Physical Sciences>Matter and Its Interactions>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.: Overview

This topic covers various concepts like Terms in Second Law of Thermodynamics, , etc.

Important Questions on Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 1

From the data of following bond energies:

$\begin{array}{l} H - H b o n d e n e r g y : 431.37 k J m o l^{- 1} \\ C = C b o n d e n e r g y : 606.10 k J m o l^{- 1} \\ C - C b o n d e n e r g y : 336.49 k J m o l^{- 1} \\ C - H b o n d e n e r g y : 410.50 k J m o l^{- 1} \end{array}$

Calculate the enthalpy of the following reaction in $k J m o l^{- 1}$ .

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 2

Given that bond energies of $H - H and Cl - Cl are 430 kJ {mol}^{- 1} and 240 kJ {mol}^{- 1}$ respectively and ${ΔH}_{f}$ for $HCl is -90 kJ {mol}^{- 1}$ , bond enthalpy of $HCl$ is:

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 3

Consider the following reactions

(i) $H_{(aq)}^{+} + {OH}_{(aq)}^{-} \to H_{2} O (ℓ )$

$Δ H = - X_{1} {k J mol}^{-1}$

(ii) $H_{2} (g) + \frac{1}{2} O_{2} (g) \to H_{2} O (ℓ)$

$Δ H = - X_{2} {k J mol}^{-1}$

(iii) ${CO}_{2} (g) + H_{2} (g) \to CO (g) + H_{2} O (l)$

$Δ H = - X_{3} {k J mol}^{-1}$

(iv) $C_{2} H_{2} (g) + \frac{5}{2} O_{2} (g) \to 2 {CO}_{2} (g) + H_{2} O (ℓ)$

$Δ H = + 4 X_{4} {k J mol}^{-1}$

Enthalpy of formation of $H_{2} O (ℓ)$

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 4

The enthalpy of hydrogenation of cyclohexene is $- 119.5 k J m o l^{- 1} .$ If resonance energy of benzene is $- 150.4 k J m o l^{- 1},$ its enthalpy of hydrogenation of benzene would be

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 5

For which one of the following equations is ${ΔH}_{reaction}^{°}$ equal to ${ΔH}_{f} °$ for the product?

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 6

What is the enthalpy change for,

$2 H_{2} O_{2} (l) \to 2 H_{2} O (l) + O_{2} (g)$ if heat of formation of $H_{2} O_{2} (l) and H_{2} O (l)$ are $- 188$ and $- 286 kJ / mol$ respectively (in standard conditions)?

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 7

Enthalpy of $C H_{4} + \frac{1}{2} O_{2} \to C H_{3} O H$ is negative. If enthalpy of combustion of $C H_{4}$ and $C H_{3} O H$ are x and y respectively, then which relation is correct:

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 8

The values of heat of formation of ${SO}_{2} and {SO}_{3}$ are –298.2 kJ and –98.2 kJ. The enthalpy change of the reaction

${SO}_{2} + \frac{1}{2} O_{2} \to {SO}_{3}$ will be

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 9

Consider the following reaction occurring in automobile

$2 C_{8} H_{18} (ℓ) + {25O}_{2} (g) \to {16CO}_{2} (g) + {18H}_{2} O (g)$

the sign of $ΔH, ΔS and ΔG$ would be:

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 10

Bond dissociation enthalpy of $H_{2}, C l_{2} and H C l are 434, 242 and 431 k J m o l^{- 1}$ respectively. The enthalpy of formation of HCl is:

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 11

A chemical reaction will be spontaneous if it is accompanied by a decrease of

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 12

Assume each reaction is carried out in an open container. For which reaction will $ΔH = ΔE ?$

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 13

The enthalpy and entropy change for the reaction

$B r_{2} (l) + C l_{2} (g) \to 2 B r C l (g)$

are $30 k J m o l^{- 1} a n d 105 J K^{- 1} m o l^{- 1}$ respectively. The temperature at which the reaction will be in equilibrium is

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 14

The absolute enthalpy of neutralisation of the reaction:

${MgO}_{(s)} + 2 {HCl}_{(aq)} \to {MgCl}_{2}_{(aq)} + H_{2} O_{(l)}$ will be:

[Consider the actual value instead of magnitude].

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 15

For the reaction:

$C_{3} H_{8} (g) + 5 O_{2} (g) \to 3 {CO}_{2} (g) + 4 H_{2} O (l)$

at constant temperature, $ΔH - ΔE$ is:

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 16

What is the entropy change (in ${JK}^{- 1} {mol}^{- 1}$ ) when one mole of ice is converted into water at $0 ° C$ ? (The enthalpy change for the conversion of ice to liquid water $6 .0 kJ {mol}^{- 1} at 0 ° C$ )

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 17

$2 mol$ of an ideal gas at $27 ° C$ temperature is expanded reversibly from $2 L$ to $20 L$ . Find the entropy change. $(R = 2 cal / mol K)$

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 18

The entropy change in the fusion of one mole of a solid melting at $27 ° C$ (Latent heat of fusion, $2930 J {mol}^{- 1}$ ) is:

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 19

The Nernst equation for the reaction, $A^{2 +} + 2 e^{-} \to A$ , in terms of the free energy change is:

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Physical Sciences>Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.>Chemical Reactions - The fact that atoms are conserved, together with knowledge of the chemical properties of the elements involved, can be used to describe and predict chemical reactions.> Q 20

Enthalpy of neutralisation of acetic acid by $NaOH$ is $50.6 kJ / mol$ . Calculate $∆ H$ for ionisation of ${CH}_{3} COOH$ . Given the heat of neutralisation of a strong acid with a strong base is $- 55.9 kJ / mol$ .