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Doss [256]
3 years ago
10

Question 3 (1 point) The extinction coefficient for copper sulfate in aqueous solution is 12 M-1.cm-1 at 800 nm. If the absorban

ce of the copper sulfate solution in 0.50 cm cuvette is 0.50 at 800 nm, the concentration of copper sulfate in this solution is: O3M O 83 mm 8.3 mm 12 M-cm 0.042 M
Chemistry
1 answer:
Troyanec [42]3 years ago
3 0

Answer:

The concentration of the copper sulfate solution is 83 mM.

Explanation:

The absorbance of a copper sulfate solution can be calculated using Beer-Lambert Law:

A = ε . c . <em>l</em>

where

ε is the extinction coefficient of copper sulfate (ε = 12 M⁻¹.cm⁻¹)

c is its molar concentration (what we are looking for)

l is the pathlength (0.50 cm)

We can use this expression to find the molarity of this solution:

c=\frac{A}{\epsilon.l } =\frac{0.5}{12M^{-1}cm^{-1}0.50cm  } =0.083M=83mM

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Calculate the entropy change for the reaction: Fe2O3(s) +3C(s) -&gt; 2Fe(s) + 3CO(g)
Gelneren [198K]

Answer:

ΔS = +541.3Jmol⁻¹K⁻¹

Explanation:

Given parameters:

Standard Entropy of Fe₂O₃ = 90Jmol⁻¹K⁻¹

Standard Entropy of C = 5.7Jmol⁻¹K⁻¹

Standard Entropy of Fe = 27.2Jmol⁻¹K⁻¹

Standard Entropy of CO = 198Jmol⁻¹K⁻¹

To find the entropy change of the reaction, we first write a balanced reaction equation:

                              Fe₂O₃ +  3C →  2Fe + 3CO

To calculate the entropy change of the reaction we simply use the equation below:

      ΔS = ∑S_{products} - ∑S_{reactants}

Therefore:

     ΔS = [(2x27.2) + (3x198)] - [(90) + (3x5.7)] = 648.4 - 107.1

                          ΔS = +541.3Jmol⁻¹K⁻¹

5 0
2 years ago
Oxygen gas generated in an experiment is collected at 25.0°C in a bottle inverted in a trough of water. The total pressure is 1.
Nitella [24]

Answer:

0.007 mol

Explanation:

We can solve this problem using the ideal gas law:

PV = nRT

where P is the total pressure, V is the volume, R the gas constant, T is the temperature and n is the number of moles we are seeking.

Keep in mind that when  we collect a gas over water we have to correct for the vapor pressure of water at  the temperature in the experiment.

Ptotal = PH₂O + PO₂  ⇒ PO₂ = Ptotal - PH₂O

Since R constant has unit of Latm/Kmol we have to convert to the proper unit the volume and temperature.

P H₂O = 23.8 mmHg x 1 atm/760 mmHg =  0.031 atm

V = 1750 mL x 1 L/ 1000 mL = 0.175 L

T = (25 + 273) K = 298 K

PO₂ = 1 atm - 0.031 atm = 0.969 atm

n =  PV/RT = 0.969 atm x  0.1750 L / (0.08205 Latm/Kmol x 298 K)

n = 0.007 mol

6 0
2 years ago
An object that sticks to iron
Dvinal [7]

Answer:

A magnet

Explanation:

4 0
1 year ago
A 0.245-L flask contains 0.467 mol co2 at 159 °c. Calculate the pressure using the ideal gas law.
lubasha [3.4K]

Answer:

Pressure, P = 67.57 atm

Explanation:

<u>Given the following data;</u>

  • Volume = 0.245 L
  • Number of moles = 0.467 moles
  • Temperature = 159°C
  • Ideal gas constant, R = 0.08206 L·atm/mol·K

<u>Conversion:</u>

We would convert the value of the temperature in Celsius to Kelvin.

T = 273 + °C

T = 273 + 159

T = 432 Kelvin

To find the pressure of the gas, we would use the ideal gas law;

PV = nRT

Where;

  • P is the pressure.
  • V is the volume.
  • n is the number of moles of substance.
  • R is the ideal gas constant.
  • T is the temperature.

Making P the subject of formula, we have;

P = \frac {nRT}{V}

Substituting into the formula, we have;

P = \frac {0.467*0.08206*432}{0.245}

P = \frac {16.5551}{0.245}

<em>Pressure, P = 67.57 atm</em>

4 0
2 years ago
Mr. Swerdlow wrote a chemical equation on the board and asked his class what should be changed to make it correct. He wrote:
Misha Larkins [42]

Answer is: 3. Water and carbon dioxide should both be moved to the products side, and glucose and oxygen should be moved to the reactants side.

Balanced chemical reaction for cellular respiration (convert biochemical energy):

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy, or:

glucose + oxygen → carbon dioxide + water + energy.

This reaction is exothermic (energy is released).

6 0
3 years ago
Read 2 more answers
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