Use the information and data given below to answer the questions • Stronger intermolecular forces result in higher boiling point • Strength of London forces increases with the number of electrons in the molecule • Boiling point of HF ,HCl, HBr and HI are 293K,189K,206K and 238K respectively (a) Which type of intermolecular forces are present in the molecules HCl, HBr and HI? (b) Looking at the trend of boiling points of HCl, HBr and HI, explain, out of dipole interaction and London interaction, which one predominant here? (c) Why is the boiling point of HF highest while that of HCl lowest?

Use the information and data given below to answer the questions
• Stronger intermolecular forces result in higher boiling point
• Strength of London forces increases with the number of electrons in the molecule
• Boiling point of HF ,HCl, HBr and HI are 293K,189K,206K and 238K respectively
(a) Which type of intermolecular forces are present in the molecules HCl, HBr and HI?
(b) Looking at the trend of boiling points of HCl, HBr and HI, explain, out of dipole interaction and London interaction, which one predominant here?
 (c) Why is the boiling point of HF highest while that of HCl lowest?
by

1 Answer

Answer :

Ans :( a) In the molecules HCl, HBr and HI, dipole-dipole interaction and London forces are present. (b) Dipole moment of HCl > HBr > HI but boiling point of HCl < HBr <HI.It means London forces are predominant over dipole-dipole interaction which depends upon surface area.HCl has least surface area, Whereas HI has maximum surface area. (c) HF has highest dipole moment due to highest difference in electronegativity, therefore hydrogen bonding is also present due to which force of attraction will increase, hence it has higher boiling point.
by

Related questions

The boiling points of the halogens increase going from F2 to I2. What type of intermolecular forces are responsible for this trend? w) permanent dipole x) hydrogen bonding y) ion-ion attraction z) London dispersion forces

Description : The boiling points of the halogens increase going from F2 to I2. What type of intermolecular forces are responsible for this trend? w) permanent dipole x) hydrogen bonding y) ion-ion attraction z) London dispersion forces

Last Answer : ANSWER: Z -- LONDON DISPERSION FORCES

Name two intermolecular forces that exist between HF molecules in liquid state.

Description : Name two intermolecular forces that exist between HF molecules in liquid state.

Last Answer : Ans. Dipole-dipole interaction and hydrogen bonding.

Which type of intermolecular forces exists among the following molecules? (a) H2S molecules (b) H2O (c) Cl2 and CCl4 (d) SiH4 (e) Helium (f) He atoms and HCl molecules

Description : Which type of intermolecular forces exists among the following molecules? (a) H2S molecules (b) H2O (c) Cl2 and CCl4 (d) SiH4 (e) Helium (f) He atoms and HCl molecules

Last Answer : Ans. (a) Dipole-Dipole interactions. (b)H-Bond. (c)Dispersion forces. (d)Dispersion forces. (e)Dispersion forces. (f)Induced dipole-dipole interactions.

Define intermolecular forces. Also write down effect of intermolecular forces on melting points & boiling points of substances?

Description : Define intermolecular forces. Also write down effect of intermolecular forces on melting points & boiling points of substances?

Last Answer : The forces of attraction present between the molecules of a compound are called Intermolecular forces''. Effect of intermolecular forces on the m.p and b.p of substances If intermolecular forces of attractions in ... . And if these forces are weak then the m.p and b.p will be relatively lower.

Define (a) Dipole-Dipole Forces (b) Avogadro law (c) Intermolecular forces

Description : Define (a) Dipole-Dipole Forces (b) Avogadro law (c) Intermolecular forces

Last Answer : Ans.(a) Dipole-dipole forces : The force of attraction which act between two molecules having permanent dipoles. (b) Avogadro Law : Equal volumes of all gases under the similar condition of ... . V α n (c) Intermolecular Forces: The forces of attractions and repulsion between interacting particles.

Predict what will happen if intermolecular forces between the molecules are very weak

Description : Predict what will happen if intermolecular forces between the molecules are very weak

Last Answer : Ans. When intermolecular forces are very weak , molecules do not cling together t o make liquid and solid.

