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3 years ago

PLEASE HELP!!!

Chemistry

2 answers:

hammer [34]3 years ago

8 0

B. Magnesium + Hydrogen Sulfide (Reactors) ----> Magnesium Sulfide + Hydrogen (Products)

kotykmax [81]3 years ago

8 0

Answer:

B. Mg + $H_{2}S$ ⇒ MgS + $H_{2}$

Explanation:

There are several types of chemical reactions depending on the reaction mechanisms: combination, single-displacement, double-displacement, combustion, decomposition, combustion and redox reactions.

In this case we have a single-displacement reaction, which means that a new chemical species (Mg) replaces other (H) in a given chemical compound ( $H_{2}S$ ). It happens because the electronegativity of H (a nonmetal) is greater than the Mg electronegativity. Thus H attracts the electrons strongly.

That's why there is a transference of electrons from Mg to $H^{+}$ . We can say that Mg reduces $H^{+}$ .

Once $H^{+}$ is reduced to H, a covalent bond is formed between two hydrogen atoms, and then $H_{2}$ is released as a gas.

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Calcula el pH de las siguientes sustancias formadas durante una erupción volcánica:

Virty [35]

Calculate the pH of the following substances formed during a volcanic eruption:

• Acid rain if the [H +] is 1.9 x 10-5

• Sulfurous acid if [H +] = 0.10

• Nitric acid if [H +] = 0.11

<h3>Further explanation </h3>

pH is the degree of acidity of a solution that depends on the concentration of H⁺ ions. The greater the value the more acidic the solution and the smaller the pH.

pH = - log [H⁺]

pH acid rain

$\tt pH=-log[1.9\times 10^{-5}]\\\\pH=5-log1.9\\\\pH=4.72$

pH Sulfurous acid

$\tt pH=-log[10^{-1}]\\\\pH=1$

pH Nitric acid

$\tt pH=-log[11\times 10^{-2}]\\\\pH=2-log~11=0.959$

8 0

2 years ago

Rank the following elements by effective nuclear charge, Zeff, for a valence electron. F LI Be B N

Stels [109]

Answer:

Rank in increasing order of effective nuclear charge:

Li < Be < B < N < F

Explanation:

This explains the meaning of effective nuclear charge, Zeff, how to determine it, and the calculations for a valence electron of each of the five given elements: F, Li, Be, B, and N.

1) Effective nuclear charge definitions

While the total positive charge of the atom nucleus (Z) is equal to the number of protons, the electrons farther away from the nucleus experience an effective nuclear charge (Zeff) less than the total nuclear charge, due to the fact that electrons in between the nucleus and the outer electrons partially cancel the atraction from the nucleus.

Such effect on on a valence electron is estimated as the atomic number less the number of electrons closer to the nucleus than the electron whose effective nuclear charge is being determined: Zeff = Z - S.

2) Z eff for a F valence electron:

F's atomic number: Z = 9
Total number of electrons: 9 (same numer of protons)
Period: 17 (search in the periodic table or do the electron configuration)
Number of valence electrons: 7 (equal to the last digit of the period's number)
Number of electrons closer to the nucleus than a valence electron: S = 9 - 7 = 2
Zeff = Z - S = 9 - 2 = 7

3) Z eff for a Li valence eletron:

Li's atomic number: Z = 3
Total number of electrons: 3 (same number of protons)
Period: 1 (search on the periodic table or do the electron configuration)
Number of valence electrons: 1 (equal to the last digit of the period's number)
Number of electrons closer to the nucleus than a valence electron: S = 3 - 1 = 2
Z eff = Z - S = 3 - 2 = 1.

4) Z eff for a Be valence eletron:

Be's atomic number: Z = 4
Total number of electrons: 4 (same number of protons)
Period: 2 (search on the periodic table or do the electron configuration)
Number of valence electrons: 2 (equal to the last digit of the period's number)
Number of electrons closer to the nucleus than a valence electron: S = 4 - 2 = 2
Z eff = Z - S = 4 - 2 = 2

5) Z eff for a B valence eletron:

B's atomic number: Z = 5
Total number of electrons: 5 (same number of protons)
Period: 13 (search on the periodic table or do the electron configuration)
Number of valence electrons: 3 (equal to the last digit of the period's number)
Number of electrons closer to the nucleus than a valence electron: S = 5 - 3 = 2
Z eff = Z - S = 5 - 2 = 3

6) Z eff for a N valence eletron:

N's atomic number: Z = 7
Total number of electrons: 7 (same number of protons)
Period: 15 (search on the periodic table or do the electron configuration)
Number of valence electrons: 5 (equal to the last digit of the period's number)
Number of electrons closer to the nucleus than a valence electron: S = 7 - 5 = 2
Z eff = Z - S = 7 - 2 = 5

7) Summary (order):

Atom Zeff for a valence electron

Li 1

Be 2

Conclusion: the order is Li < Be < B < N < F

6 0

3 years ago

Help me please omg I don’t know

Anna35 [415]

Answer:

5 1 2 4and 3 this is correct way

8 0

2 years ago

Help plzzzzzzzzzzzzz

tatuchka [14]

Answer:

A: element B

B: element A

C: element B

D: element A

Explanation:

decrease in size leads increase in electronegativity because the smaller the size, the closer the shell is to the nucleus. Also, atomic radius decreases to the right and up on the periodic table. Atomic radius increases to the left and down a period. I hope this helps!

6 0

2 years ago

You wish to make 250. mL of 0.20 M KCl from a stock solution of 1.5 M KCl and DI water.

Nitella [24]

The question requires us to use the dilution formula $M_iV_i=M_fV_f$ , where $M_i$ and $V_i$ are the stock concentration and volume respectively, then $M_f$ and $V_f$ are the dilute concentration and volume respectively.

a. $C_s_t_o_c_k$ = 1.5 M KCI, $C_d_i_l_u_t_e$ =0.20M KCl, $V_d_i_l_u_t_e$ =250ml KCl

b. $M_iV_i=M_fV_f\\\implies V_i= \frac{M_fV_f}{M_i} = \frac{0.20M \times 250ml}{1.5M} = 33.3\ ml$

To prepare the solution 33.3ml of 1.5M KCl is diluted to a total final volume of 250ml.

8 0

3 years ago