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3 years ago

Which of the following trends is indirectly proportional to effective nuclear charge, Zeff

Chemistry

2 answers:

Julli [10]3 years ago

7 0

Answer : Option C) Atomic Size

Explanation : The atomic radius of the elements is found to be decreasing if we go from left to right in the modern periodic table. Accordingly, $Z_{eff}$ increases as the number of shielding electrons present in the atomic nucleus of the periodic elements which lies in the same row remains constant while the number of protons in each atomic shell increases.

The effective nuclear charge $Z_{eff}$ of an atom is defined as the net positive charge which is felt by the valence electron of the atomic element.

When $Z_{eff}$ is observed to decrease, it is seen that the atomic radius grows in size. So, it explains the inverse relationship between both. This phenomenon occurs, because there is more screening of the electrons from the nucleus taking place, which is observed due to decrease the attraction between the electron and the nucleus.

ra1l [238]3 years ago

3 0

Periodic trends provides information about an element’s properties. One major trends in the periodic table is the atomic size, which is indirectly proportional to effective nuclear charge. The atomic size gradually decreases from left to right across a periodic table because all electrons are added to the same shell. At the same time, protons are also added to the nucleus, making it more positively charged.

Due to this, there is a greater nuclear attraction; the effect of increasing proton number is greater than that of the increasing electron number, which means that there is a strong attraction of nucleus manifested by pulling the atom's shell closer to the nucleus. Then, the valence electrons are seized closer towards the nucleus of the atom, which resulted to the decrease in atomic radius.

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Igoryamba

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3 years ago

If you weighed out 0.38 g of calcium and reacted it with an excess of hcl, how many moles of h2(g) would you expect to produce?

Hitman42 [59]

Answer is: 0,0095 mol of hydrogen gas will be produced in reaction.
Chemical reaction: Ca + 2HCl → CaCl₂ + H₂.
m(Ca) = 0,38 g.
n(H₂) = ?
n(Ca) = m(Ca) ÷ M(Ca).
n(Ca) = 0,38 g ÷ 40 g/mol
n(Ca) = 0,0095 mol.
from reaction: n(Ca) : n(H₂) = 1 : 1.
n(H₂) = n(Ca) = 0,0095 mol.
n - amount of substance.

4 0

3 years ago

If 13.2 kg of Al 2 O 3 ( s ) , 50.4 kg of NaOH ( l ) , and 50.4 kg of HF ( g ) react completely, how many kilograms of cryolite

Elodia [21]

Answer : The mass of cryolite produced will be, 54.38 kg

Solution : Given,

Mass of $Al_2O_3$ = 13.2 kg = 13200 g

Mass of $NaOH$ = 50.4 kg = 50400 g

Mass of $HF$ = 50.4 kg = 50400 g

Molar mass of $Al_2O_3$ = 101.9 g/mole

Molar mass of $NaOH$ = 40 g/mole

Molar mass of $HF$ = 20 g/mole

Molar mass of $Na_3AlF_6$ = 209.9 g/mole

First we have to calculate the moles of $Al_2O_3,NaOH$ and $HF$ .

$\text{ Moles of }Al_2O_3=\frac{\text{ Mass of }Al_2O_3}{\text{ Molar mass of }Al_2O_3}=\frac{13200g}{101.9g/mole}=129.54moles$

$\text{ Moles of }NaOH=\frac{\text{ Mass of }NaOH}{\text{ Molar mass of }NaOH}=\frac{50400g}{40g/mole}=1260moles$

$\text{ Moles of }HF=\frac{\text{ Mass of }HF}{\text{ Molar mass of }HF}=\frac{50400g}{20g/mole}=2520moles$

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

$Al_2O_3+6NaOH+12HF\rightarrow 2Na_3AlF_6+9H_2O$

From the balanced reaction we conclude that

The mole ratio of $Al_2O_3,NaOH$ and $HF$ is, 1 : 6 : 12

And, the ratio of given moles of $Al_2O_3,NaOH$ and $HF$ is, 129.54 : 1260 : 2520

From this we conclude that, $NaOH,HF$ is an excess reagent because the given moles are greater than the required moles and $Al_2O_3$ is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of $Na_3AlF_6$

From the reaction, we conclude that

As, 1 mole of $Al_2O_3$ react to give 2 mole of $Na_3AlF_6$

So, 129.54 moles of $Al_2O_3$ react to give $129.54\times 2=259.08$ moles of $Na_3AlF_6$

Now we have to calculate the mass of $Na_3AlF_6$

$\text{ Mass of }Na_3AlF_6=\text{ Moles of }Na_3AlF_6\times \text{ Molar mass of }Na_3AlF_6$

$\text{ Mass of }Na_3AlF_6=(259.08moles)\times (209.9g/mole)=54380.892g=54.38kg$

Thus, the mass of cryolite produced will be, 54.38 kg

5 0

3 years ago

Why do people remove entire forests ?

Natasha2012 [34]

Answer:

deforestation not only removes vegetation that is important for removing carbon dioxide from the air.

3 0

4 years ago

Which of the statements is correct? A. Water leaves the descending limb of the loop of Henle through active transport. B. NaCl e

Ivenika [448]

Answer:

The best answer is "E"

NaCl leaves the ascending limb of the loop of Henle through active transport.

Explanation:

The loop of Henle is a U-shaped portion of the tubule that conducts urine within each nephron. It's principal function is the recovery of water and sodium chloride from the urine.

The ascending limb is impermeable to water. NaCl is pumped from the tubule into the interstitium in the ascending limb by active transport. This active transport enables the kidney to establish an osmotic gradient which enables the permeability of water and urea thereby allowing the kidneys to concentrate the urine.

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3 years ago