Answer:
Mass = 2.16 g
Explanation:
Given data:
Number of molecules of F₂ = 3.45 × 10²²
Mass in gram = ?
Solution:
Avogadro number:
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
1 mole = 6.022 × 10²³ molecules
3.45 × 10²² molecules ×1 mol / 6.022 × 10²³ molecules
0.57× 10⁻¹ mol
0.057 mol
Mass in gram :
Mass = number of moles × molar mass
Mass = 0.057 mol × 37.9 g/mol
Mass = 2.16 g
Answer:
Because the optimal range of buffering for a formic acid potassium formate buffer is 2.74 ≤ pH ≤ 4.74.
Explanation:
Every buffer solution has an optimal effective range due to pH = pKa ± 1. Outside this range, there is not enough acid molecules or conjugate base molecules to sustain the pH without variation. There is a certain amount of both molecules that has to be in the solution to maintain a pH controlled.
Being for the formic acid the pKa 3.74, the optimal effective range is between 2.74 and 4.74. Upper or lower these range a formic acid/potassium formate buffer does not work.
There are 115 known elements as of today (Feb. 13, 2016)
so, 'C' is the correct answer
Answer:
Explanation:
Conversion problems could be solved using dimensional analysis for convenient use and understanding. Dimensional analysis is a technique of multiplying the measure we have by a fraction corresponding to some two equal measures in different units.
In order to apply dimensional analysis here, we firstly need to know that a prefix 'n' stands for 'nano', and nano means 
. In this case, we have nanoliters. Using the prefix, we can find a relationship between nanoliter and liter:
We may now apply dimensional analysis. Since we wish to convert into liters, we'll be multiplying the number we have in nL by a fraction that contains this relationship with liters in the numerator and nanoliters in the denominator, so that nL terms cancel out and we would obtain the final answer in liters:
