Who is credited with creating the first periodic table

According to VSEPR theory, if there are three electron domains in the valence shell of an atom, they will be arranged in a(n) __

wolverine [178]

Answer: B. trigonal planar

Explanation:

Valence Shell Electron Pair Repulsion Theory (VSEPR) is a model to predict the geometry of the atoms making up a molecule where atoms are arranged such that the forces of repulsion are minimum.

If a central atom is bound to three electron domains ,the number of electron pairs is 3, that means the hybridization will be $sp^2$ and the electronic geometry of the molecule will be trigonal planar as the electron pairs will repel each other and attain a position which is most stable.

Example: $BCl_3$ with 3 electron domains has trigonal planar geometry.

6 0

3 years ago

What is the pH of a solution of KOH with a hydroxide concentration of [OH⁻] = 1.10 x 10⁻⁴

olga2289 [7]

Answer:

$p[H+] = 10.042$

Explanation:

As we know that

$pKw = pH + pOH$ ......eq (1)

we will calculate the pH of OH- and then we will calculate the pH of H+

So p[OH-] $= - log [1.10 * 10^{-4}]$

Solving the right side of the equation, we get

p[OH-]

$= - [-3.958]\\= 3.958$

Now we know that

$pKw = 14.0$

Substituting the value of pOH in the above equation, we get -

$14.0 = p[H+] + 3.958\\p[H+] = 14 - 3.958\\p[H+] = 10.042$

3 0

3 years ago

Dumbledore decides to gives a surprise demonstration. He starts with a hydrate of Na2CO3 which has a mass of 4.31 g before heati

vovikov84 [41]

Answer:

Na₂CO₃.2H₂O

Explanation:

For the hydrated compound, let us denote is by Na₂CO₃.xH₂O

The unknown is the value of x which is the amount of water of crystallisation.

Given values:

Starting mass of hydrate i.e Na₂CO₃.xH₂O = 4.31g

Mass after heating (Na₂CO₃) = 3.22g

Mass of the water of crystallisation = (4.31-3.22)g = 1.09g

To determine the integer x, we find the number of moles of the anhydrous Na₂CO₃ and that of the water of crystallisation:

Number of moles = $\frac{mass }{molar mass }$

Molar mass of Na₂CO₃ =[(23x2) + 12 + (16x3)] = 106gmol⁻¹

Molar mass of H₂O = [(1x2) + (16)] = 18gmol⁻¹

Number of moles of Na₂CO₃ = $\frac{3.22}{106}$ = 0.03mole

Number of moles of H₂O = $\frac{1.09}{18}$ = 0.06mole

From the obtained number of moles:

Na₂CO₃ H₂O

0.03 0.06

Simplest

Ratio 0.03/0.03 0.03/0.06

1 2

Therefore, x = 2

7 0

3 years ago

Which of the following best explains velocity?

zhannawk [14.2K]

Velocity is explained as the *speed and *direction something might move. Speed means moving and Direction means a certain way (not stationary.)

Hope this helps!

8 0

3 years ago

I don't quite understand it

irina1246 [14]

So, you need to have same ammount of atoms on the left and on the right side of the equation. You need to count the ammount of attoms of every substance on the left, and make sure that on the right side the ammount is same. For example in the 1st one it’s 6Sn+2P4=2Sn3P4, so that you have 6atoms of Sn on the left and 6 atoms of Sn on the right, same with the P

6 0

3 years ago