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4 years ago

How do fossils provide evidence of continental drift?

1 answer:

8 0

If the fossils from one shore are also on a different shore on a different continent, they probably didn't migrate from shore to shore. sorry that I didn't shorten it as much as I could.

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A gas stream containing n-hexane in nitrogen with a relative saturation of 0.58 (as a fraction, multiply by 100% if you prefer %

kondor19780726 [428]

This problem is describing a gas mixture whose mole fraction of hexane in nitrogen is 0.58 and which is being fed to a condenser at 75 °C and 3.0 atm, obtaining a product at 3.0 atm and 20 °C, so that the removed heat from the system is required.

In this case, it is recommended to write the enthalpy for each substance as follows:

$H_{C-6}=y_{C-6}C_v(T_b-Ti)+\Delta _vH+C_v(T_f-Tb)\\\\H_{N_2}=y_{N_2}C_v(T_f-Ti)$

Whereas the specific heat of liquid and gaseous n-hexane are about 200 J/(mol*K) and 160 J/(mol*K) respectively, its condensation enthalpy is 31.5 kJ/mol, boiling point is 69 °C and the specific heat of gaseous nitrogen is about 29.1 J/(mol*K) according to the NIST data tables and $y_{C-6}$ and $y_{N_2}$ are the mole fractions in the gaseous mixture. Next, we proceed to the calculation of both heat terms as shown below:

$H_{C-6}=0.58*200(69-75)+(-31500)+160(20-69)=-40036J/mol\\\\H_{N_2}=0.42*29.1(20-75)=-672.21J/mol$

It is seen that the heat released by the nitrogen is neglectable in comparison to n-hexanes, however, a rigorous calculation is being presented. Then, we add the previously calculated enthalpies to compute the amount of heat that is removed by the condenser:

$Q=-40036+(-672.21)=-40708.21J$

Finally we convert this result to kJ:

$Q=-40708.21J*\frac{1kJ}{1000J}\\\\Q=-40.7kJ$

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6 0

2 years ago

An aqueous solution of sodium thiosulfate releases heat when it crystallizes. What would happen when sodium thiosulfate crystals

rusak2 [61]

Answer:

An excellent experiment is to heat sodium thiosulfate in a water bath. The solid crystals will dissolve into the water in the hydrated crystals forming a supersaturated solution. ... Placing a small crystal in the supersaturated solution will cause the liquid to turn solid.

7 0

3 years ago

A gas at 29.4 kPa is cooled from a temperature of 75°C to a temperature of 25°C at constant volume. What is the new pressure of

kirill115 [55]

<span>To solve this we assume that the gas inside the balloon is an ideal </span>gas. Then, we can use the ideal gas equation which is expressed as PV = nRT. At a constant volume pressure and number of moles of the gas the ratio of T and P is equal to some constant. At another set of condition, the constant is still the same. Calculations are as follows:

T1/P1 = T2/P2

P2 = T2 x P1 / T1

P2 = 25 x 29.4 / 75

P2 = 9.8 kPa

7 0

3 years ago

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How are we made from star debris? What does this mean? Explain

4vir4ik [10]

Answer:

How star stuff got to Earth

When it has exhausted its supply of hydrogen, it can die in a violent explostion, called a nova. The explosion of a massive star, called a supernova, can be billions of times as bright as the Sun , according to "Supernova," (World Book, Inc., 2005). Such a stellar explosion throws a large cloud of dust and gas into space, with the amount and composition of the material expelled varying depending on the type of supernova.

A supernova reaches its peak brightness a few days after it first occurred, during which time it may outshine an entire galaxy of stars. The dead star then continues to shine intensely for several weeks before gradually fading from view, according to "Supernova."

The material from a supernova eventually disperses throughout interstellar space. The oldest stars almost exclusively consisted of hydrogen and helium, with oxygen and the rest of the heavy elements in the universe later coming from supernova explosions, according to "Cosmic Collisions: The Hubble Atlas of Merging Galaxies," (Springer, 2009).

"It's a well-tested theory," Impey said. "We know that stars make heavy elements, and late in their lives, they eject gas into the medium between stars so it can be part of subsequent stars and planets (and people)."

Cosmic connections

So, all life on Earth and the atoms in our bodies were created in the furnace of now-long-dead stars, he said.

In 2002, music artist Moby released "We Are All Made of Stars," explaining during a press interview that his lyrics were inspired by quantum physics. "On a basic quantum level, all the matter in the universe is essentially made up of stardust," he said.

Explanation:

7 0

3 years ago

A sample of an ionic compound containing iron and chlorine is analyzed and found to have a molar mass of 126.8 g/mol. what is th

julsineya [31]

Answer is: <span>the charge of the iron in this compound is +2.
Atomic mass of iron is 55,8 g/mol.
Atomic mass of chlorine is 35,5 g/mol.
If compound is FeCl, molar mass would be 55,8 </span>g/mol + 35,5 g/mol = 91,3 g/mo, that is not correct.
If compound is FeCl₂, malar mass of compound would be:
55,8 g/mol + 2·35,5 g/mol = 126,8 g/mol, that is correct.
Oxaidation number of chlorine is -1.

5 0

3 years ago

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