Question

In: Chemistry

A certain ionic compound has a ΔH soln = -65.4 kJ/mol. Which of the following conclusions...

A certain ionic compound has a ΔH soln = -65.4 kJ/mol. Which of the following conclusions is correct? A certain ionic compound has a ΔH soln = -65.4 kJ/mol. Which of the following conclusions is correct?

ΔH solute ≈ 0,

ΔH hydration < 0

ΔH solute < ΔH hydration

ΔH solute ≈ ΔH hydration

ΔH solute > ΔH hydration

Solutions

Expert Solution

Heat absorbed or released when a specified amount of a solute dissolves in a certain quantity of solvent at constant pressure is known as enthalphy of solution (Hsolution)

ΔH soln = -65.4 kJ/mol, Here negative shows that heat is released in the process.

Dissolving of ionic compound in water takes place in two steps:

1. Breaking of ionic bonds between ions, this steps involves absorption of heat i.e., endothermic process - Lattice enthalphy

2.Hydration of ions formed (ion dipole of interactions between ions and water molecules). It is a exothermic steps i.e., heat is released- Enthaphy of hydration

Enthalphy of solution will be negative or positive will depends on both the factors discussed.

If the enthalphy of hydration is greater than the lattice enthalpy, it means more heat is released than absorbed. Then enthalphy of solution will be negative.

If the enthalphy of hydration is less than the lattice enthalphy, it means heat released is less than heat absorbed. Then enthalphy of solution will be positive.

We can conclude that in the given case ΔH solute < ΔH hydration


Related Solutions

The ΔH°soln of HNO3 is –33.3 kJ/mol. 10.0 mL of 12.0 M HNO3 is dissolved in...
The ΔH°soln of HNO3 is –33.3 kJ/mol. 10.0 mL of 12.0 M HNO3 is dissolved in 100.0 mL of distilled water initially at 25°C. How much ice at 0°C [Cp = 37.1 J/(mol ·°C), ΔH°fus = 6.01 kJ/mol] must be added to return the solution temperature to 25°C after dissolution of the acid and equilibrium with the ice is reached? The molar heat capacity is 80.8 J/(mol·°C) for the solution, and the molar heat capacity is 75.3 J/(mol·°C) for pure...
The ΔH°soln of HNO3 is –33.3 kJ/mol. 17.0 mL of 13.0 M HNO3 is dissolved in...
The ΔH°soln of HNO3 is –33.3 kJ/mol. 17.0 mL of 13.0 M HNO3 is dissolved in 100.0 mL of distilled water initially at 25°C. How much ice at 0°C [Cp = 37.1 J/(mol ·°C), ΔH°fus = 6.01 kJ/mol] must be added to return the solution temperature to 25°C after dissolution of the acid and equilibrium with the ice is reached? The molar heat capacity is 80.8 J/(mol·°C) for the solution, and the molar heat capacity is 75.3 J/(mol·°C) for pure...
Consider the following set of reactions: N2 + 2O2→N2O4 ,ΔH=−8 kJ/mol N2 + O2→2NO ,ΔH=180 kJ/mol...
Consider the following set of reactions: N2 + 2O2→N2O4 ,ΔH=−8 kJ/mol N2 + O2→2NO ,ΔH=180 kJ/mol The equations given in the problem introduction can be added together to give the following reaction: overall: N2O4→2NO + O2 However, one of them must be reversed, reaction 1: N2 + 2O2→N2O4 What is the enthalpy for reaction 1 reversed? reaction 1 reversed: N2O4→N2 + 2O2 Express your answer numerically in kilojoules per mole. What is the enthalpy for reaction 2?
Calculate the lattice energy (kJ/mol) of the hypothetical ionic compound MX from the information given below....
Calculate the lattice energy (kJ/mol) of the hypothetical ionic compound MX from the information given below. IE1(M) = 499 kJ/mol M(s) => M(g) ΔHo = 70.6 kJ/mol ΔHof(MX) = -147.5 kJ/mol X2(g) => 2X(g) ΔH = 179 kJ EA (X) = -352 kJ/mol IE1 (X) = 271 kJ/mol Answer is  -455 ± 2% Please show all work
The ΔH°rxn for the following reaction is −114.2 kJ/mol. At what temperature (in °C) would the...
The ΔH°rxn for the following reaction is −114.2 kJ/mol. At what temperature (in °C) would the Kc for the reaction be 6.4 x 109? 2NO(g) + O2(g) ↔ 2NO2(g) Kc = 4.9 x 105 at 184°C 271°C 183°C 110°C 74°C
Given the following thermodynamic data, calculate the lattice energy of CsF: ΔH°f[CsF(s)] = -554 kJ/mol ΔH°sublimation...
Given the following thermodynamic data, calculate the lattice energy of CsF: ΔH°f[CsF(s)] = -554 kJ/mol ΔH°sublimation [Cs] = 76.5 kJ/mol Bond energy [F-F] = 159 kJ/mol IE1 (Cs) = 376 kJ/mol EA1 (F) = -328 kJ/mol -1414 kJ/mol -1493 kJ/mol -714 kJ/mol -758 kJ/mol -837 kJ/mol
Use data in Appendix C in the textbook to calculate ΔH∘ in (kJ/mol) , ΔS∘ in...
Use data in Appendix C in the textbook to calculate ΔH∘ in (kJ/mol) , ΔS∘ in (j/mol-K) , and ΔG∘ in (kJ/mol) at 25 ∘C for each of the following reactions: 2P(g)+10HF(g)→2PF5(g)+5H2(g) Appendix C: P(g): dH:316.4; dG: 280.0; S:163.2 HF(g): dH: -268.61; dG: -270.70; S:173.51 PF5(g): dH:-1594.4; dG: -1520.7; S: 300.8 H2(g): dH:217.94; dG: 203.26; S: 114.60
The successive ionization energies of a certain element are: I1 = 899 kJ/mol, I2 =1,757 kJ/mol,...
The successive ionization energies of a certain element are: I1 = 899 kJ/mol, I2 =1,757 kJ/mol, I3= 14,850 kJ/mol, I4 = 21,005 kJ/mol, This pattern of ionization energies suggests that the unknown element is:
A certain substance has a heat of vaporization of 70.78 kJ/mol. At what Kelvin temperature will...
A certain substance has a heat of vaporization of 70.78 kJ/mol. At what Kelvin temperature will the vapor pressure be 6.50 times higher than it was at 331 K?
A certain reaction has an activation energy of 39.79 kJ/mol. At what Kelvin temperature will the...
A certain reaction has an activation energy of 39.79 kJ/mol. At what Kelvin temperature will the reaction proceed 6.50 times faster than it did at 339 K?
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT