Explanation:
1
Number of nucleon =
Molarmassofnucleon
Massofatom
=
1.6726×10
−24
g/nucleon
3.32×10
−23
g
=19.8=20(approximately)
It is given that element comprises of 2 atoms
Hence,number of nucleon = 2×20=40
2
You have 4.70 mol H2O
There are two H atoms in 1 molecule H2O.
Therefore, there must be 2*4.70 = 9.40 mols H in 4.70 mols H2O.
How many mols O in 4.70 mols H2O? That's 4.70 mols, of course.
Said another way, you have 2 mols H for every 1 mol H2O and 1 mol O for every 1 mol H2O.
So for 50 mols H2O you have 100 mols H and 50 mol O.
Because it tilts on its axis
Answer:
The most effective buffer at pH 9.25 will be a mixture of 1.0 M NH3 and 1.0 M NH4Cl
Explanation:
Step 1: Data given
pH of a buffer = pKa + log ([A-]/[Ha])
a mixture of 1.0 M HC2H3O2 and 1.0 M NaC2H3O2 (Ka for acetic acid = 1.8 x 10-5)
pH = -log( 1.8 * 10^-5) + log (1/1)
pH = -log( 1.8 * 10^-5)
pH = 4.74
a mixture of 1.0 M NaCN and 1.0 M KCN (Ka for HCN = 4.9 x 10-10)
pH = -log( 4.9 * 10^-10) + log (1/1)
pH = -log( 1.8 * 10^-5)
pH = 9.30
a mixture of 1.0 M HCl and 1.0 M NaCl
The solution made from NaCl and HCl will NOT act as a buffer.
HCl is a strong acid while NaCl is salt of strong acid and strong base which do not from buffer solutions hence due to HCl PH is less than 7.
a mixture of 1.0 M NH3 and 1.0 M NH4Cl (Kb for ammonia = 1.76 x 10^-5)
Ka * Kb = 1*10^-14
Ka = 10^-14 / 1.76*10^-5
Ka = 5.68*10^-10
pH = -log( 5.68*10^-10) + log (1/1)
pH = -log( 5.68*10^-10)
pH = 9.25
The most effective buffer at pH 9.25 will be a mixture of 1.0 M NH3 and 1.0 M NH4Cl
