq) + Fe 2+ (aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
(d) Cr2O7 2– + SO2(g) → Cr3+ (aq) + SO42– (aq) (in acidic solution)
In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
In a reaction A + B2 → AB2 Identify the limiting reagent, if any, in the following reaction mixtures.
(i) 300 atoms of A + 200 molecules of B
(ii) 2 mol A + 3 mol B
(iii) 100 atoms of A + 100 molecules of B
(iv) 5 mol A + 2.5 mol B
(v) 2.5 mol A + 5 mol B
At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?
Which one of the following will have largest number of atoms?
(i) 1 g Au (s)
(ii) 1 g Na (s)
(iii) 1 g Li (s)
(iv) 1 g of Cl2(g)
Density of a gas is found to be 5.46 g/dm3 at 27 °C at 2 bar pressure. What will be its density at STP?
Give the IUPAC names of the following compounds:
The reaction:
CH3CH2I + KOH(aq) → CH3CH2OH + KI
is classified as :
(a) electrophilic substitution
(b) nucleophilic substitution
(c) elimination
(d) addition
Why is benzene extra ordinarily stable though it contains three doublebonds?
How would you explain the fact that the first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium?
Describe the change in hybridisation (if any) of the Al atom in the following reaction.
A large number of fish are suddenly found floating dead on a lake. There is no evidence of toxic dumping but you find an abundance of phytoplankton. Suggest a reason for the fish kill.
Nitric oxide reacts with Br2 and gives nitrosyl bromide as per reaction given below:
2NO (g) + Br2 (g) ↔ 2NOBr (g)
When 0.087 mol of NO and 0.0437 mol of Br2 are mixed in a closed container at constant temperature, 0.0518 mol of NOBr is obtained at equilibrium. Calculate equilibrium amount of NO and Br2 .
Beryllium and magnesium do not give colour to flame whereas other alkaline earth metals do so. Why?
(i) Calculate the number of electrons which will together weigh one gram.
(ii) Calculate the mass and charge of one mole of electrons.
If the position of the electron is measured within an accuracy of + 0.002 nm, calculate the uncertainty in the momentum of the electron. Suppose the momentum of the electron is h/4πm × 0.05 nm, is there any problem in defining this value.