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alexira
11 days ago
15

The standard curve was made by spectrophotographic analysis of equilibrated iron(III) thiocyanate solutions of known concentrati

on. You are asked to analyze a Fe(SCN)2+ solution with an unknown concentration and an absorbance value of 0.410 . The slope-intercept form of the equation of the line is y=4541.6x+0.0461 . The unknown was analyzed on the same instrument as the standard curve solutions at the same temperature. What is the Fe3+ concentration of the unknown solution?
Chemistry
1 answer:
VMariaS [1K]11 days ago
6 0

Answer:

The molar concentration of Fe³⁺ in the unknown solution is 8.01x10⁻⁵M.

Explanation:

When creating a calibration curve in spectrophotometric analysis, you apply Lambert-Beer’s law, which indicates that the absorbance of a compound is directly related to its concentration:

A = E*l*C

Where A stands for absorbance, E is the molar absorption coefficient, l is the path length, and C represents the molar concentration

Using the line equation, you find:

y = 4541.6X + 0.0461

Where Y is the absorbance and X refers to the concentration - we will presume the concentration is expressed in molarity-

Given that the absorbance of the unknown is 0.410:

0.410 = 4541.6X + 0.0461

X = 8.01x10⁻⁵M

The molar concentration of Fe³⁺ in the unknown solution is 8.01x10⁻⁵M.

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Answer:

Explanation:

Considering the reaction: 2X + 3Y = 3Z, combining 2.00 moles of X with 2.00 moles of Y results in the production of 1.75 moles of Z.

      2 mol       2 mol   1.75 mol

       2X     +    3Y       =    3Z

2 mol is required with 3 mol to yield 3 mol.

3 mol Z / 3 mol Y =  1 to 1

should yield 2 mol Z

1.75 / 2 = 87.5 % production yield

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1 day ago
Given the connection between Aw and K (Aw=2k) could you use the ideal gas law and derive the Boltzmann constant. Water freezes a
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Answer:

Explanation:

The relationship between the new temperature scale and the absolute temperature scale is defined as follows

Aw = 2 K

for K = 273.15 (the freezing point of water on the absolute scale)

Aw = 2 x 273.15 = 546.3 K

Each division of the new scale is equivalent to half that of each division on the absolute scale

each division of the new scale is minimal.

The value of R = 8.314 J per mole per K

Here, per K corresponds to 2Aw

Hence, the value of R in the new scale = 8.314/2 J per mole per Aw

= 4.157 J per mole per Aw

k = R / N

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= .69 x 10⁻²³

= 6.9 x 10⁻²⁴ J per molecule per Aw .

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4 days ago
Write the balanced molecular and net ionic equation for the reaction that occurs when the contents of the two beakers are added
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1) reacting hydrochloric acid with nickel:

Balanced molecular equation: Ni(s) + 2HCl(aq) → NiCl₂(aq) + H₂(g).

Ionic equation: Ni(s) + 2H⁺(aq) + 2Cl⁻(aq) → Ni²⁺(aq) + 2Cl⁻(aq) + H₂(g).

Net ionic equation: Ni(s) + 2H⁺(aq) → Ni²⁺(aq) + H₂(g).

In this reaction, nickel undergoes oxidation, changing from an oxidation state of 0 to +2, while hydrogen is reduced from +1 to 0 (H₂).

2) reacting sulfuric acid with iron:

Balanced molecular equation: Fe(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂(g).

Ionic equation: Fe(s) + 2H⁺(aq) + SO₄²⁻(aq) → Fe²⁺(aq) + SO₄²⁻(aq) + H₂(g).

Net ionic equation: Fe(s) + 2H⁺(aq) → Fe²⁺(aq) + H₂(g).

In this scenario, iron is oxidized from an oxidation state of 0 to +2, while hydrogen experiences reduction from +1 to 0 (H₂).

3) hydrobromic acid reacting with magnesium:

Balanced molecular equation: Mg(s) + 2HBr(aq) → MgBr₂(aq) + H₂(g).

Ionic equation: Mg(s) + 2H⁺(aq) + 2Br⁻(aq) → Mg²⁺(aq) + 2Br⁻(aq) + H₂(g).

Net ionic equation: Mg(s) + 2H⁺(aq) → Mg²⁺(aq) + H₂(g).

This reaction sees magnesium oxidized from 0 to +2, and hydrogen reduced from +1 to 0 (H₂).

4) acetic acid reacting with zinc:

Balanced molecular equation: Zn(s) + 2CH₃COOH(aq) → (CH₃COO)₂Zn(aq) + H₂(g).

Ionic equation: Zn(s) + 2H⁺(aq) + 2CH₃COO⁻(aq) → Zn²⁺(aq) + 2CH₃COO⁻(aq) + H₂(g).

Net ionic equation: Zn(s) + 2H⁺(aq) → Zn²⁺(aq) + H₂(g).

Here, zinc gets oxidized from 0 to +2 (Zn²⁺), while hydrogen is reduced from +1 to 0 (H₂).

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5 days ago
The reaction between nitrogen dioxide and carbon monoxide is NO2(g)+CO(g)→NO(g)+CO2(g)NO2(g)+CO(g)→NO(g)+CO2(g) The rate constan
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Response: The rate constant at 525 K is, 0.0606M^{-1}s^{-1}

Rationale:

Based on the Arrhenius equation,

K=A\times e^{\frac{-Ea}{RT}}

or,

\log (\frac{K_2}{K_1})=\frac{Ea}{2.303\times R}[\frac{1}{T_1}-\frac{1}{T_2}]

where,

K_1 = rate constant when 701K = 2.57M^{-1}s^{-1}

K_2 = rate constant when 525K =?

Ea = activation energy for the process = 1.5\times 10^2kJ/mol=1.5\times 10^5J/mol

R = gas constant = 8.314 J/mole.K

T_1 = initial temperature = 701 K

T_2 = final temperature = 525 K

Substituting the provided values into this formula yields:

\log (\frac{K_2}{2.57M^{-1}s^{-1}})=\frac{1.5\times 10^5J/mol}{2.303\times 8.314J/mole.K}[\frac{1}{701K}-\frac{1}{525K}]

K_2=0.0606M^{-1}s^{-1}

Thus, the rate constant at 525 K is, 0.0606M^{-1}s^{-1}

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2 days ago
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