Instability
Explanation:
Isotopes decays because they are unstable. Stable isotopes do not decay.
- For every atomic nucleus, there is a specific neutron/proton ratio.
- This ratio ensure that a nuclide is stable.
- For example, fluorine F, is 10/9 stable.
- Any nucleus with a neutron/proton combination different from its stability ratio either too many neutrons or too many protons will become unstable.
- Such nuclide will split into one or more other nuclei with the emission of small particles of matter and considerable amount of energy.
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<span>Answer: 8.15s
</span><span />
<span>Explanation:
</span><span />
<span>1) A first order reaction is that whose rate is proportional to the concenration of the reactant:
</span><span />
<span>r = k [N]
</span><span />
<span>r = - d[N]/dt =
</span><span />
<span>=> -d[N]/dt = k [N]
</span><span />
<span>2) When you integrate you get:
</span><span />
<span>N - No = - kt
</span>
<span></span><span /><span>
3) Half life => N = No / 2, t = t'
</span><span />
<span>=> No - No/ 2 = kt' => No /2 = kt' => t' = (No/2) / k
</span><span />
<span>3) Plug in the data given: No = 0.884M, and k = 5.42x10⁻²M/s
</span>
<span /><span /><span>
t' = (0.884M/2) / (5.42x10⁻²M/s) = 8.15s</span>
Answer:
pH = 6.82
Explanation:
To solve this problem we can use the<em> Henderson-Hasselbach equation</em>:
- pH = pKa + log
![\frac{[NaOCl]}{[HOCl]}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BNaOCl%5D%7D%7B%5BHOCl%5D%7D)
We're given all the required data to <u>calculate the original pH of the buffer before 0.341 mol of HCl are added</u>:
- pKa = -log(Ka) = -log(2.9x10⁻⁸) = 7.54
- [HOCl] = [NaOCl] = 0.500 mol / 0.125 L = 4 M
- pH = 7.54 + log
By adding HCl, w<em>e simultaneously </em><u><em>increase the number of HOCl</em></u><em> and </em><u><em>decrease NaOCl</em></u>:
- pH = 7.54 + log
![\frac{[NaOCl-HCl]}{[HOCl+HCl]}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BNaOCl-HCl%5D%7D%7B%5BHOCl%2BHCl%5D%7D)
- pH = 7.54 + log
Answer:
As the amplitude of the sound wave increases, the intensity of the sound increases. Sounds with higher intensities are perceived to be louder. Relative sound intensities are often given in units named decibels (dB).
Explanation:
Answer:
The balanced equation tells us that 1 mole of Zn will produce 1 mole of H2.
1.566 g Zn x (1 mole Zn / 65.38 g Zn) = 0.02395 moles Zn
0.02395 moles Zn x (1 mole H2 / 1 mole Zn) = 0.02395 moles H2 produced
Now use the ideal gas law to find the volume V.
P = 733 mmHg x (1 atm / 760 atm) = 0.964 atm
T = 21 C + 273 = 294 K
PV = nRT
V = nRT/ P = (0.02395 moles H2)(0.0821 L atm / K mole)(294 K) / (0.964 atm) = 0.600 L
