The heat of combustion of carbon to CO2 is –393.5 KJ/mol. The heat released upon the formation of 35.2 g of CO2 from carbon and oxygen gas is:
1. –315 KJ
2. +315 KJ
3. –630 KJ
4. +630 KJ

Subtopic:  Thermochemistry |
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NEET - 2015
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Consider the following reactions:

 (i) H+(aq) + OH-(aq) → H2O(l) ΔH = -x1 kJmol-1 (ii) H2(g) + 1/2O2(g) → H2O(l) ΔH = -x2 kJmol-1 (iii) CO2(g) + H2(g) → CO (g) + H2O(l) ΔH = -x3 kJmol-1 (iv) C2H2(g) + 5/2O2(g) →  2CO2 + H2O(l) ΔH = -x4 kJmol-1

Enthalpy of formation of H2O(l) is :

1. $-{x}_{3}$ $kJ$ $mo{l}^{-1}$

2. $-{x}_{4}$ $kJ$ $mo{l}^{-1}$

3. $-{x}_{1}$ $kJ$ $mo{l}^{-1}$

4. $-{x}_{2}$ $kJ$ $mo{l}^{-1}$

Subtopic:  Thermochemistry |
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AIPMT - 2007
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 Assertion (A): All combustion reactions are exothermic. Reason (R): For an exothermic reaction, enthalpies of products are greater than enthalpies of reactants $${(\Sigma v_p\Delta_fH(P)> \Sigma v_R\Delta_fH(R))}$$.

 1 Both (A) and (R) are true and (R) is the correct explanation of (A). 2 Both (A) and (R) are true but (R) is not the correct explanation of (A). 3 (A) is true but (R) is false. 4 (A) is false but (R) is true.

Subtopic:  Thermochemistry |
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$$\Delta_fH^\circ$$ is non-zero for which of the following species?
1. $$S_\text{monoclinic}$$
2.  $$C_\text{graphite}$$
3. H2(g)
4.  $$O_2(g)$$
Subtopic:  Thermochemistry |
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Given, the following reaction:

Given:  ∆ H= 109 kJ/mol

B.E. of (N-N) = 163 kJ/mol

B.E. of (N-H) = 391 kJ/mol

B.E. of (H-H) = 436 kJ/mol

Calculate the bond enthalpy of N = N.

1. 182 kJ/mol

2. 400 kJ/mol

3. 300 kJ/mol

4. 218 kJ/mol

Subtopic:  Thermochemistry |
72%
From NCERT