Discuss the shape of the following molecules using the VSEPR model:
BeCl2, BCl3, SiCl4, AsF5, H2S, PH3
Valence shell electron pair repulsion (VSEPR) theory:
It is a model used to predict the 3D geometry of individual molecules from the number of electron pairs surrounding their central atoms. It was developed by Gillespie & Nyholm. The various geometries are as follows according to number of lone pair present:
BeCl2:
The central atom has no lone pair and there are two bond pairs. i.e., BeCl2 is of the type EX2. Hence, it has a linear shape.
BCl3:
The central atom has no lone pair and there are three bond pairs. Hence, it is of the type EX3. Hence, it is trigonal planar.
SiCl4:
The central atom has no lone pair and there are four bond pairs. Hence, the shape of SiCl4 is tetrahedral being the EX4 type molecule.
AsF5:
The central atom has no lone pair and there are five bond pairs. Hence, AsF5 is of the type EX5. Therefore, the shape is trigonal bipyramidal.
H2S:
The central atom has one lone pair and there are two bond pairs. Hence, H2S is of the type AB2E. The shape is Bent.
PH3:
The central atom has one lone pair and there are three bond pairs. Hence, PH3 is of the EX5 type. Therefore, the shape is trigonal bipyramidal.
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?
Pay load is defined as the difference between the mass of displaced air and the mass of the balloon. Calculate the pay load when a balloon of radius 10 m, mass 100 kg is filled with helium at 1.66 bar at 27°C. (Density of air = 1.2 kg m–3 and R = 0.083 bar dm3 K–1 mol–1).
Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040 (assume the density of water to be one).
Calculate the atomic mass (average) of chlorine using the following data:
% Natural Abundance | Molar Mass | |
35Cl | 75.77 | 34.9689 |
37Cl | 24.23 | 36.9659 |
Find out the value of Kc for each of the following equilibria from the value of Kp:
(i) 2NOCl (g) ↔ 2NO (g) + Cl2 (g); Kp = 1.8 × 10–2 at 500 K
(ii) CaCO3 (s) ↔ CaO(s) + CO2(g); Kp = 167 at 1073 K
Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile, E+
(a) Chlorobenzene, 2,4-dinitrochlorobenzene, p-nitrochlorobenzene
(b) Toluene, p-H3C-C6H4-NO2, p-O2N-C6H4-NO2.
Aluminium trifluoride is insoluble in anhydrous HF but dissolves on addition of NaF. Aluminium trifluoride precipitates out of the resulting solution when gaseous BF3 is bubbled through. Give reasons.
Explain tropospheric pollution in 100 words.
Out of benzene, m-dinitrobenzene and toluene which will undergo nitration most easily and why?
A 0.02 M solution of pyridinium hydrochloride has pH = 3.44. Calculate the ionization constant of pyridine
Among the following pairs of orbitals which orbital will experience the larger effective nuclear charge?
(i) 2s and 3s,
(ii) 4d and 4f,
(iii) 3d and 3p
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merci
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What is the shape of XeF4
XeF4. & SF6 shape
Plz explain, CH4 also
why CH4,NH3,H2O are not shown?
PH3 does not have trigonal bipyramidal shape rather it has trigonal pyramidal shape
shape ofch4