Answer:
4.07
Explanation:
There is some info missing. I think this is the original question.
<em>A solution is prepared at 25 °C that is initially 0.057 M in nitrous acid (HNO₂), a weak acid with Ka = 4.5 × 10⁻⁴, and 0.30 M in sodium nitrite (NaNO₂). Calculate the pH of the solution. Round your answer to 2 decimal places.</em>
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Nitrous acid is a weak acid and nitrite (coming from sodium nitrite) is its conjugate base. Together, the form a buffer system. We can calculate its pH using the Henderson-Hasselbach equation.
pH = pKa + log [base]/[acid]
pH = -log 4.5 × 10⁻⁴ + log 0.30/0.057
pH = 4.07
The variable X is the effective nuclear charge, and it remains constant down a group.
Discussion:
The effective nuclear charge is referred to as the actual amount of positive (nuclear) charge experienced by an electron in a polyelectronic atom.
The effective nuclear charge experienced by an electron is otherwise called the core charge.
It is mathematically evaluated as the difference in the atomic number and the core electrons. and since elements in the same group have equal number of Valence electrons, the effective nuclear charge is constant down the group.
Read more on effective nuclear charge:
brainly.com/question/8614020
Explanation:
I hope you interested about the chemical what they add in tea
I think the answer would be d but not 100% sure
Answer:
k = 4.85 x 10⁻³ / s
Explanation:
For a first order reaction we have two very important equations we need to memorize:
ln ( N/N₀ ) = -kt
and,
0.693/ k = t₁/₂
where k is the rate constant and t i is the halflife which can be derived from the first equation.
0.693/ k = t₁/₂ ⇒ k = 0.693 / t₁/₂
k = 0.693 / 143 s = 4.85 x 10⁻³ / s
