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egoroff_w [7]
1 year ago
13

The elements in which electrons are progressively filled in 4f-orbital are called.

Chemistry
1 answer:
Y_Kistochka [10]1 year ago
5 0

The elements in which electrons are progressively filled in 4f-orbital are called lanthanoids.

There are 15 metallic chemical elements called lanthanoids.

Those elements are with atomic numbers from 57 to 71.

Lanthanoids belong to f-block elements because of the filling of the 4f-orbitals.

One of the lanthanoids, lutetium (chemical symbol Lu) has 14 electrons if 4f orbitals.

Electron configuration of lutetium: [Xe] 4f14 5d1 6s2

f-orbitals are similar to the d orbital, but cut in half (eight lobes instead of four).

Lanthanoids are used not as materials in catalysts, alloys, lasers and cathode-ray tubes.

More info about lanthanoids: brainly.com/question/24413965

#SPJ4

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Calculate the osmotic pressure associated with 50.0 g of an enzyme of molecular weight 98 g/mol dissolved in water to give 2600
andrew-mc [135]

Answer:

π = 4,882 atm

Explanation:

To calculate the osmotic pressure (π), the <em>Van´t Hoff equation</em> must be used, which is:

π x V = n x R x T

<em>Where: </em>

• π: Osmotic pressure, which is the difference between the levels of the solution and the pure solvent through a semipermeable membrane, which allows the passage of the solvent but not the solute

• V: Volume of the solution, in liters unit

• n: Number of moles of solute

• R: Constant of ideal gases, equal to 0.08206 L.atm / mol.K

• T: Absolute temperature, in Kelvin degrees

With the data you provide you can calculate the osmotic pressure by clearing it from the equation, we would be equal to:

π = (n x R x T) / V

However, all data must first be converted to the corresponding units in order to replace the values ​​in the equation.

<em>Solution volume ⇒ go from mL to L: </em>

1000 mL of solution ____ 1 L

2600 mL of solution _____ X = 2.6 L

Calculation: 2600 mL x 1 L / 1000 mL = 2.6 L

<em>Temperature ⇒ Go from ° C to K </em>

T (K) = t (° C) + 273.15 = 30.0 ° C + 273.15 = 303.15 K

<em>Number of moles of solute ⇒</em> <em>It can be calculated since we have the mass of the enzyme and its molecular mass: </em>

98.0 g of enzyme ____ 1 mol

50.0 g of enzyme _____ X = 0.510 moles

Calculation: 50.0 g x 1 mol / 98.0 g = 0.510 moles

Now, you can replace the values ​​in the Van´t Hoff equation and you will get the result:

 π = (n x R x T) / V

π = (0.510 mol x 0.08206 L.atm / mol.K x 303.15 K) / 2.6 L = 4.882 atm

Therefore, <em>the osmotic pressure will be 4,882 atm</em>

3 0
3 years ago
Someone please help me:
Stels [109]

Answer: The number to the left of AC should be 6.

Explanation: The balanced chemical reaction is one in which the number of atoms  of each element on the reactant side must be equal to the number of atoms on product side.

The given equation A_2B + DC_3 \rightarrow AC + D_2B_3 is unbalanced as the atoms on the reactant side are not same as number of  atoms on product side. This equation is called as skeletal equation.

The balanced chemical equation is :

3A_2B + 2DC_3 \rightarrow 6AC + D_2B_3

Thus the number to the left of AC is 6.


6 0
2 years ago
Read 2 more answers
Billions of pounds of urea are produced annually for use as a fertilizer. Balance the skeletal equation for the synthesis of ure
klio [65]
2NH₃(g) + CO₂(g) → CO(NH₂)₂(s) + H₂O(l)
is the balanced equation for the synthesis of urea.
5 0
3 years ago
What is the pH of a 0.640 M solution of C₅H₅NHBr (Kb of C₅H₅N is 1.7 × 10⁻⁹)?
Elden [556K]

The pH of a 0.64 M solution of pyridine (C₅H₅N) is 9.52.  

<h3>What is pH ?</h3>

A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid and higher values more alkaline.

The equation for the protonation of the base pyridine is the following:

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻   (1)

Kb = 1.7 × 10⁻⁹ (Given)

To calculate the pH of the solution we need to use the following equation:

pH + pOH = 14

<em>pH = 14 - pOH</em>

     =14 - [-log[OH⁻]]

    = 14 + log[OH⁻]

Now, we need to find the concentration of the OH⁻ ions. Since pyridine is a weak base, at the equilibrium we have (eq 1):

C₅H₅N  +  H₂O  ⇄  C₅H₅NH⁺  +  OH⁻

0.64 - x                          x              x

After entering the values of [C₅H₅N] = 0.64-x, [C₅H₅NH⁺] = x, and [OH⁻] = x, into equation (2) we can find the concentration of OH⁻:

1.7 × 10⁻⁹  =[C₅H₅NH⁺]  [OH⁻]  /  [C₅H₅N]

                = x . x / 0.64-x

1.7 × 10⁻⁹ (0.64-x) - x² = 0

Solving the above quadratic equation for x, we have :

  • x₁ = -3.32 x 10⁻⁵
  • x₂ = 3.32 x 10⁻⁵

Now, We can calculate the pH, after taking the positive value, x₂, (concentrations cannot be negative) and entering into above equation :

<em />

<em>pH = </em>14 + log[OH⁻]

     = 14 + log (3.32 x 10⁻⁵)

 

     = 9.52

Therefore, the pH of the solution of pyridine is 9.52.

Find more about pH here:

brainly.com/question/8834103?referrer=searchResults

#SPJ1

3 0
1 year ago
How many atoms of hydrogen are present: 2(NaHCO3)
Firlakuza [10]

Answer:

《HOPE IT WILL HELP YOU 》

Explanation:

2 Atom of Hydrogen are present in 2 (NaHCO3)

5 0
2 years ago
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