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3 years ago

What does the kinetic theory say about the kinetic energy present in solids

1 answer:

4 0

Answer: The kinetic energy of solids is limited to vibrational energies..the particles are tightly bound in their crystalline structure and can only bend, flex, and vibrate about relatively fixed position. When vibrational energies exceed the strength of the force holding the particles together, the crystal structure collapses and we say the material melted. The particles can now have, in addition to its vibrational energies, rotational energy. Chunks of the collapsed crystal can, like a ball floating in water, rotate without showing much translational energy. Generally, we associate solids with vibrational kinetic energy, liquids with rotational kinetic energy, and gases with translational kinetic energy. Actually though, liquids have both vibrational and rotational energies, and gases have all three.

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How many formula units make up 24.2 g of magnesium chloride (MgCl2)? Help!!

NNADVOKAT [17]

Answer:

Approximately $1.53 \times 10^{23}$ formula units ( $0.254\; \rm mol$ ).

Explanation:

Refer to a modern periodic table for the relative atomic mass of magnesium ( $\rm Mg$ ) and chlorine ( $\rm Cl$ ):

$\rm Mg$ : $24.305$ .
$\rm Cl$ : $35.45$ .

In other words, the mass of $1\; \rm mol$ of $\rm Mg$ atoms would be (approximately) $24.305\; \rm g$ .

Likewise, the mass of $1\; \rm mol$ of $\rm Cl$ atoms would be approximately $35.45\; \rm g$ .

One formula unit of the ionic compound $\rm MgCl_{2}$ includes exactly as many atoms as there are in the given formula. The formula mass of a compound is the mass of $1\; \rm mol$ of the formula units of this compound.

The formula $\rm MgCl_{2}$ includes one $\rm Mg$ atom and two $\rm Cl$ atoms.

Hence, every formula unit of $\rm MgCl_{2} \!$ would include the same number of atoms: one $\rm Mg\!$ atom and two $\rm Cl\!$ atoms. There would be $1\; \rm mol$ of $\rm Mg$ atoms and $2\; \rm mol$ of $\rm Cl$ atoms in $1\; \rm mol\!$ of $\rm MgCl_{2}$ formula units.

Thus, the mass of $1\; \rm mol\!$ of $\rm MgCl_{2}$ formula units would be equal to the mass of $1\; \rm mol$ of $\rm Mg$ atoms plus the mass of $2\; \rm mol$ of $\rm Cl$ atoms. (The mass of $1\; \rm mol\!\!$ of each atom could be found from the relative atomic mass of each element.)

$\begin{aligned}& M({\rm MgCl_{2}}) \\ =\; & 24.305\; {\rm g \cdot mol^{-1}} + 2\times {\rm 35.45 \; \rm g \cdot mol^{-1}} \\ =\; & 95.205\; \rm g \cdot mol^{-1}\end{aligned}$ .

In other words, the formula mass of $\rm MgCl_{2}$ is $95.205\; \rm g \cdot mol^{-1}$ .

Therefore, the number of formula units in $m = 24.2\; \rm g$ of $\rm MgCl_{2}$ would be:

$\begin{aligned}n &= \frac{m({\rm MgCl_{2}})}{M({\rm MgCl_{2}})} \\ &= \frac{24.2\; \rm g}{95.205\; \rm g\cdot mol^{-1}} \\ & \approx 0.254\; \rm mol\end{aligned}$ .

Multiple $n$ by Avogadro's Number $N_{A} \approx 6.022 \times 10^{23}\; \rm mol^{-1}$ to estimate the number of formula units in $0.254\; \rm mol$ :

$\begin{aligned}N &= n \cdot N_{A} \\ &\approx 0.254\; \rm mol \times 6.022 \times 10^{23}\; \rm mol^{-1} \\ &\approx 1.53\times 10^{23}\end{aligned}$ .

6 0

2 years ago

A scientist notices that a lump of niobium is warm to the touch and wonders if nuclear reactions are taking place in the metal.

Sedaia [141]

Of the answers listed option B looks like the most complete. Ie "Check for the presence of alpha, beta, and gamma particles." the significant presence of these particles is a specific indicator of radioactive decay, i.e: unstable atoms spontaneously undergoing a nuclear reaction.

6 0

3 years ago

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Electrons in atoms exist in particular energy level. A ___ must be emitted or absorbed to move between energy levels.

svetlana [45]

Answer:

Photon of light

Explanation:

According to Bohr's model of the atom, electrons in atoms are found in specific energy levels. These energy levels are called stationary states, an electrons does not radiate energy when it occupies any of these stationary states.

However, an electron may absorb energy and move from one energy level or stationary state to another. The energy difference between the two energy levels must correspond to the energy of the photon of light absorbed in order to make the transition possible.

Since electrons are generally unstable in excited states, the electron quickly jumps back to ground states and emits the excess energy absorbed. The frequency or wavelength of the emitted photon can now be measured and used to characterize the transition. This is the principle behind many spectrometric and spectrophotometric methods.

8 0

3 years ago

Plz help ya' girl out! Label the parts of whatever that is Plz giving brainliest!

Burka [1]

Answer:

BRAINLIEST PLEASE!!!

A = Smooth Endoplasmic Reticulum

B = Vacuole

C = Mitochondria (Plural)

D = Nucleolus

E = Cell Wall

Explanation:

This is obviously a plant cell. Animal cells do not have cell walls(E), and most animal cells will not have a vacuole(B). Smooth Endoplasmic Reticulum: This produces protiens (contains ribosomes) but when looked through a microscope, will appear to be smooth. The vacuole(B) is like a storage for the plant cell, and it helps support the plant cell. This is the reason why plants “droop” when you don’t water them for a long time. Mitochondia (Plural) processes nutrients for the cell. The nucleolus(D) covers the nucleus. It’s main function is to process RNA and combine it with proteins. The cell wall(E) helps support and protect the cell.

4 0

2 years ago

Which of these is an example of a physical change?

Luda [366]

The answer is D) wood decaying

4 0

3 years ago

Read 2 more answers