2. What is the mass of one mole of Na?

Given bh3, o3, co2, and nh3, which of these compound is an exception to the octet rules?.

Ghella [55]

Answer:

a. BH₃

Explanation:

According to the octet rules, atoms reach stability when are surrounded by eight electrons in their valence shell when they combine to form a chemical compound.

From the options, the only compound in which the central atom does not meet the octet rules is BH₃. The central atom is boron (B), which has 3 electrons in its valence shell. When B is combined with hydrogen (H), 3 electrons from the 3 atoms of H are added. The total amount of electrons is 6, fewer than 8 electrons needed to meet the rule.

hope this helps

5 0

2 years ago

What can you conclude about these two reactions based on the chemical equations? Reaction A: 6CO2(g) + 6H2O(l) + sunlight ? C6H1

OlgaM077 [116]

Given reactions:

(A) 6CO2(g) + 6H2O(l) + sunlight → C6H12O6(aq) + 6O2(g)

(B) 2H2(g) + O2(g) → 2H2O(g) + energy

Exothermic reactions are those which proceed with the release of heat/energy. In contrast, endothermic reactions proceed with the absorption of energy in the form of heat or light.

Since reaction A required sunlight, it is endothermic. Reaction B releases energy, hence exothermic

Ans: (B)

A is endothermic

B is exothermic

8 0

3 years ago

HEEEEELP ASAPP IM AWARDING 30 points!!!!

alexira [117]

Answer:

$\rm S^{2-}$ .

Explanation:

Based on the electron configuration of this ion, count the number of electrons in this ion in total:

$2 + (2 + 6) + (2 + 6) = 18$ .

Each electron has a charge of $(-1)$ .

Atoms are neutral and have $0$ charge. However, when an atom gains one extra electron, it becomes an ion with a charge of $(-1)$ . Likewise, when that ion gains another electron, the charge on this ion would become $(-2)$ .

The ion in this question has a charge of $(-2)$ . In other words, this ion is formed after its corresponding atom gains two extra electrons. This ion has $18$ electrons in total. Therefore, the atom would have initially contained $18 - 2 = 16$ electrons. The atomic number of this atom would be $16$ .

Refer to a modern copy of the periodic table. The element with an atomic number of $16$ is sulphur with atomic symbol $\rm S$ . To denote the ion, place the charge written backwards (" $2-$ " for a charge of $(-2)$ ) as the superscript of the atomic symbol:

$\rm S^{2-}$ .

5 0

3 years ago

Read 2 more answers

Which of the following is an example of acceleration?

anzhelika [568]

Answer:

it's either B. or C.. hope this helps!

Explanation:

4 0

3 years ago

Read 2 more answers

Calculate the concentrations of all species present in a 0.26 M solution of ethylammonium chloride (C2H5NH3Cl).

Alina [70]

Answer:

0.00000223

Explanation:

pKa for C2H5NH3+ = 10.7

pKw = 14.0

pKa + pKb = pKw

10.7 + pKb = 14.0

pKb = 14.0 - 10.7

pKb = 3.30

C2H5NH3Cl is a salt of ethylamine and HCl so it will dissolve in water to produce C2H5NH3^+ + Cl^-

The base hydrolysis reaction: C2H5NH3^+(aq) + H2O(l) <=> C2H5NH2(aq) + H3O^+(aq)

This reaction is described by Kb.

Kb = [C2H5NH2][H3O^+]/[C2H5NH3^+]

Let [C2H5NH2] = [H3O^+] = x,

so [C2H5NH3^+] = 0.26 - x

Kb = x^2/(0.26 - x) = 2.00 x 10^-11

Let's solve for x. In this equation, It is possible to solve without the use quadratic equation. So we can assume that 0.26 - x is approximately equal to 0.26. We won't know until we do the calculation.

We get: x^2 + 2.00 x 10^-11x - 4.99 x 10^-12 = 0

With the use of a quadratic calculator.

x = 2.23 x 10^-6 M = [C2H5NH2] = [H3O^+]

0.26 - x is just 0.26 M in this problem because 2.23 x 10^-6 M is insignificant.

[C2H5NH3^+] = 0.26 M = [Cl^-]

NOTE:

pH = -log [H3O^+] = -log(2.23 x 10^-6) = 5.65

Ka is the acid dissociation constant

Kb is the base dissociation constant

5 0

3 years ago