Answer:
Explanation:
so u can work out the amount of moles of S8 by using
moles=mass/mr
=16/32.1=0.498moles
then use the molar ratio of
S : Fe
1:1 so the moles of Fe is the same 0.498
The use the equation
mass = mr x moles
=55.8 x 0.498
=27.78
so 27.8 g
hope this make sense :)
Answer:
D. Sr < Ca < Be
Step-by-step explanation:
<em>Ionization energ</em>y decreases from top to bottom within a Group, because the valence electrons are further from the nucleus and therefore easier to remove.
Thus, <em>Sr has the lowest</em> ionization energy and <em>Be the highes</em>t.
The correct order is Sr < Ca < Be.
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:
c) H2O and OH−
Explanation:
Acids are the species which furnish hydrogen ions in the solution or is capable of forming bonds with electron pair species as they are electron deficient species.
When an acid donates a proton, it changes into a base which is known as its conjugate base.
Bases are the species which furnish hydroxide ions in the solution or is capable of forming bonds with electron deficient species as they are electron rich species. When a base accepts a proton, it changes into a acid which is known as its conjugate acid.
The acid and the base which is only differ by absence or presence of the proton are known as acid conjugate base pair.
Thus, for the reaction,

The base is
and the conjugate acid of the base is
.
Also, The base is
and the conjugate acid of the base is
.
<u>Correct option is :- c) H2O and OH−</u>
Answer:
Explanation:
Hydrodistillation is a traditional method for the extraction of bioactive compounds from plants. In this method, plant materials are packed in a still compartment then water is added in sufficient amount and brought to a boil. ... The vapor mixture of water and oil is condensed by indirect cooling with water.