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3 years ago

Why was Bohr's atomic model replaced by the

Chemistry

1 answer:

liubo4ka [24]3 years ago

6 0

answer: c- new knowledge showed that the exact location of electrons can not be known.

Explanation: i just did it ;)

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Which best describes a molecule?

lesantik [10]

I think it is the third statement
‘A unit is made up of two or more atoms’

3 0

4 years ago

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An endergonic reaction with a Δh and Δs can be changed into an exergonic reaction.

zheka24 [161]

Full question:

This question is incomplete, here it is completed:

An endergonic reaction with a ______ ∆H and a ______ ∆S can be changed into an exergonic reaction by decreasing the temperature.

Option A: negative, positive

Option B: negative, negative

Option C: positive, positive

Option D: positive, negative

Answer:

Option B: negative, negative

Explanation:

The change in free energy (ΔG) of a system for a constant-temperature process is

ΔG = ΔH - TΔS

free energy is the energy available to do work. Thus, if a particular reaction is accompanied by a release of usable energy (that is, ΔG is negative), it is said to be exergonic. On the other hand, if a reaction consumes energy (that is, ΔG is positive), it is said to be endergonic.

Looking at the equation, we can see that if ΔH is negative and ΔS is negative, then ΔG will be negative only when TΔS is smaller in magnitude than ΔH. This condition is met when T is small.

ΔG = ΔH - TΔS

- -

This means that the reaction proceeds spontaneously at low temperatures. At high temperatures, the reverse reaction becomes spontaneous. An example of that would be the following reaction:

NH₃(g) + HCl(g) → NH₄Cl(s)

4 0

3 years ago

Water has a boiling point of 100.0°C and a Kb of 0.512°C/m. What is the boiling

Reil [10]

Answer:

The boiling point of a 8.5 m solution of Mg3(PO4)2 in water is 394.91 K.

Explanation:

The formula for molal boiling Point elevation is :

$\Delta T_{b} = iK_{b}m$

$\Delta T_{b}$ = elevation in boiling Point

$K_{b}$ = Boiling point constant( ebullioscopic constant)

m = molality of the solution

i = Van't Hoff Factor

Van't Hoff Factor = It takes into accounts,The abnormal values of Temperature change due to association and dissociation .

In solution Mg3(PO4)2 dissociates as follow :

$Mg_{3}(PO_{4})_{2}\rightarrow 3Mg^{2+} + 2 PO_{4}^{3-}$

Total ions after dissociation in solution :

= 3 ions of Mg + 2 ions of phosphate

Total ions = 5

i = Van't Hoff Factor = 5

m = 8.5 m

$K_{b}$ = 0.512 °C/m

Insert the values and calculate temperature change:

$\Delta T_{b} = iK_{b}m$

$\Delta T_{b} = 5\times 0.512\times 8.5$

$\Delta T_{b} = 21.76 K$

Boiling point of pure water = 100°C = 273.15 +100 = 373.15 K

$\Delta T_{b} = T_{b} - T_{b}_{pure}$

$T_{b}_{pure}$ = 373.15 K[/tex]

21.76 = T - 373.15

T = 373.15 + 21.76

T =394.91 K

8 0

3 years ago

True or False: Photosynthesis can happen anytime, regardless of the amount of reactants present or the presence of sunlight.

Arisa [49]

The answer is false .

3 0

3 years ago

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Gasoline and motor oil are chemically similar. They are both mixtures of nonpolar hydrocarbons

Softa [21]

Answer:

motor oil

Explanation:

According to Oxford dictionary, viscosity refers to ''a quantity expressing the magnitude of internal friction in a fluid, as measured by the force per unit area resisting uniform flow.''

The higher the molecular weight of a substance, the greater its viscosity. This is because, the long chains in the viscous substance become entangled thereby increasing the internal friction in the liquid.

Motor oil is a heavier hydrocarbon than gasoline hence it is more viscous than gasoline.

5 0

3 years ago

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