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3 years ago

As you move from bottom on the periodic table to the top shielding

Chemistry

1 answer:

masha68 [24]3 years ago

3 0

Answer:

AS we move from bottom to top on periodic table shielding decreased.

Explanation:

As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction.

As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.

As we move from bottom to top the energy level decreased because of decreased in electron thus shielding decreased and atomic size also decreased.

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PLEASE HELP!!! PLEASE.

adell [148]

Answer:

Q₁: [HCl] = 0.075 N = 0.075 M.

Q₂: [KOH] = 7.675 mN = 7.675 mM.

Q₃: [H₂SO₄] = 0.2115 N = 0.105 M.

Q₄: The equivalence point is the point at which the added titrant is chemically equivalent completely to the analyte in the sample whereas the endpoint is the point where the indicator changes its color.

Explanation:

Q₁: If it takes 67 mL of 0.15 M NaOH to neutralize 134 mL of an HCl solution, what is the concentration of the HCl?

As acid neutralizes the base, the no. of gram equivalent of the acid is equal to that of the base.

The normality of the NaOH and HCl = Their molarity.

∵ (NV)NaOH = (NV)HCl

∴ N of HCl = (NV)NaOH / (V)HCl = (0.15 N)(67 mL) / (134 mL) = 0.075 N.

∴ The concentration of HCl = 0.075 N = 0.075 M.

Q₂: If it takes 27.4 mL of 0.050 M H₂SO₄ to neutralize 357 mL of KOH solution, what is the concentration of the KOH solution?

As mentioned in Q1, the no. of gram equivalent of the acid is equal to that of the base at neutralization.

The normality of H₂SO₄ = Molarity of H₂SO₄ x 2 = 0.050 M x 2 = 0.1 N.

∵ (NV)H₂SO₄ = (NV)KOH

∴ N of KOH = (NV)H₂SO₄ / (V)KOH = (0.1 N)(27.4 mL) / (357 mL) = 7.675 x 10⁻³ N = 7.675 mN.

∴ The concentration of KOH = 7.675 mN = 7.675 mM.

Q₃:If it takes 55 mL of 0.5 M NaOH solution to completely neutralize 130 mL of sulfuric acid solution (H₂SO₄), what is the concentration of the H₂SO₄ solution?

As mentioned in Q1 and 2, the no. of gram equivalent of the acid is equal to that of the base at neutralization.

The normality of NaOH = Molarity of NaOH = 0.5 N.

∵ (NV)H₂SO₄ = (NV)NaOH

∴ N of H₂SO₄ = (NV)NaOH / (V)H₂SO₄ = (0.5 N)(55 mL) / (130 mL) = 0.2115 N.

∴ The concentration of H₂SO₄ = 0.2115 N = 0.105 M.

Q₄: Explain the difference between an endpoint and equivalence point in a titration.

The equivalence point is the point at which the added titrant is chemically equivalent completely to the analyte in the sample whereas the endpoint is the point where the indicator changes its color.

The equivalence point in a titration is the point at which the added titrant is chemically equivalent completely to the analyte in the sample. It comes before the end point. At the equivalence point, the millimoles of acid are chemically equivalent to the millimoles of base.

End point is the point where the indicator changes its color. It is the point of completion of the reaction between two solutions.

The effectiveness of the titration is measure by the close matching between equivalent point and the end point. pH of the indicator should match the pH at the equivalence to get the same equivalent point as the end point.

6 0

3 years ago

Moles of phosphorous in 15-35-15 fertilizer in 10g

guapka [62]

The composition of a fertilizer is usually express in NPK number. NPK number is in terms of Percent by mass of the said element which are Nitrogen, Phosphorus and Potassium. A 15-35-15 fertilizer has 15% Nitrogen, 35% Phosphorous, and 15% Potassium by mass. If you have 10 g of this fertilizer, to get the number of moles of phosphorus, you multiply the mass by 35%, which is equal to 10*0.35 or 3.5 g phosphorus. Then you divide the calculated mass of phosphorous by its molar mass which is 30.97 g/mol. Therefore, you have 3.5/30.97 which is equal to 0.1130 mol Phosphorus. This is the amount of Phosphorus in moles in the fertilizer.

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3 years ago

What causes polar bonds

yulyashka [42]

Answer:

Bonds are polar when one element in a compound is more electronegative than the other. This creates a dipole in the molecule where one end of the molecule is partially positive and one end is partially negative

Explanation:

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3 years ago

List the subshells that hold the 25 electrons in a manganese atom in order of increasing energy

jonny [76]

Answer:

1s2 2s2 2p6 3s2 3p6 4s2 3d5

Explanation:

According to the Aufbau principle, electrons are filled in orbitals in order of increasing energy. The energy of orbitals in the electronic configuration of manganese increases from left to right, hence 3d orbital is much greater in energy than a 3p orbital.

The arrangement of orbitals in order of increasing energy is shown in the answer above.

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3 years ago

What causes a substance to be hydrophobic?

WITCHER [35]

The hydrophobic effect is caused by nonpolar molecules clumping together. Large macromolecules can have hydrophobic sections, which will fold the molecule so they can be close to each other, away from water. Many amino acids in proteins are hydrophobic, helping the proteins obtain their complicated shapes. The hydrophobic effect extends to organisms, as many hydrophobic molecules on the surface of an organisms help them regulate the amount of water and nutrients in their systems.

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3 years ago