Give one example for each of the following types of inter-particle forces (a) London dispersion forces (b)Dipole-Dipole forces (c) Hydrogen bond (d) Ion-dipole forces

Description : Give one example for each of the following types of inter-particle forces (a) London dispersion forces (b)Dipole-Dipole forces (c) Hydrogen bond (d) Ion-dipole forces

Last Answer : Ans. (a) noble gases. (b) between HCl molecules. (c) Between water molecules or HF molecules. (d)Between NO3- and water molecules.

Elaborate the statement that physical state of existence at given conditions is a balance between the thermal energy and intermolecular forces.

Description : Elaborate the statement that physical state of existence at given conditions is a balance between the thermal energy and intermolecular forces.

Last Answer : Ans. Intermolecular forces tend to keep the molecules together but thermal energy of the molecules tends to keep them apart. The three states of matter are the result of the balance between intermolecular forces and thermal energy of the molecules.

Arrange the following in order of decreasing reactivity towards alkanes. HCl, HBr, HI, HF

Description : Arrange the following in order of decreasing reactivity towards alkanes. HCl, HBr, HI, HF

Last Answer : Ans. HI> HBr> HCl >HF

Explain the effect of increasing the temperature of a liquid, on intermolecular forces operating between its particles. What will happen to the viscosity of a liquid if its temperature is increased? Arrange the following in increasing order of viscosity-water, hexane, glycerine.

Description : Explain the effect of increasing the temperature of a liquid, on intermolecular forces operating between its particles. What will happen to the viscosity of a liquid if its temperature is increased? Arrange the following in increasing order of viscosity-water, hexane, glycerine.

Last Answer : Ans. On increasing the temperature , the kinetic energy of liquid molecules increases so that it can overcome the attractive forces between the molecules and hence liquid can flow more easily i.e. viscosity decreases. Order of increasing viscosity : hexane < water < glycerine.

Based on the intermolecular forces involved, which of the following molecules will have the lowest boiling point? w) ethane x) methyl alcohol y) methyl amine z) methyl fluoride

Description : Based on the intermolecular forces involved, which of the following molecules will have the lowest boiling point? w) ethane x) methyl alcohol y) methyl amine z) methyl fluoride

Last Answer : ANSWER: W -- ethane

Which type of intermolecular forces are effected in each of the following process: (i)Sublimation of iodine. (ii)Evaporation of water.

Description : Which type of intermolecular forces are effected in each of the following process: (i)Sublimation of iodine. (ii)Evaporation of water.

Last Answer : Ans. (i) Sublimation of iodine : Dispersion forces. (ii)Evaporation of water : Hydrogen bond.

The number of cornpounds.’elements oxidised by `XeF_2` among following is: HF, HBr, HCl, HI, `NH_3, CrF_2`, Pt, `S_8`

Description : The number of cornpounds.’elements oxidised by `XeF_2` among following is: HF, HBr, HCl, HI, `NH_3, CrF_2`, Pt, `S_8`

Last Answer : The number of cornpounds.’elements oxidised by `XeF_2` among following is: HF, HBr, HCl, HI, `NH_3, CrF_2`, Pt, `S_8`

Which of the following hydrogen halides react with `AgNO_3` to give a precipitate that dissolves in hypo solution ? (I)HCl (II)HF (III)HI (IV)HBr

Description : Which of the following hydrogen halides react with `AgNO_3` to give a precipitate that dissolves in hypo solution ? (I)HCl (II)HF (III)HI (IV)HBr

Last Answer : Which of the following hydrogen halides react with `AgNO_3` to give a precipitate that dissolves in hypo solution ? (I) ... II),(I) D. (II),(IV),(III)

What would happen if dipole develops momentarily in atoms and non polar molecules which are electrically symmetrical?

Description : What would happen if dipole develops momentarily in atoms and non polar molecules which are electrically symmetrical?

Last Answer : Ans. London forces or dispersion forces are developed.

Which of the following cannot be stored in glass bottle? A. Aqua regia B. HF (Answer) C. HCL D. HBr

Description : Which of the following cannot be stored in glass bottle? A. Aqua regia B. HF (Answer) C. HCL D. HBr

Last Answer : B. HF (Answer)

Who has the highest boiling point in HBr & HCl and why ?

Description : Who has the highest boiling point in HBr & HCl and why ?

