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antiseptic1488 [7]
3 years ago
14

Which statements about the structure of the periodic table are true?

Chemistry
1 answer:
DiKsa [7]3 years ago
3 0

Answer:

The distribution of electrons in energy levels is responsible for the shape of the periodic table.

Explanation:

Henry Moseley in the 1900s re-stated the periodic law by changing the basis of the table to reflect more on the atomic number. The present law is therefore "the properties of elements are a periodic function of their atomic numbers".

Atomic number is the number of electrons in an atom and it is the same as the number of protons for neutral atoms.

In the table, elements having the same number of electrons in the outermost shell of their atoms are placed over one another in vertical columns. Each of the vertical column is known as a group or family while each of the resulting horizontal rows is known as period or row.

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The ph of 0.015 m hno2 (nitrous acid) aqueous solution was measured to be 2.63. what is the value of pka of nitrous acid?
Licemer1 [7]
Nitrous acid<span> dissociates as follows:
</span>
HNO₂(s) ⇄ H⁺(aq) + NO₂⁻(aq) 
           
According to the equation, an acid constant has the following form:

Ka = [H⁺] × [NO₂⁻ ] / [HNO₂] 

From pH, we can calculate the concentration of H⁺ and NO₂⁻:

[H⁺] = 10^-pH = 10^-2.63 = 0.00234 M = [NO₂⁻]

Now, the acid constant can be calculated:

Ka = 0.00234 x 0.00234 / 0.015  = 3.66 x 10⁻⁴

And finally,

pKa = -log Ka = 3.44 


7 0
2 years ago
Write an ionic equation for the reaction of acetic acid with sodium ethoxide, and specify whether the equilibrium favors startin
Elina [12.6K]
<h2>Acetic Acid + Sodium ethoxide ⇄ Butyric Acid + Sodium Hydroxide</h2>

Explanation:

An ionic equation for the reaction of acetic acid with sodium ethoxide is as follows -

  • Reactants -

       Acetic Acid and Sodium ethanolate (sodium ethoxide)

  • Products -

       Butyric Acid and Sodium hydroxide

Hence,

     Acetic Acid + Sodium ethoxide ⇄ Butyric Acid + Sodium Hydroxide

     CH_3COOH + C_2H_5ONa ⇄ CH_3COOC_2H_5 + NaOH

  • Weak acids and bases have low energy than strong acids and bases.
  • The chemical equilibria shift the reaction side with the species having lower energy.
  • Given reaction is an acid-base reaction in which the equilibrium favors the starting material that means it will go to the side of the weakest acid that is acetic acid is weaker than butyric acid.
6 0
2 years ago
A 27.3 g marble sliding to the right at 21.0 cm/s overtakes and collides with a 11.7 g marble moving in the same direction at 12
NISA [10]

Answer:

The answer to this is

The velocity of the 27.3Kg marble after collision is = 16.24 cm/s

Explanation:

To solve the question, let us list out the given variables and their values

Mass of first marble m1 = 27.3g

Velocity of the first marble v1 = 21.0 cm/s

Mass of second marble m2 = 11.7g

Velocity of the second marble v2 = 12.6 cm/s

After collision va1 = unknown and va2 = 23.7 cm/s

From Newton's second law of motion, force = rate of change of momentum produced

Hence m1v1 + m2v2 = m1va1 + m2va2 or

va1 = (m1v1 + m2v2 - m2va2)÷m2 or (720. 72-277.29)÷m1 → va1 = 16.24 cm/s

The velocity of the 27.3Kg marble after collision is = 16.24 cm/s

4 0
3 years ago
What is the wavelength of radiation that has a frequency
White raven [17]

Answer:

\lambda = \frac{c}{\nu}

Explanation:

The wavelenght of  a radiation is inversely proportional to its frequency. It can be estimated by the following formula:

\lambda = \frac{c}{\nu}

Where:

  • \lambda is the wavelenght
  • \nu is the frequency
  • c is the speed of light (arroung 300000 km/s)

5 0
2 years ago
The reaction below demonstrates which characteristic of a base?
svlad2 [7]

Answer: option D. the ability of a base to react with a soluble metal salt.


Justification:


NaOH is a strong base, which means that in water it will dissociate according to this reaction:


  • NaOH(aq) → Na⁺ (aq) + OH⁻ (aq)

On the other hand, CuSO₄ is a soluble ionic salt which in water will dissociate into its ions according to this other reaction:

  • CuSO₄(aq) → Cu²⁺ + SO₄²⁻

Hence, in solution, the sodium ion (Na⁺) will  react with the metal salt in a double replacement reaction, where the highly reactive sodium ion (Na⁺) will substitute the Cu²⁺ in the CuSO₄ to form the sodium sulfate salt, Na₂SO₄ (water soluble), and the copper(II) hydroxide, Cu(OH)₂ (insoluble).


That is what the given reaction represents:


  CuSO₄ (aq)     +     2NaOH(aq)    →    Cu(OH)₂(s)       +     Na₂SO₄(aq)

         ↑                                ↑                         ↑                            ↑

soluble metal salt       strong base       insoluble base       solube salt



5 0
3 years ago
Read 2 more answers
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