Answer : The mass of sodium fluoride added should be 0.105 grams.
Explanation : Given,
The dissociation constant for HF = 
Concentration of HF (weak acid)= 0.0310 M
First we have to calculate the value of 
.
The expression used for the calculation of is,
Now put the value of 
in this expression, we get:
Now we have to calculate the concentration of NaF.
Using Henderson Hesselbach equation :
![pH=pK_a+\log \frac{[Salt]}{[Acid]}](https://tex.z-dn.net/?f=pH%3DpK_a%2B%5Clog%20%5Cfrac%7B%5BSalt%5D%7D%7B%5BAcid%5D%7D)
![pH=pK_a+\log \frac{[NaF]}{[HF]}](https://tex.z-dn.net/?f=pH%3DpK_a%2B%5Clog%20%5Cfrac%7B%5BNaF%5D%7D%7B%5BHF%5D%7D)
Now put all the given values in this expression, we get:
![2.60=3.17+\log (\frac{[NaF]}{0.0310})](https://tex.z-dn.net/?f=2.60%3D3.17%2B%5Clog%20%28%5Cfrac%7B%5BNaF%5D%7D%7B0.0310%7D%29)
![[NaF]=0.00834M](https://tex.z-dn.net/?f=%5BNaF%5D%3D0.00834M)
Now we have to calculate the moles of NaF.
Now we have to calculate the mass of NaF.
Therefore, the mass of sodium fluoride added should be 0.105 grams.
The isotope is identified as 58 Fe²⁺, where 58 is the mass number of the isotope.
Explanation:
In this problem, there is difference in the number of protons and electrons, but the electron number should not vary in a stable isotope. As isotopes are meant to have difference in number of neutrons leading to change in the mass number. So this means, in the present case the isotope is in oxidized state as the number of electrons is less than the number of protons. This indicates that the isotope is in +2 oxidation state, since the difference in the number of protons and electrons is 2.
Then as an isotope will be formed by varying in the number of neutrons for the elements in periodic table. So from the number of protons we can confirm the atomic number of the element. As the atomic number is given as number of protons in case of oxidized element, the atomic number of 26 in the present case will be related to Fe element in the periodic table.
Hence the isotope will be Fe in +2 oxidation state and having the atomic number as 26 and mass number as 26+32 = 58. So there is a change in the mass number of the isotope of Fe from 56 to 58.
Thus, the isotope is identified as 58 Fe²⁺, where 58 is the mass number of the isotope.
Answer:
Sonic has your answer The atomic mass is the mass of an atom. Although the SI unit of mass is kilogram, the atomic mass is often expressed in the non-SI unit dalton where 1 dalton is defined as ¹⁄₁₂ of the mass of a single carbon-12 atom, at res
Answer:
True
Explanation:
The sedimentary particles from which a sedimentary rock is formed can be derived from a metamorphic, an igneous, or another sedimentary rock. Sedimentary rock can change into metamorphic rock or into igneous rock. Metamorphic rock can change into igneous or sedimentary rock.
