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ahrayia [7]
2 years ago
14

Atmospheric pressure is 1.00 atm, but air is only composed of 21.0% (by moles) oxygen. thus, the partial pressure of oxygen in a

ir is less than 1.00 atm. what is the millimolar concentration of dissolved oxygen for a lake or stream under the partial pressure of oxygen and a temperature of 20 ∘c?
Chemistry
1 answer:
Scilla [17]2 years ago
6 0

Answer:

8.74 millimolar.

Explanation:

  • The partial pressure of oxygen = (21.0 / 100) (1.0 atm) = 0.21 atm.
  • Using the ideal gas law: PV = nRT,
  • Where, P is the pressure in atm <em>(P = 0.21 atm)</em>, V is the volume in L, n is the number of moles, R is the general gas constant <em>(R = 0.082 l.atm/mo.K)</em>, and T is the temperature in K <em>(T = 20 °C + 273 = 293 K)</em>.
  • We can get the concentration in molar (n/V), The number of moles per 1.0 L of the solvent.
  • The concentration of oxygen in molar (n/V) = P/RT = (0.21 atm) / (0.082 L.atm/mol.K) (293 K) = 8.74 x 10³⁻ Molar = 8.74 millimolar.
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Consider a process in which the entropy of a system increases by 125 J K−1 and the entropy of the surroundings decreases by 125
expeople1 [14]

Answer : The process is not spontaneous.

Explanation :

As, we know that:

Change in entropy = Change in entropy of system + Change in entropy of surrounding

As we are given in question, the entropy of surroundings decrease by the same amount as the entropy of the system increases.

For the given reaction to be spontaneous, the total change in entropy should be positive.

Given :

Entropy change of system = +125J/K

Entropy change of surroundings = -125J/K

Total change in entropy = Entropy change of system + Entropy change of surroundings

Total change in entropy = 125 J/K + (-125 J/K)

Total change in entropy = 0

The process is at equilibrium because the entropy change is equal to zero. So, the process is not spontaneous.

4 0
2 years ago
The combustion of propane occurs when propane interacts with oxygen gas to produce water and carbon dioxide in the following rea
gtnhenbr [62]

Answer:

  • 20 atm

Explanation:

<u>1) Data:</u>

a) n = 2 moles

b) T = 373 K

c) V = 2.5 liter

d) P = ?

<u>2) Chemical principles and formula</u>

You need to calculate the pressure of the propane gas in the mixture before reacting. So, you can apply the partial pressure principle which states that each gas exerts a pressure as if it occupies the entire volume.

Thus, you just have to use the ideal gas equation: PV = nRT

<u>3) Solution:</u>

  • PV = nRT ⇒ P = nRT / V

P = 2 mol × 0.08206 atm-liter /K-mol × 373K / 2.5 liter = 24.5 atm

Since the number of moles are reported with one significant figure, you must round your answer to one significant figure, and that is 20 atm (20 is closer to 24.5 than to 30).

5 0
2 years ago
A line in the Brackett series of hydrogen has a wavelength of 1945 nm. From what state did the electron originate?
fiasKO [112]
Rydberg Eqn is given as:
 1/λ = R [1/n1^2 - 1/n2^2] 
<span>Where λ is the wavelength of the light; 2626 nm = 2.626×10^-6 m </span>
<span>R is the Rydberg constant: R = 1.09737×10^7 m-1 </span>
<span>From Brackett series n1 = 4 </span>
<span>Hence 1/(2.626×10^-6 ) = 1.09737× 10^7 [1/4^2 – 1/n2^2] </span>
<span>Some rearranging and collecting up terms: </span>
<span>1 = (2.626×10^-6)×(1.09737× 10^7)[1/16 -1/n2^2] </span>
<span>1= 28.82[1/16 – 1/n2^2] </span>
<span>28.82/n^2 = 1.8011 – 1 = 0.8011 </span>
<span>n^2 = 28.82/0.8011 = 35.98 </span>
<span>n = √(35.98) = 6</span>
4 0
2 years ago
Read 2 more answers
Write the formulas for the following ionic compounds: (a) copper bromide (containing the Cu+ ion), (b) manganese oxide (containi
ivann1987 [24]

Answer:The formulas of ionic compounds are:

a)CuBr

b)Mn_2O_3

c)Hg_2I_2

d)Mg_3(PO_4)_2

Explanation:

Formulas for the an ionic compounds is determine by:

Criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.

(a) Copper bromide :Given that it contains Cu^+ ion.

Cu^++Br^-\rightarrow CuBr

(b) Manganese oxide : Given that it contains Mn^{3+} ion.

Mn^{3+}+O^{2-}\rightarrow Mn_2O_3

(c)Mercury iodide :Given that it contains Hg_2^{2+}

Hg_2^{2+}+I^-\rightarrow Hg_2I_2

(d) Magnesium phosphate :Given that it contains PO_4^{3-}

Mg^{2+}+PO_4^{3-}\rightarrow Mg_3(PO_4)_2

4 0
2 years ago
Write the equations that represent the first and second ionization steps for hydroselenic acid (H2Se) in water. (Use H3O+ instea
Otrada [13]

Answer:

The equations are

1) H_{2}Se+H_{2}O--> H_{3}O^{+}+HSe^{-}

2) HSe^{-} +H_{2}O--> H_{3}O^{+}+Se^{-2}

Explanation:

There are two ionization steps in the dissociation of hydroselenic acid.

In first dissociation the H₂Se loses one proton and forms hydrogen selenide ion as shown below:

H_{2}Se+H_{2}O--> H_{3}O^{+}+HSe^{-}

The next step is again removal of a proton from the base formed above.

HSe^{-} +H_{2}O--> H_{3}O^{+}+Se^{-2}

4 0
2 years ago
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