The energy required to excite a hydrogen atom between two energy levels is given by the difference in their energies.
The energy of the nth orbit of a hydrogen atom is given by: \[ E_n = -\frac{13.6}{n^2} { eV} \] For the first excited state (\(n=2\)) and the second excited state (\(n=3\)): \[ E_2 = -\frac{13.6}{2^2} = -3.4 { eV} \] \[ E_3 = -\frac{13.6}{3^2} = -1.51 { eV} \] The energy required to excite the hydrogen atom from the first excited state to the second excited state is the difference: \[ \Delta E = E_3 - E_2 = (-1.51) - (-3.4) = 1.89 { eV} \] Thus, the energy required is 1.89 eV.
For the reaction:
\[ 2A + B \rightarrow 2C + D \]
The following kinetic data were obtained for three different experiments performed at the same temperature:
\[ \begin{array}{|c|c|c|c|} \hline \text{Experiment} & [A]_0 \, (\text{M}) & [B]_0 \, (\text{M}) & \text{Initial rate} \, (\text{M/s}) \\ \hline I & 0.10 & 0.10 & 0.10 \\ II & 0.20 & 0.10 & 0.40 \\ III & 0.20 & 0.20 & 0.40 \\ \hline \end{array} \]
The total order and order in [B] for the reaction are respectively:
\[ f(x) = \begin{cases} x\left( \frac{\pi}{2} + x \right), & \text{if } x \geq 0 \\ x\left( \frac{\pi}{2} - x \right), & \text{if } x < 0 \end{cases} \]
Then \( f'(-4) \) is equal to:If \( f'(x) = 4x\cos^2(x) \sin\left(\frac{x}{4}\right) \), then \( \lim_{x \to 0} \frac{f(\pi + x) - f(\pi)}{x} \) is equal to: