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Which determines how atoms combine to form molecules?

arlik [135]

Will be letter E cause all of them can combine molecule

7 0

3 years ago

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

#1: How are the elements arranged in the modern periodic table?

Alekssandra [29.7K]

1- The correct answer is C :

the elements arranged in the modern periodic table by increasing atomic number.

The explanation:

-The elements in the periodic table are arranged to increase the atomic number. All of these elements display several other trends and we can use the periodic law and table formation to predict their chemical, physical, and atomic properties.

2- The correct answer is C:

strontium, magnesium, calcium, beryllium are the elements which have similar properties.

The explanation:

-strontium, magnesium, calcium, beryllium, these belong to the alkaline earth metal group.

Because the outer electron structure in all of these elements is similar, they all have somewhat similar chemical and physical properties .

3- The correct answer is A :

Potassium

The explanation:

-The elements potassium and sodium have similar chemical properties because they have the same number of valence electrons and form +1 ions.

4- The correct answer is D

The explanation:

Mendeleev didn't include helium, neon, and argon in his periodic table because these elements had not yet been discovered.

5- The correct answer is B:

The periodic law describes trends seen across periods within the periodic table.

The explanation:

When the chemical elements are arranged, there is a pattern called the “periodic law” in their properties, in which elements in the same column (group) have similar properties

4 0

3 years ago

Read 2 more answers

The solid compound, K2SO4, contains?

givi [52]

The solid compound, K2SO4 contains a cation called K+ and an anion called SO42-. In this case, there are 2 atoms of potassium, 1 atom of sulfur and 4 moles of oxygen. The compound also contains ionic bonds because of the composing non-metals and metal.

3 0

3 years ago

Why do oxygen and hydrogen can be kept underwater

Scrat [10]

The reason we cannot breath liquid water is because the oxygen used to make the water is bound to two hydrogen atoms and we cannot breath the resulting liquid

8 0

3 years ago