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?
What is the energy in joules, required to shift the electron of the hydrogen atom from the first Bohr orbit to the fifth Bohr orbit and what is the wavelength of the light emitted when the electron returns to the ground state? The ground state electron energy is –2.18 × 10–11 ergs.
The reaction:
CH3CH2I + KOH(aq) → CH3CH2OH + KI
is classified as :
(a) electrophilic substitution
(b) nucleophilic substitution
(c) elimination
(d) addition
Calculate the number of atoms in each of the following
(i) 52 moles of Ar
(ii) 52 u of He
(iii) 52 g of He.
34.05 mL of phosphorus vapour weighs 0.0625 g at 546 °C and 0.1 bar pressure. What is the molar mass of phosphorus?
Why is benzene extra ordinarily stable though it contains three doublebonds?
What would be the SI unit for the quantity pV2T 2/n?
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)
Describe the importance of the following: (i) limestone (ii) cement (iii) plaster of paris.
(i) The energy associated with the first orbit in the hydrogen atom is –2.18 × 10–18 J atom–1. What is the energy associated with the fifth orbit?
(ii) Calculate the radius of Bohr’s fifth orbit for hydrogen atom.
Calculate the wavelength, frequency and wave number of a light wave whose period is 2.0 × 10–10 s.
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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