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

1 Answer

Answer :

Ans. Dipole-dipole interaction and hydrogen bonding.

Related questions

Description : 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 ... here? (c) Why is the boiling point of HF highest while that of HCl lowest?

Last 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

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

Description : Predict the entropy change in- (i) A liquid crystallizes into solid (ii) Temperature of a crystalline solid raised from 0K to 115K.

Last Answer : Ans. (i) Entropy decreases because molecules attain an ordered state. (ii) Entropy increases because from 0K to 115K average kinetic of moleculesincreases.

Description : What is the effect of temperature on surface tension and viscosity of a liquid?

Last Answer : Ans. Both decrease by increasing temperature.

Description : Why liquid drops are spherical in shape?

Last Answer : Ans. Because of surface tension, the molecules tend to minimize the surface area and sphere has minimum surface area.

Description : Arrange solid, liquid and gas in order of energy. Give reason.

Last Answer : Ans. Solid < liquid < gas. This is because solid absorb energy to change into a liquid which further absorb energy to change into a gas.

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

Description : What intermolecular forces exist in CH3OH?

Last Answer : Need answer

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

Description : State Hess’s law of constant heat summation.Give its two applications.

Last Answer : Ans. Hess's law states that enthalpy change for a reaction is same whether the reaction occurs in single step or several steps. OR If a reaction occurs in several steps then ,its standard enthalpy of ... the formation of the compound (ii) It is used to calculate Lattice enthalpy of an ionic solid.

Description : Give enthalpy (H) of all elements in their standard state.

Last Answer : Ans. In standard state enthalpies of all elements is zero.

Description : What is a thermodynamic state function?

Last Answer : Ans. A function whose value is independent of path. eg. P, V, E, H

Description : State First Law of thermodynamics.

Last Answer : Ans. Energy can neither be created nor destroyed. The energy of an isolated system is constant. ∆U=q+ w.

Description : (i)What are sign conventions used for Heat and Work? (ii).Neither ‘q’ nor ‘w’ is a state function but “ q + w” is a state function. Assign reason.

Last Answer : Ans. (i)Heat absorbed by the system = +ve Heat evolved by the system = -ve Work done by the system = -ve Work done on the system = +ve (ii)ΔU = q + w and ‘∆U’ is a state function, which depends upon initial and final states of the system and not upon its path.

Description : Name the state variables that remain constant in isobaric and isochoric process.

Last Answer : Ans. Pressure and Volume .

Description : (i)State why heat changes in physical and chemical processes are indicated by enthalpy changes and not by entropy changes? (ii)What are the limitations of First Law of thermodynamics?

Last Answer : (i) Most of the processes are carried out in an open system i.e, at constant pressure. (ii)(a) Can’t explain the feasibility of the reaction. (b)It poses no restriction on the direction of flow of heat. (c)Practically it is not possible to convert the heat energy into an equivalent amount of work.

Description : Differentiate between path fuction and state function.

Last Answer : Ans. Path Function : Those properties which depend upon path followed.e.g,work. Sate Function : Those properties which depend upon the initial and final staes of the system and not upon the path followed. E.g, enthalpy.

Description : State First law of thermodynamics. Give its mathematical expression.

Last Answer : Ans. Energy can neither be created nor destroyed but can be transformed from one form to another. ΔU = q + w

Description : State with expression Dalton’s law of partial pressure?

Last Answer : Ans. The total pressure exerted by the mixture of non reactive gases is equal to the sum of the partial pressures of individual gases. Ptotal = p1 + p2 + p3 +…………………

Description : According to you, what are the factors that determine the state of matter

Last Answer : Ans. The factors that determine the different states of the matter are pressure, temperature .

Description : Two ideal gases under same pressure and temperature are allowed to mix in an isolated system. What will be the sign of entropy change?

Last Answer : Ans. Entropy change (∆S) is positive. It is because disorder or degree of freedom increases on mixing.

Description : What are the two faulty assumptions of kinetic theory of gases?

Last Answer : Ans. i) There is no force of attraction and repulsion between the molecules of a gas. ii) Volume of the molecules of a gas is negligibly small in comparison to the empty space between them.

Description : Why is the PH of blood remains almost constant?

Last Answer : Ans: Blood is a buffer solution and resist the change in PH

Description : How much is the percentage ionization of an electrolyte to classified is as 'weak electrolyte'?

Last Answer : Ans:

Description : What is the molarity of pure water?

Last Answer : Ans: 55.5M

Description : What type of substances are generally called 'electrolyte'?

Last Answer : Ans: Acid, bases and salts

Description : Write the effect of temperature on Equilibrium constant.

Last Answer : Ans. The value of Equilibrium constant changes with the temperature. The increase in rate depends upon activation energy .As the activation energy are different for forward & backward direction .So temperature will ... & backward direction. As K= Kf/ Kb ,so the state of equilibrium will be altered.

Description : Why the Equilibrium constant is taken as dimensionless?

Last Answer : Ans. Activities are used in place of molar Conc. These represent the concentration or pressure with respect to standard state.

Description : What will be the effect on equilibrium if (i) a catalyst is added to it (ii) An inert gas is added at constant volume

Last Answer : Ans. (i) The state of equilibrium is not disturbed on adding catalyst rather it is attained quickly. (ii) No effect on state of equilibrium

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.

Description : Applying Le- Chatelier's principle, predict the effect of temperature and pressure on evaporation of water.

Last Answer : Ans Evaporation of water can be represented as water + heat water vapours: i) With increase in pressure- the equilibrium tend to shift in direction where there is decrease in the vol. i.e. ... left. ii) with increase in temperature- the equilibrium shifts to right as it is an endothermic reaction.

Description : Write the significance of equilibrium constant?

Last Answer : Ans.The numerical value of equilibrium constant is a measure of the extent to which the reactants have been converted into products. A large value of K indicates large amount of ... its low value indicates less amount of reactants converted into products before achieving the equilibrium state.

Description : What are the conditions for getting maximum yield of NH3 by Haber’s process?

Last Answer : Ans. High conc. Of N2 &H2, Low Temp. & High Pressure.

Description : What happens to the dissociation of PCl5 in a closed vessel if He gas is introduced into it at the same temperature?

Last Answer : Ans. No effect.

Description : if the equilibrium constant for the reaction is 4.0, what will be the equilibrium constant for the reverse reaction.

Last Answer : Ans. Kc=1/4

Description : Which measurable property become constant in Water Water vapors equilibrium at constant temperature

Last Answer : Ans. Vapour pressure.

Description : what do you mean by homogenous and heterogeneous equilibrium?

Last Answer : Ans. Homogenous;-It is that equilibrium reaction in which all the reactants and the products are in the same phase. Heterogeneous equilibrium: - It is that equilibrium reaction in which all the reactants and the products are in two or more phases

Description : Write Application of Equilibrium constant?

Last Answer : Ans. (i) To predict the extent of the reaction. (ii) To predict the direction of the reaction. (iii) To calculate the equilibrium concentration.