Q. No.Find the amount of heat released when 35.0 g of CO₂ is formed from the combustion of carbon in dioxygen gas. Given that the enthalpy of combustion of carbon to carbon dioxide is −390.0 kJ mol⁻¹.
| 1. | \(310~\text{kJ}\) | 2. | \(490~\text{kJ}\) |
| 3. | \(245~\text{kJ}\) | 4. | \(700~\text{kJ}\) |
\(\mathrm{A}_2(\mathrm{~g})+3 \mathrm{~B}_2(\mathrm{~g}) \rightarrow 2 \mathrm{AB}_3(\mathrm{~g})\)
If at 300K, the enthalpy change for the above reaction is +15 kJ, then the internal energy change is:
| 1. | 19.98 K J | 2. | 200 J |
| 3. | 1999 J | 4. | 1.9988 kJ |
1. \(\mathrm{\Delta {H}+\Delta {U}=\Delta {nR}} \)
2. \(\mathrm{\Delta {H}=\Delta {U -\Delta n_gRT}}\)
3. \(\mathrm{\Delta {H}=\Delta {U+\Delta n_gRT }}\)
4. \(\mathrm{\Delta {H} -\Delta {U=-\Delta n_gRT}}\)
| 1. | \(\Delta_{\mathrm{r}} \mathrm{H}>0\) and \(\Delta_{\mathrm{r}} \mathrm{S}<0 \) | 2. | \(\Delta_{\mathrm{r}} \mathrm{H}<0\) and \( \Delta_{\mathrm{r}} \mathrm{S}>0 \) |
| 3. | \(\Delta_{\mathrm{r}} \mathrm{H}<0 \) and \(\Delta_{\mathrm{r}} \mathrm{S}<0 \) | 4. | \(\Delta_{\mathrm{r}} \mathrm{H}>0\) and \( \Delta_{\mathrm{r}} \mathrm{S}>0\) |
The standard enthalpy of vaporization for water at 100 oC is 40.66 kJ mol–1. The internal energy of vaporization of water at 100 oC (in kJ mol–1) is:
(Assume water vapour behaves like an ideal gas.)
| 1. | +37.56 | 2. | –43.76 |
| 3. | +43.76 | 4. | +40.66 |
Calculate the H–H bond dissociation energy from the following reaction:
4H(g) → 2H₂(g) ΔH = −869.6 kJ
1. -869.6 kJ
2. +434.8kJ
3. +217.4kJ
4. -434.8 kJ
Consider the following processes:
∆H (kJ/mol)
½ A → B + 150
3B → 2C + D –125
E + A → 2D +350
For B + D → E + 2C, ∆H will be:
1. 325 kJ/mol
2. 525 kJ/mol
3. –175 kJ.mol
4. –325 kJ/mol
The following two reactions are known
The value of H for the following reaction
is:
1. -43.3 kJ
2. -10.3 kJ
3. +6.2 kJ
4. +10.3 kJ
The difference between enthalpy (∆H) and internal energy (∆E) for the given below reaction,
under constant temperature, is:
\(C_{3} H_{8} \left(\right. g \left.\right) + 5 O_{2} \left(\right. g \left.\right) \rightarrow 3 CO_{2} \left(\right. g \left.\right) + 4 H_{2} O \left(\right. l \left.\right)\)
| 1. | + RT | 2. | – 3RT |
| 3. | + 3RT | 4. | – RT |
For the given reaction
, the heat of formations of are -188 kJ/mol & -286 KJ/mol respectively. The change in the enthalpy of the reaction will be:
1. – 196 kJ/mol
2. + 196 kJ/mol
3. + 948 kJ/mol
4. – 948 kJ/mol
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