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just olya [345]

ANSWER:

4 a) Specific elements have more than one oxidation state, demonstrating variable valency.

For example, the following transition metals demonstrate varied valence states: $Fe^{2+}$ , $Fe^{3+}$ , $Cr^{2+}, Cr^{3+}$ , etc.

Normal metals such as $Pb^{2+} and Pb^{4+}$ also show variable valencies. Certain non-metals are also found to show more than one valence state $Pb^{3+} and Pb^{5+}.$

4 b) Isotopes are members of a family of an element that all have the same number of protons but different numbers of neutrons.

For example, Carbon-14 is a naturally occurring radioactive isotope of carbon, having six protons and eight neutrons in the nucleus. However, C-14 does not last forever and there will come a time when it loses its extra neutrons and becomes Carbon-12.

5 a) $2Fe + 3Cl_2$ → $2FeCl_3$

5 b) $3Pb + 8HNO_3$ → $3Pb (NO_3)_2 + 4H_2O + 2NO_2$

5 c) $Zn + H_2SO_4$ → $ZnSO_4 + H_2$ (already balanced so don't need to change)

5 d) $2H_2 + O_2$ → $2H_2O$

5 e) $2Mg + 2HCl$ → $2MgCl + H_2$

EXPLANATION (IF NEEDED):

1. Write out how many atoms of each element is on the left (reactant side) and right (product side) of the arrow.

2. Start multiplying each side accordingly to try to get atoms of the elements on both sides equal.

EXAMPLE OF BALANCING:

8 0

2 years ago

For the reaction: CH3NH2(aq) + H2O(aq) ⇌ CH3NH3 +(aq) + OH- Determine the change in the pH (ΔpH) for the addition of 6.7 M CH3NH

Korolek [52]

Answer:

The change in the pH (ΔpH) is 2,17

Explanation:

The reaction:

CH₃NH₂(aq) + H₂O(aq) ⇌ CH₃NH₃⁺(aq) + OH⁻

$kb = \frac{[OH^{-}][CH_{3}NH_{3}^+]}{[CH_{3}NH_{2}]}$ (1)

In equilibrium, a solution of CH₃NH₂ 4,7M produces:

[CH₃NH₂] = 4,7 - x

[CH₃NH₃⁺] = x

[OH⁻] = x

Replacing in (1):

$4,38x10^{-4} = \frac{x^2}{4,7-x}$

x² + 4,38x10⁻⁴x - 2,0586x10⁻³ = 0

The solutions are:

x = -0,0456 No physical sense. There are not negative concentrations.

x = 0,04515 Real answer.

The concentration of [OH⁻] is 0,04515 M.

As pOH = -log [OH⁻] And pH+pOH = 14. The pH of this solution is:

pH = 12,65

The addition of 6,7M produce this changes in concentrations:

[CH₃NH₂] = 4,656 + x

[CH₃NH₃⁺] = 6,74515 - x

[OH⁻] = 0,04515 - x

Replacing in (1) you will obtain:

x² - 6,7907x + 0,3025 = 0

Solving for x:

x = 6,74586 No physical sense

x = 0,04484 Real answer.

Thus, [OH⁻] = 0,04515 - 0,044842 = 3,08x10⁻⁴M

pOH = 3,51.

pH = 10,49

Thus ΔpH is 12,65 - 10,49 = 2,16 ≈ 2,17

I hope it helps!

4 0

3 years ago

Calculate the number of moles in 9.22 X 10^23 atom iron

sveta [45]

1.53 moles of Fe is your solution hope it helps!

7 0

2 years ago

Select the correct answer. Which statement best describes how chemical equations demonstrate conservation of mass? O A. The numb

noname [10]

Answer:

Option C )The number of atoms of each element is the same on each side of the equation.

7 0

2 years ago

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A 15.0-L vessel contains 0.50 mol CH4 with a pressure of 1.0 atm. After 0.50 mol C2H6 is added to the vessel, what is the partia

Kazeer [188]

The partial pressure of methane in the mixture of methane and ethane has been 1 atm.

Partial pressure has been the pressure exerted by a gas in the solution or mixture. The partial pressure of each gas has been the total pressure of the gaseous mixture.

The partial pressure of the gas has been dependent on the volume, temperature, and concentration of the gas.

The given methane has a partial pressure of 1 atm in the 15 L vessel. The addition of ethane results in the change in the total pressure of the mixture, as there have been additional moles of solute that contributes to the solution pressure.

However, since there has been no change in the concentration and volume of methane, the pressure exerted by methane has been the same. Thus, the partial pressure of methane has been 1 atm.

For more information about the partial pressure, refer to the link:

brainly.com/question/14623719

7 0

2 years ago

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