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3 years ago

A element or compound which occurs naturally in the earth

1 answer:

5 0

An element or compound which occurs naturally in the earth is a mineral. Minerals are substances formed naturally in the Earth.They have a definite chemical composition and structure. For example, the minerals gold or diamonds you’d find by mining or panning for gold since they are found naturally in the Earth.

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Which of the following best defines the internal energy of a system?

Anarel [89]

<span>In thermodynamics, the internal energy of a thermodynamic system, or a body with well-defined boundaries, denoted by U, or sometimes E, is the total of the kinetic energy due to the motion of molecules (translational, rotational, vibrational) and the potential energy associated with the vibrational and electric energy of atoms within molecules or crystals. It includes the energy in all the chemical bonds, and the energy of the free, conduction electrons in metals.</span>

7 0

3 years ago

“Least molecular motion, lowest kinetic energy, strongest forces of attention, most dense packaging of molecules”. Which state o

SashulF [63]

<h2><em>Solid. Because molecules densely packed it has a high resistance to flow thereby lower kinetic energy. </em></h2>

8 0

3 years ago

Use bond energies to calculate the enthalpy of reaction for the combustion of ethane. Average bond energies in kJ/mol C-C 347, C

ivanzaharov [21]

The enthalpy of reaction for the combustion of ethane 2CH₃CH₃ + 7O₂ → 4CO₂ + 6H₂O calculated from the average bond energies of the compounds is -2860 kJ/mol.

The reaction is:

2CH₃CH₃ + 7O₂ → 4CO₂ + 6H₂O (1)

The enthalpy of reaction (1) is given by:

$\Delta H = \Delta H_{r} - \Delta H_{p}$ (2)

Where:

r: is for reactants

p: is for products

The bonds of the compounds of reaction (1) are:

2CH₃CH₃: 2 moles of 6 C-H bonds + 2 moles of 1 C-C bond

7O₂: 7 moles of 1 O=O bond

4CO₂: 4 moles of 2 C=O bonds

6H₂O: 6 moles of 2 H-O bonds

Hence, the enthalpy of reaction (1) is (eq 2):

$\Delta H = \Delta H_{r} - \Delta H_{p}$

$\Delta H = 2*\Delta H_{CH_{3}CH_{3}} + 7\Delta H_{O_{2}} - (4*\Delta H_{CO_{2}} + 6*\Delta H_{H_{2}O})$

$\Delta H = 2*(6*\Delta H_{C-H} + \Delta H_{C-C}) + 7\Delta H_{O=O} - (4*2*\Delta H_{C=O} + 6*2*\Delta H_{H-O})$

$\Delta H = [2*(6*413 + 347) + 7*498 - (4*2*799 + 6*2*467)] kJ/mol$

$\Delta H = -2860 kJ/mol$

Therefore, the enthalpy of reaction for the combustion of ethane is -2860 kJ/mol.

I hope it helps you!

7 0

2 years ago

What is the most common way atoms combine

Semenov [28]

Atoms combine<span> by forming chemical bonds</span>

4 0

3 years ago

A chemical reaction that has a positive δg is correctly described as

Charra [1.4K]

Answer:

Endergonic reaction or nonspontaneous reaction.

Explanation:

Gibbs free energy is a state function that determines the spontaneity or feasibility of the given reversible chemical reaction, at fixed pressure and temperature. It is given by the equation:

ΔG = ΔH - TΔS

Here, ΔG - change in Gibbs free energy

ΔH- The change in enthalpy of reaction

ΔS - The change in entropy

T- Temperature

When the <u>change in the Gibbs free energy for a given reaction is positive</u> (ΔG > 0), then that chemical reaction is known as an endergonic reaction or nonspontaneous reaction.

4 0

3 years ago