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Svetllana [295]
3 years ago
9

What are three reasons why a population might change?

Chemistry
1 answer:
Tom [10]3 years ago
4 0
If people have children, If people die, and if there is a fire or volcanic eruption.

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At a certain temperature the vapor pressure of pure thiophene is measured to be . Suppose a solution is prepared by mixing of th
Lesechka [4]

Answer:

0.35 atm

Explanation:

It seems the question is incomplete. But an internet search shows me these values for the question:

" At a certain temperature the vapor pressure of pure thiophene (C₄H₄S) is measured to be 0.60 atm. Suppose a solution is prepared by mixing 137. g of thiophene and 111. g of heptane (C₇H₁₆). Calculate the partial pressure of thiophene vapor above this solution. Be sure your answer has the correct number of significant digits. Note for advanced students: you may assume the solution is ideal."

Keep in mind that if the values in your question are different, your answer will be different too. <em>However the methodology will remain the same.</em>

First we <u>calculate the moles of thiophene and heptane</u>, using their molar mass:

  • 137 g thiophene ÷ 84.14 g/mol = 1.63 moles thiophene
  • 111 g heptane ÷ 100 g/mol = 1.11 moles heptane

Total number of moles = 1.63 + 1.11 = 2.74 moles

The<u> mole fraction of thiophene</u> is:

  • 1.63 / 2.74 = 0.59

Finally, the <u>partial pressure of thiophene vapor is</u>:

Partial pressure = Mole Fraction * Vapor pressure of Pure Thiophene

  • Partial Pressure = 0.59 * 0.60 atm
  • Pp = 0.35 atm

3 0
3 years ago
3. What is the energy of a photon whose frequency is 5.2 x 1015 Hz? Use the equation: E = hxv
anzhelika [568]

Answer:

3. 3.45×10¯¹⁸ J.

4. 1.25×10¹⁵ Hz.

Explanation:

3. Determination of the energy of the photon.

Frequency (v) = 5.2×10¹⁵ Hz

Planck's constant (h) = 6.626×10¯³⁴ Js

Energy (E) =?

The energy of the photon can be obtained by using the following formula:

E = hv

E = 6.626×10¯³⁴ × 5.2×10¹⁵

E = 3.45×10¯¹⁸ J

Thus, the energy of the photon is 3.45×10¯¹⁸ J

4. Determination of the frequency of the radiation.

Wavelength (λ) = 2.4×10¯⁵ cm

Velocity (c) = 3×10⁸ m/s

Frequency (v) =?

Next, we shall convert 2.4×10¯⁵ cm to metre (m). This can be obtained as follow:

100 cm = 1 m

Therefore,

2.4×10¯⁵ cm = 2.4×10¯⁵ cm × 1 m /100 cm

2.4×10¯⁵ cm = 2.4×10¯⁷ m

Thus, 2.4×10¯⁵ cm is equivalent to 2.4×10¯⁷ m

Finally, we shall determine the frequency of the radiation by using the following formula as illustrated below:

Wavelength (λ) = 2.4×10¯⁷ m

Velocity (c) = 3×10⁸ m/s

Frequency (v) =?

v = c / λ

v = 3×10⁸ / 2.4×10¯⁷

v = 1.25×10¹⁵ Hz

Thus, the frequency of the radiation is 1.25×10¹⁵ Hz.

8 0
2 years ago
2. Why can we eliminate the claim you circled?
Luda [366]

Answer: theres no image or claim

7 0
3 years ago
Read 2 more answers
The activation energy for proline isomerization of a peptide depends on the identity of the preceding residue and obeys Arrheniu
MAVERICK [17]

Answer:

Activation energy of phenylalanine-proline peptide is 66 kJ/mol.

Explanation:

According to Arrhenius equation-     k=Ae^{\frac{-E_{a}}{RT}}    , where k is rate constant, A is pre-exponential factor, E_{a} is activation energy, R is gas constant and T is temperature in kelvin scale.

As A is identical for both peptide therefore-

                                   \frac{k_{ala-pro}}{k_{phe-pro}}=e^\frac{[E_{a}^{phe-pro}-E_{a}^{ala-pro}]}{RT}

Here \frac{k_{ala-pro}}{k_{phe-pro}}=\frac{0.05}{0.005} , T = 298 K , R = 8.314 J/(mol.K) and E_{a}^{ala-pro}=60kJ/mol

So, \frac{0.05}{0.005}=e^{\frac{[E_{a}^{phe-pro}-(60000J/mol)]}{8.314J.mol^{-1}.K^{-1}\times 298K}}

   \Rightarrow E_{a}^{phe-pro}=65705J/mol=66kJ/mol (rounded off to two significant digit)

So, activation energy of phenylalanine-proline peptide is 66 kJ/mol

7 0
3 years ago
__________are when the Sun, Earth, and moon align in a straight line, the tides are higher than normal high
IceJOKER [234]
An eclipse i’m pretty sure right? Lunar maybe?
4 0
2 years ago
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