Answer:
3.6
Explanation:
Step 1: Given data
- Concentration of formic acid: 0.03 M
- Concentration of formate ion: 0.02 M
- Acid dissociation constant (Ka): 1.8 × 10⁻⁴
Step 2: Calculate the pH
We have a buffer system formed by a weak acid (HCOOH) and its conjugate base (HCOO⁻). We can calculate the pH using the <em>Henderson-Hasselbach equation</em>.
![pH = pKa +log\frac{[base]}{[acid]} = -log 1.8 \times 10^{-4} + log \frac{0.02}{0.03} = 3.6](https://tex.z-dn.net/?f=pH%20%3D%20pKa%20%2Blog%5Cfrac%7B%5Bbase%5D%7D%7B%5Bacid%5D%7D%20%3D%20-log%201.8%20%5Ctimes%2010%5E%7B-4%7D%20%2B%20log%20%5Cfrac%7B0.02%7D%7B0.03%7D%20%3D%203.6)
Fluorine (F), Chlorine (Cl) and Iodine (I) are all found in the same group on the Periodic Table because they have similar physical properties. Since they are all Halogens, they have 7 valence electrons in their outer shell. In order to get a total of 8, they naturally combine with elements of the same isotope (itself), so D comes close to being correct, but it's not the best answer choice.
The answer is D: studying how the mayfly population affects the number of trout in a stream <span> As the science of ecology studies interactions between individual organisms and their environments.</span>
Given the number of a substance, we can solve the number of moles by using a conversion factor that would relate the number of a substance to the number of moles. In any case, Avogadro's number would be used. It <span>represents the number of
units in one mole of any substance. This has the value of 6.022 x 10^23 units /
mole. This number can be used to convert the number of atoms or molecules into
number of moles. For example, we are given 1.23 x 10^24 atoms of a substance converting it to moles we do as follows:
</span>1.23 x 10^24 atoms ( 1 mol / 6.022x10^23 atoms ) = 2.04 moles
