Tamil Nadu Board of Secondary EducationHSC Science Class 11

Define enthalpy of neutralization. - Chemistry


Define enthalpy of neutralization.



The enthalpy of neutralization is defined as the change in enthalpy of the system when one gram equivalent of an acid is neutralized by one gram equivalent of a base or vice versa in dilute solution.

\[\ce{H^+_{(aq)} + OH^-_{(aq)} -> H2O_{(l)}}\] = 57.32 kJ

Concept: Enthalpy (H)
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Chapter 7: Thermodynamics - Evaluation [Page 224]


Tamil Nadu Board Samacheer Kalvi Class 11th Chemistry Volume 1 and 2 Answers Guide
Chapter 7 Thermodynamics
Evaluation | Q II. 11. | Page 224


Select the most appropriate option.

The enthalpy of formation for all elements in their standard states is _______.

Select the most appropriate option.

If the standard enthalpy of formation of methanol is –238.9 kJ mol–1 then entropy change of the surroundings will be _______. 

Select the most appropriate option.

Bond enthalpies of H–H, Cl–Cl, and H–Cl bonds are 434 kJ mol–1, 242 kJ mol–1, and 431 kJ mol–1, respectively. Enthalpy of formation of HCl is _______.

Answer in brief.

Obtain the expression for work done in chemical reaction.

Obtain the relationship between ΔH and ΔU for gas phase reactions.

Answer the following question.

Calculate standard enthalpy of reaction,

Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g), from the following data.

Δf H°(Fe2O3) = - 824 kJ/mol,

Δf H°(CO) = - 110 kJ/mol,

Δf H°(CO2) = - 393 kJ/mol

Answer the following question.

Calculate ΔU at 298 K for the reaction,

C2H4(g) + HCl(g) → C2H5Cl(g), ΔH = - 72.3 kJ

How much PV work is done?

Calculate the amount of work done in the

1) Oxidation of 1 mole HCl(g) at 200 °C according to reaction.

4HCl(g) + O2(g) → 2Cl2(g) + 2H2O(g)

2) Decomposition of one mole of NO at 300 °C for the reaction

2NO(g) → N2(g) + O2(g)

Answer the following question.

Calculate the standard enthalpy of formation of CH3OH(l) from the following data:

CH3OH(l) + `3/2`O2(g) → CO2(g) + 2H2O(l); ΔrH° = - 726 kJ mol-1 

`"C"_("graphite") + "O"_(2("g")) -> "CO"_(2("g"));` ΔrH° = - 393 kJ mol-1

H2(g) + `1/2` O2(g) → H2O(l); ΔrH° = - 286 kJ mol-1

Calculate the work done and comment on whether work is done on or by the system for the decomposition of 2 moles of NH4NO3 at 100 °C
NH4NO3(s) → N2O(g) + 2H2O(g)

Write the mathematical relation between ΔH and ΔU during the formation of one mole of CO2 under standard conditions.

Write the expression showing the relation between enthalpy change and internal energy change for gaseous phase reaction.

An ideal gas expands from the volume of 1 × 10–3 m3 to 1 × 10–2 m3 at 300 K against a constant pressure at 1 × 105 Nm–2. The work done is

The work done by the liberated gas when 55.85 g of iron (molar mass 55.85 g mol–1) reacts with hydrochloric acid in an open beaker at 25°C

Define enthalpy of combustion.

Enthalpy of neutralization is always a constant when a strong acid is neutralized by a strong base: account for the statement.

Derive the relation between ∆H and ∆U for an ideal gas. Explain each term involved in the equation.

Calculate the enthalpy change for the reaction \[\ce{Fe2O3 + 3CO -> 2Fe + 3CO2}\] from the following data.

\[\ce{2Fe + 3/2O2 -> Fe2O3}\]; ΔH = −741 kJ

\[\ce{C + 1/2O2 -> CO}\]; ΔH = −137 kJ

\[\ce{C + O2-> CO2}\]; ΔH = −394.5 kJ

The standard enthalpies of formation of SO2 and SO3 are −297 kJ mol−1 and −396 kJ mol−1 respectively. Calculate the standard enthalpy of reaction for the reaction: \[\ce{SO2 + 1/2O2 -> SO3}\]

What is standard N ≡ N bond enthalpy from following reaction,

\[\ce{N2_{(g)} + 3H2_{(g)} -> 2NH3_{(g)}; \Delta H^0 = - 83 kJ}\]

\[\ce{ΔH^0_{(H-H)}}\] = 435 kJ; \[\ce{ΔH^0_{(N-H)}}\] = 389 kJ

The difference between heats of reaction at constant pressure and at constanl volume for the reaction

\[\ce{2C6H6_{(l)} + 15O2_{(g)} -> 12CO2_{(g)} + 6H2O_{(l)}}\] at 25°C in kJ

When 6.0 g of O2 reacts with CIF as per \[\ce{2ClF_{(g)} + O2_{(g)} -> Cl2O_{(g)} + OF2_{(g)}}\] the enthalpy change is 38.55 kJ. The standard enthalpy of the reaction is ____________.

The enthalpy change for two reactions are given by the equations

\[\ce{2Cr_{(s)} + 1.5 O2_{(g)} -> Cr2O3_{(s)}}\];

∆H1 = −1130 kJ ............(i)

\[\ce{C_{(s)} + 0.5 O2_{(g)} -> CO_{(g)}}\];

∆H2 = −110 kJ .........(ii)

What is the enthalpy change, in kJ, for the following reaction?

\[\ce{3C_{(s)} + Cr2O3_{(s)} -> 2Cr_{(s)} + 3CO_{(g)}}\]

Given the bond energies N ≡ N, H – H and N – H bonds are 945, 436 and 391 kJ/mol respectively. The enthalpy of the reaction;

\[\ce{N2_{(g)} + 3H2_{(g)} -> 2NH3_{(g)}}\]

In which of the following reactions, ∆H is greater than ∆U?

If 2 kJ of heat is released from system and 6 kJ of work is done on the system, what is enthalpy change of system?

For the reaction, \[\ce{N_{2(g)} + 3H_{2(g)} -> 2NH_{3(g)}}\], ΔH is equal to ______.

The work done during combustion of 9 × 10-2 kg of ethane, C2H6 (g) at 300 K is ______.
(Given R = 8.314 J deg-1, atomic mass C = 12, H = 1)

Calculate the work done during the combustion of 0.138 kg of ethanol, C2H5OH(l) at 300 K.
Given: R = 8.314 Jk−1 mol−1, molar mass of ethanol = 46 g mol−1.

Under what conditions ΔH = ΔU?

Calculate the work done in oxidation of so2(g) at 25°C if, \[\ce{2SO_{2(g)} + O2_{(g)} -> 2SO_{3(g)}}\], R = 8.314 J K−1 mol−1.

Calculate ΔS of the surrounding if the standard enthalpy of formation of methanol is − 238.9 kJ mol−1.

In a particular reaction, 2 kJ of heat is released by the system and 8 kJ of work is done on the system. Determine ΔU.

Define enthalpy.


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