Answer:
a. pka = 3,73.
b. pkb = 10,27.
Explanation:
a. Supposing the chemical formula of X-281 is HX, the dissociation in water is:
HX + H₂O ⇄ H₃O⁺ + X⁻
Where ka is defined as:
![ka = \frac{[H_3O^+][X^-]}{[HX]}](https://tex.z-dn.net/?f=ka%20%3D%20%5Cfrac%7B%5BH_3O%5E%2B%5D%5BX%5E-%5D%7D%7B%5BHX%5D%7D)
In equilibrium, molar concentrations are:
[HX] = 0,089M - x
[H₃O⁺] = x
[X⁻] = x
pH is defined as -log[H₃O⁺]], thus, [H₃O⁺] is:
![[H_3O^+]} = 10^{-2,40}](https://tex.z-dn.net/?f=%5BH_3O%5E%2B%5D%7D%20%3D%2010%5E%7B-2%2C40%7D)
[H₃O⁺] = <em>0,004M</em>
Thus:
[X⁻] = 0,004M
And:
[HX] = 0,089M - 0,004M = <em>0,085M</em>
![ka = \frac{[0,004][0,004]}{[0,085]}](https://tex.z-dn.net/?f=ka%20%3D%20%5Cfrac%7B%5B0%2C004%5D%5B0%2C004%5D%7D%7B%5B0%2C085%5D%7D)
ka = 1,88x10⁻⁴
And <em>pka = 3,73</em>
b. As pka + pkb = 14,00
pkb = 14,00 - 3,73
<em>pkb = 10,27</em>
I hope it helps!
Answer:
The molar mass of the protein is 12982.8 g/mol.
Explanation:
The osmptic pressure is given by:
π=MRT
Where,
M: is molarity of the solution
R: the ideal gas constant (0.0821 L·atm/mol·K)
T: the temperature in kelvins
Hence, we look for molarity:
= =5.584×10⁻³mol/l
As we have 2 ml of solution, we can get the moles quantity:
Moles of protein: 5.584×10⁻³
×2ml=1.117×10⁻⁵mol
Finally, the moles quantity is the division between the mass of the protein and the molar mass of the protein, so:
Moles=Mass/Molar mass
Molar mass= Mass/Moles=
=12982.8 g/mol
Answer:
D
Explanation:
The sample must contain impurity that is lower in atomic mass to sodium and since potassium has higher atomic mass to sodium, the answer is the sample contains NaCl and LiCl. We are sure already that the sample is not pure which rules out option a and option b contains sodium iodide which cannot contribute to the increase in chlorine
Although the process varies slightly from one material to another, the general process is as follows:
1) Choose an appropriate container for the solid. This may be a petri dish or a beaker in which you want to prepare the solution of the solid or any other lab equipment.
2) Place the container on a mass balance, then turn the balance on. The mass balance will automatically zero-out the mass of the container, so that any mass that you add on the container will be the mass of the solid. Alternatively, you may first measure the mass of the empty container alone.
3) Add the solid using a lab spatula. The solid should be added more slowly when the reading on the scale comes close to the desired value.
4) Remove the container from the mass balance after the desired amount of solid has been added.
Answer: 
Explanation:
Significant figures : The figures in a number which express the value or the magnitude of a quantity to a specific degree of accuracy is known as significant digits.
Rules for significant figures:
Digits from 1 to 9 are always significant and have infinite number of significant figures.
All non-zero numbers are always significant.
All zero’s between integers are always significant.
All zero’s after the decimal point are always significant.
All zero’s preceding the first integers are never significant.
Thus has three significant figures