Last Answer : answer:

More powerful than HF, HCl, HBr ?

Description : More powerful than HF, HCl, HBr ?

Last Answer : HF is more powerful.

Why do alcohols have boiling points much higher than hydrocarbons of similar molecular weight? (a) Alcohols have greater van der Waals attraction forces. (b) Alcohol molecules have greater molecular symmetry. (c) Hydrogen bonds must be broken in the process of volatilization. (d) Alcohols must overcome greater ionic forces in the process of volatilization.

Description : Why do alcohols have boiling points much higher than hydrocarbons of similar molecular weight? (a) Alcohols have greater van der Waals attraction forces. (b) Alcohol molecules have greater ... of volatilization. (d) Alcohols must overcome greater ionic forces in the process of volatilization.

Last Answer : Hydrogen bonds must be broken in the process of volatilization

What is the intermolecular forces in HBr?

Description : What is the intermolecular forces in HBr?

Last Answer : These are dipole-dipole forces.

What is the intermolecular forces in HBr?

Description : What is the intermolecular forces in HBr?

Last Answer : These are dipole-dipole forces.

Give three differences between evaporation and boiling.

Description : Give three differences between evaporation and boiling.

Last Answer : Ans.i) Evaporation occurs at all temperatures while boiling occurs at boiling point. ii) Evaporation is surface phenomenon while boiling occurs throughout the bulk of liquid. iii) Evaporation is slow while boiling is rapid.

Addition of plasticisers to polymers results in partial neutralisation of intermolecular forces of attraction between the macro-molecules thereby increasing its (A) Tensile strength (B) Chemical resistance (C) Flexibility (D) All (A), (B) & (C)

Description : Addition of plasticisers to polymers results in partial neutralisation of intermolecular forces of attraction between the macro-molecules thereby increasing its (A) Tensile strength (B) Chemical resistance (C) Flexibility (D) All (A), (B) & (C)

Last Answer : (C) Flexibility

Define dispersion forces. Write characteristic features of dispersion forces.

Description : Define dispersion forces. Write characteristic features of dispersion forces.

Last Answer : Ans. Dispersion forces: The forces of attraction between two temporary dipoles. Characteristics of dispersion forces: (i) These forces are always attractive. (ii) These forces are effective only at short distance. (iii) Their magnitude depends on the polarisability of the particles

Is the bond energy of all the four C-H bonds in CH4 molecule equal? If not then why ? How is C-H bond energy then reported?

Description : Is the bond energy of all the four C-H bonds in CH4 molecule equal? If not then why ? How is C-H bond energy then reported?

Last Answer : Ans. No because after breaking of C-H bonds one by one, the electronic environments change. The reported value is the average of of the bond dissociation energies of the four C-H bonds.

Why excluded volume ‘b’ is four times the actual volume of the molecules?

Description : Why excluded volume ‘b’ is four times the actual volume of the molecules?

Last Answer : Ans. The two molecules cannot come closer than distance 2r and the volume of sphere with radius 2r is four times the volume of one molecule.

What would have the effect on the gas pressure if collisions between the gas molecules are not elastic?

Description : What would have the effect on the gas pressure if collisions between the gas molecules are not elastic?

Last Answer : Ans. The gas pressure would gradually become zero as molecules will gradually slow down and ultimately settle down due to constant loss of energy.

Surface tension of liquids is the result of which the following: w) interaction of a liquid with its container x) unbalanced forces on the liquid's surface molecules y) adhesive forces of the liquid z) interaction of the liquid's surface molecules and the applied pressure

Description : Surface tension of liquids is the result of which the following: w) interaction of a liquid with its container x) unbalanced forces on the liquid's surface molecules y) adhesive forces of the liquid z) interaction of the liquid's surface molecules and the applied pressure

Last Answer : ANSWER: X -- UNBALANCED FORCES ON THE LIQUID'S SURFACE MOLECULES

How is the strength of hydrogen bond determined?

Description : How is the strength of hydrogen bond determined?

Last Answer : Ans. Strength of H bonding determined by the coulombic interaction between the electronegative atom of one molecule and H atom of other molecule.

i)Vapour pressure increases with increase in temperature. ii)Giycerine is more viscous than water.

Description : i)Vapour pressure increases with increase in temperature. ii)Giycerine is more viscous than water.

Last Answer : Ans. i) At higher temperature inter particle attraction weakens and more number of mole cules escape to vapour. ii) As interparticle forces are stronger in glycerine.

What is the strongest intermolecular force present in liquid ethanol? (a) induced dipole-induced dipole (b) dipole-dipole, specifically hydrogen bonding (c) dipole-dipole, but not hydrogen bonding (d) ion-dipole

Description : What is the strongest intermolecular force present in liquid ethanol? (a) induced dipole-induced dipole (b) dipole-dipole, specifically hydrogen bonding (c) dipole-dipole, but not hydrogen bonding (d) ion-dipole

Last Answer : dipole-dipole, specifically hydrogen bonding

The noble gases have low boiling points because: w) their ionization potentials are very low x) only weak Van der Waals forces hold the atoms together y) they are produced by the fractional distillation of liquid air z) they have eight electrons in the outer shell

Description : The noble gases have low boiling points because: w) their ionization potentials are very low x) only weak Van der Waals forces hold the atoms together y) they are produced by the fractional distillation of liquid air z) they have eight electrons in the outer shell

Last Answer : ANSWER: X -- ONLY WEAK VAN DER WAALS FORCES HOLD THE ATOMS TOGETHER

1. What is the number of electrons in an atom of atomic number Z and mass number A? 2. With which of the following fields is M. F. Hussain associated? 3. Which is the ‘Slack Season’ in the Indian Economy? 4. In which country is Marino sheep rearing the predominant pastoral activity? 5. Which was the lowest unit of Chola administration?

Description : 1. What is the number of electrons in an atom of atomic number Z and mass number A? 2. With which of the following fields is M. F. Hussain associated? 3. Which is the Slack Season' in ... 19. What are Shield volcanoes? 20. Mughal dynasty was to Bahadur Shah Zafar-as what was Lodi dynasty to?

Last Answer : Answer : 1. Z 2. Painting 3. Jan.-June 4. Australia 5. Valanadu 6. Stomata 7. 9th December, 1946 8. Measuring flask 9. China 10. Rajaraja Chola I 11. Vocal music 12. Abidjan 13. ... N. Rao 17. By radiation only 18. Useful but need strict regulation 19. Repeated lava flows 20. Ibrahim Lodi

The distillation carried out in such a way that the liquid with the lowest boiling point is first evaporated and recondensed, then the liquid with the next higher boiling point is then evaporated and recondensed, and so on until all the available liquid fuels are separately recovered in the sequence of their boiling points. Such a process is called  A. cracking  B. carbonisation  C. fractional distillation  D. full distillation

Description : The distillation carried out in such a way that the liquid with the lowest boiling point is first evaporated and recondensed, then the liquid with the next higher boiling point is then evaporated and ... is called  A. cracking  B. carbonisation  C. fractional distillation  D. full distillation

Last Answer : Answer: C

When two ice cubes are pressed together, they join to form one cube. Which one of the following helps to hold them together? (1) Hydrogen bond formation (2) Vander waals forces (3) Covalent attraction (4) Dipole interaction

Description : When two ice cubes are pressed together, they join to form one cube. Which one of the following helps to hold them together? (1) Hydrogen bond formation (2) Vander waals forces (3) Covalent attraction (4) Dipole interaction

Last Answer : (1) Hydrogen bond formation Explanation: When two ice cubes are pressed together, they join to form one cube due to hydrogen bond.

When two ice cubes are pressed together, they join to form one cube. Which one of the following helps to hold them together? (1) Hydrogen bond formation (2) Vander waals forces (3) Covalent attraction (4) Dipole interaction

Description : When two ice cubes are pressed together, they join to form one cube. Which one of the following helps to hold them together? (1) Hydrogen bond formation (2) Vander waals forces (3) Covalent attraction (4) Dipole interaction

Last Answer : Hydrogen bond formation

From thermodynamic point to which system the animals and plants belong?

Description : From thermodynamic point to which system the animals and plants belong?

Last Answer : Ans. Open system.

What is Boyle’s point?

Description : What is Boyle’s point?

Last Answer : Ans. The temperature at which the real gas obeys ideal gas law for an appreciable range of pressure is called Boyle’s point.

