Answer is: concentration of hydrogenium ions is 9,54·10⁻⁵ M.
c(HNO₂) = 0,075 M.
c(NaNO₂) = 0,035 M.
Ka(HNO₂) = 4,5·10⁻⁵.
This is buffer solution, so use <span>Henderson–Hasselbalch equation:
pH = pKa + log(c(</span>NaNO₂) ÷ c(HNO₂)).
pH = -log(4,5·10⁻⁵) + log(0,035 M ÷ 0,075 M).
pH = 4,35 - 0,33.
pH = 4,02.
<span>[H</span>₃O⁺] = 10∧(-4,02).
<span>[H</span>₃O⁺] = 0,0000954 M = 9,54·10⁻⁵ M.
7.32 moles of Chromium is present in 4.41 × 10²⁴ atoms.
<h3>How to find the number of moles ?</h3>
Number of moles = 
<h3>What is Avogadro's Number ?</h3>
Avogadro's number is the number of particles in one mole of substance. 6.022 × 10²³ is known as Avogadro's Constant / Avogadro's Number.
Avogadro's Number = 6.022 × 10²³
Now put the values in above formula we get
Number of moles = 
= 
= 7.32 moles
Thus from the above conclusion we can say that 7.32 moles of Chromium is present in 4.41 × 10²⁴ atoms.
Learn more about the Avogadro's Number here: brainly.com/question/1581342
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Answer:
8.9 g / cm^3
Explanation:
Density = mass / volume
We are given volume which is 10.0cm^3 (cm^3 is just fancy way of saying ml), and mass of 89 gram. Just plug them in respective spots.
Density = 89 / 10.0 = 8.9 g / cm^3