Answer:
0.084 M
Explanation:
Using the Henderson-Hasselbalch equation for a buffer ( a buffer is solution contain a weak acid and it conjugate base; the solution resist change in pH)
pH = pKa + log ( base/acid)
4.9 - 4.76 =log ( base / acid)
10^0.14 = ( base / acid)
1.38 = (base / acid)
since there is 0.2 M in the buffer solution
the concentration of acid = × 0.2 = 0.084 M
Answer: 0.462 moles
Explanation: 13C indicates an isotope of carbon and its mass number is 13. It means the mass of 1 mol of 13C is 13 gram.
The question asks to calculate the number of atoms present in 6.00 grams of 13C.
To calculate the number of moles we divide the given grams by the mass of 1 mol of the element. The set could be shown easily using dimensional analysis as:
= 0.462 moles
So, there will be 0.462 moles of atoms in 6.00 grams of 13C.