(a) What happens when a Ferromagnetic or Ferrimagnetic solid is heated ? (b) The ions of MgO and NaF all have the same number of electrons and intermolecular distance are about the same (235 & 215 pm). Why are the melting points are so different (2642 °C & 992 °C ?

Description : (a) What happens when a Ferromagnetic or Ferrimagnetic solid is heated ?  (b) The ions of MgO and NaF all have the same number of electrons and intermolecular distance are about the same (235 & 215 pm). Why are the melting points are so different (2642 °C & 992 °C ?

Last Answer : (a) It changes into paramagnetic at hight temperature due to randomization of spins.  (b) The ions in MgO carry two unit charges. In NaCl only one unit charge. Hence electrostatic forces of attraction in MgO are stronger.

What type of intermolecular interactions does (CH3CH2)2NH undergo? (a) induced dipole-induced dipole (b) dipole-dipole (c) hydrogen bonding (d) all of these

Description : What type of intermolecular interactions does (CH3CH2)2NH undergo? (a) induced dipole-induced dipole (b) dipole-dipole (c) hydrogen bonding (d) all of these

Last Answer : all of these

Explain why the gas fizzes out when soda water bottle is opened?

Description : Explain why the gas fizzes out when soda water bottle is opened?

Last Answer : Ans. In soda water bottle carbon dioxide gas is dissolved under pressure. As soon as the bottle is opened, the pressure inside the bottle tends to decrease, so the solubility decreases and gas escapes out.

Out of NH3 and N2 which will have a) larger value of ‘a’ b)larger value of ‘ b’ .Explain.

Description : Out of NH3 and N2 which will have a) larger value of ‘a’ b)larger value of ‘ b’ .Explain.

Last Answer : Ans. a) NH3 will have larger value of a because of H – bonding. b) NH3 will have larger value of b due to larger molecular size.

Explain Hess’s law.

Description : Explain Hess’s law.

Last Answer : Ans. It states that the enthalpy change of the reaction remains the same whether the reaction is carried out in one step or several steps, i.e., ∆H = ∆H1 + ∆H2 + ∆H3 +…………

We are consuming a lot of electrical energy, solar energy etc Do you, therefore, conclude that energy of the universe is continuously decreasing? Explain. Which other thermodynamic quantity is continuously increasing or decreasing?

Description : We are consuming a lot of electrical energy, solar energy etc Do you, therefore, conclude that energy of the universe is continuously decreasing? Explain. Which other thermodynamic quantity is continuously increasing or decreasing?

Last Answer : Ans. No, energy of the universe remains constant (law of conservation of energy). Entropy of the universe is continuously increasing.

When ΔH>0 and ΔS< 0, reaction is never spontaneous. Explain.

Description : When ΔH>0 and ΔS< 0, reaction is never spontaneous. Explain.

Last Answer : Ans. When ΔH > 0 , energy factor opposes the reaction . When ΔS< 0, i.e. randomness decreases, this factor also opposes the process. As both factors oppose the process, reaction is never spontaneous.

Define the term system and surroundings. Explain the different types of system.

Description : Define the term system and surroundings. Explain the different types of system.

Last Answer : Ans. System : The part of the Universe which is under investigation. Surroundings: The remaining part of the Universe other than system. The system and surroundings are separated by well defined boundary. Types of system: (i) Open system (ii) Closed system (iii) Isolated system

Explain how can gases be liquefied?

Description : Explain how can gases be liquefied?

Last Answer : Ans. Gases can be liquefied by decrease of temperature and increase of pressure.

Explain the absolute zero (in terms of volume) with the help of isobar.

Description : Explain the absolute zero (in terms of volume) with the help of isobar.

Last Answer : Ans: At absolute zero ,volume approach to zero and below this temperature, the volume will be negative, which is meaningless. Hence absolute zero is the lowest possible temperature .

On the basis of Boyle’s Law explain why mountaineers carry oxygen cylinder with them.

Description : On the basis of Boyle’s Law explain why mountaineers carry oxygen cylinder with them.

Last Answer : Ans. At high altitude as the atmospheric pressure is low , the air is less dense. As a result less oxygen is available for breathing .