Answer:
0,040 M
Explanation:
The global reaction of the problem is:
Al(OH) (s) + OH⁻ ⇄ Al(OH)₂⁻(aq) K= 40
The equation of equilibrium is:
K = ![\frac{[Al(OH)_{2} ^-]}{[Al(OH)][OH^-]}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BAl%28OH%29_%7B2%7D%20%5E-%5D%7D%7B%5BAl%28OH%29%5D%5BOH%5E-%5D%7D)
The concentration of OH⁻ is:
pOH = 14 - pH = <em>3</em>
pOH = -log [OH⁻]
[OH⁻] = 1x10⁻³
Thus:
40 = ![\frac{[Al(OH)_{2} ^-]}{[Al(OH)][1x10^{-3}]}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BAl%28OH%29_%7B2%7D%20%5E-%5D%7D%7B%5BAl%28OH%29%5D%5B1x10%5E%7B-3%7D%5D%7D)
<em>0,04M =
</em>
This means that 0,04 M are the number of moles that the solvent can dissolve in 1L, in other words, solubility.
I hope it helps!
Answer:
a. Interference patterns are observed when a wave passes through a barrier with two slits
Explanation:
Interference is a situation where two waves superimpose to form a new wave of a different amplitude. This amplitude can be greater, same or lower.
the diagram attached below shows the movement of a wave through a barrier with two slits.
you can notice the portions of the wave that overlap. This overlapping of waves is the interference.
Thus, option A is correct.
The other options however, are not correct. as shown below:
Option B is wrong as waves exhibit diffraction <em>(it is diffraction of the light wave that produces the rainbows we see in the sky)</em>
Option C is wrong as waves do not travel straight through slits always.
Option D is wrong as waves can also interfere constructively and destructively.
Answer:
Hint As we know that the concept of mole is mainly to calculate the entities at the microscopic level that is ions, particles, molecules, electrons or atoms etc. It is found that mole is having the symbol mol.
Complete Step by step solution:
- As we are being provided with the information that there is 15 grams of lithium. As we know that the molar mass of lithium is 6.94 g/mol.
- As we know that mole is the amount of substance that has entities as there are atoms exactly in 12 g of carbon isotope. We should note that the number of entities in one mole is important because it is called the Avogadro constant. The numeric value of this constant is 6.022×1023.
- Firstly we will write the given mass as:
156.022×1023
- Now, we can find the number of moles by the formula of moles that is given mass of the substance divided by the molar mass of the substance.
moles=given massmolar mass⟹156.022×10236.94⟹15×6.946.022×1023⟹17.28×10−23moles
- Hence, we can conclude that there are 17.28×1023 moles in 15 grams of lithium.
Note:
- If we want to calculate the number of moles of an individual entity, like say A, that is dissolved in a solution of an entity say B (A+B), then we can do so by using the concept of mole fraction. The formula of mole fraction is given as moles of a substance divided by the total number of moles.
- We should not forget to write the unit after solving the solution. Explanation: