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2 years ago

What is the electron shielding effect? What is the trend for it? How and why does it happen?

Chemistry

1 answer:

andriy [413]2 years ago

6 0

Answer:

See explanation

Explanation:

In an atom, the inner electrons may shield the outer electrons from the attractive force of the nucleus. We, refer to this phenomenon as the shielding effect, It is defined as a decrease in the magnitude of attraction between an electron and the nucleus of an atom having more than one electron shell (energy level).

Shielding effect increases down the group due to addition of more shells but decreases across the period due to the increase in the size of the nuclear charge.

As the magnitude of shielding increases down the group, ionization of electrons becomes easier and the first ionization energies of elements decreases as we move down the group. Since shielding effect decreases across the period, the first ionization energies of elements increases across the period.

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what volume of a 0.149 m potassium hydroxide solution is required to neutralize 17.0 ml of a 0.112 m hydrobromic acid solution?

IgorLugansk [536]

Answer: 12.78ml

Explanation:

Given that:

Volume of KOH Vb = ?

Concentration of KOH Cb = 0.149 m

Volume of HBr Va = 17.0 ml

Concentration of HBr Ca = 0.112 m

The equation is as follows

HBr(aq) + KOH(aq) --> KBr(aq) + H2O(l)

and the mole ratio of HBr to KOH is 1:1 (Na, Number of moles of HBr is 1; while Nb, number of moles of KOH is 1)

Then, to get the volume of a 0.149 m potassium hydroxide solution Vb, apply the formula (Ca x Va)/(Cb x Vb) = Na/Nb

(0.112 x 17.0)/(0.149 x Vb) = 1/1

(1.904)/(0.149Vb) = 1/1

cross multiply

1.904 x 1 = 0.149Vb x 1

1.904 = 0.149Vb

divide both sides by 0.149

1.904/0.149 = 0.149Vb/0.149

12.78ml = Vb

Thus, 12.78 ml of potassium hydroxide solution is required.

5 0

2 years ago

GIVING ALOTS OF POINTS !!! Is the following sentence true or false? Where a river flows in a straight

Neko [114]

Answer: yes true

Explanation: 1. Toward the middle of a river, water tends to flow fastest; toward the margins of the river it tends to flow slowest. 2. In a meandering river, water will tend to flow fastest along the outside bend of a meander, and slowest on the inside bend.

6 0

1 year ago

Which best compares 1 mol of sodium chloride to 1 mol of aluminum chloride?

lesya692 [45]

Mol is the unit of amount of substance. It is equal to 6.02 x 10^23 molecules. Now, One mol of Sodium chloride (NaCl) contains 6.022x 10^23 molecules of NaCl. Also, the number atoms of both Na (sodium) and Cl (chlorine) will be equal. Similatly, One mol of Aluminium Chloride (AlCl3) contains 6.022x 10^23 molecules of (AlCl3) but the ratio of Al and Cl atoms will be 1:3

7 0

2 years ago

HELP!!!! The freezing of methane is an exothermic change. What best describes the temperature conditions that are likely to make

vazorg [7]

Answer: The correct statement is low temperature only, because entropy decreases during freezing.

Explanation:

The relationship between Gibb's free energy, enthalpy, entropy and temperature is given by the equation:

$\Delta G=\Delta H-T\Delta S$

Where,

$\Delta G$ = change in Gibb's free energy

$\Delta H$ = change in enthalpy

T = temperature

$\Delta S$ = change in entropy

It is given that freezing of methane is taking place, which means that entropy is decreasing and $Delta S$ is becoming negative. It is also given that the reaction is an exothermic reaction, this means that the $\Delta H$ is also negative.