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2 years ago

How many grams are in 9.05 x 1023 atoms of silicon?

Chemistry

1 answer:

Sergeu [11.5K]2 years ago

6 0

Explanation:

Number of moles(n)=Number of atoms(N)/Avogadro's constant.

Avogadro's constant=6.02×10²³

so we have

n=9.05×10²³/6.02×10²³

n=1.0503moles.

n=mass/molar mass

1.0503=mass/28

mass=1.0503×28

mass=29.4084g

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Hydrophobic compounds dissolve in

Anastaziya [24]

Hydrophobic molecules tend to be nonpolar molecules that group together to form micelles rather than be exposed to water. Hydrophobic molecules typically dissolve in nonpolar solvents (e.g., organic solvents).

4 0

3 years ago

Translation: Explain the importance of energy levels,

tigry1 [53]

Answer: Formation of a stable Duplet or Octet structure

Explanation:

Energy levels refers to the definite amount of energies that electrons can have when occupying specific orbitals.

Examples are:

Level 1 as in 1s

Level 2 as in 2s, 2p

Level 3 as in 3s 3p 3d

Level 4 as in 4s 4p 4d 4f

Level 5 as in 5s .......

Level 6 as in 6s .........

Electrons can be excited to higher energy levels by absorbing energy from the surroundings during chemical reactions and so forming chemical bonds like ionic, covalent etc.

A perfect example is Sodium (Na) and Chlorine (Cl) in Sodium chloride (NaCl)

Sodium has atomic number of 11, so energy level is 1s2, 2s2 2p6, 3s1

Chlorine has atomic number of 17, so energy level is 1s2, 2s2 2p6, 3s2 3p5

You will notice that the both Na and Cl, has electrons in the energy level 3. Then, the bond formed must be one that lead to the formation of a OCTET structure: as in Na gives off its 3s1 electron TO Cl.

Thus, Cl now becomes 1s2, 2s2 2p6, 3s2 3p6 - an OCTET STRUCTURE (with completely filled outershell and full energy level 3) in NACl.

So, a duplet or Octet structure is the answer

8 0

3 years ago

What is the kinetic energy of the emitted electrons when cesium is exposed to UV rays of frequency 1.0×1015Hz?

RideAnS [48]

The kinetic energy of the emitted electrons of cesium when it is exposed to UV rays of frequency $1.0 \times {10^{15}}\;{\text{Hz}}$ is $\boxed{6.63 \times {{10}^{ - 19}}\;{\text{J}}}$

Further Explanation:

Photoelectric effect:

When light is made to fall on any substance, electrons are emitted from it. This is known as the photoelectric effect and the emitted electrons are called photoelectrons. The electrons are emitted because of the transference of energy from light to the electrons.

Cesium is a member of the alkali metal group so it is highly reactive and shows photoelectric effect to the maximum extent. It can remove its electron so easily because of its atomic size. Due to large atomic size of cesium, its outermost electrons are held very less tightly to the nucleus and therefore removed easily.

According to the Planck-Einstein equation, the energy is proportional to the frequency and is expressed as follows:

${\mathbf{E=h\nu }}$ ......(1)

Here,

${\text{E}}$ is the energy.

$h$ is the Plank’s constant.

$\nu$ is the frequency.

The frequency of UV rays is $1.0 \times {10^{15}}\;{\text{Hz}}$ or $1.0 \times {10^{15}}\;{{\text{s}}^{ - 1}}$

The value of Planck’s constant is $6.626 \times {10^{ - 34}}\;{\text{J}}\cdot{\text{s}}$ .

Substitute these values in equation (1)

$\begin{aligned}{\text{E}}&=\left( {6.626 \times {{10}^{ - 34}}\;{\text{J}}\cdot{\text{s}}}\right)\left( {1.0 \times {{10}^{15}}\;{{\text{s}}^{ - 1}}}\right)\\&=6.63\times {10^{ - 19}}\;{\text{J}}\\\end{aligned}$

But when electrons are ejected out from the surface of the substance, all of its energy is considered as kinetic energy.

So the kinetic energy of the electrons is ${\mathbf{6}}{\mathbf{.63 \times 1}}{{\mathbf{0}}^{{\mathbf{ - 19}}}}\;{\mathbf{J}}$ .

Learn more:

1. Statement about subatomic particle: brainly.com/question/3176193

2. The energy of a photon in light: brainly.com/question/7590814

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Structure of the atom

Keywords: kinetic energy, frequency, energy, photoelectric effect, Planck's constant, light, electrons, photoelectrons, proportional, transference, reactive, cesium.

7 0

3 years ago

Read 2 more answers

If the following weights have masses of 2, 4, 6 and 8 kg,

Marrrta [24]

Answer:

8 kg mass

Explanation:

As we can see in the image the weight of mass 8 kgs has a large surface area as compared to the surface area of other masses. In general, it has been observed that a wide surface area has more surface particle for heat conduction. Hence, the rate of heat transfer is directly proportional to the surface area of heat conducting surface. Thus, the larger the surface area, the faster is the rate of heat conduction.

Hence, weight of mass 8Kg wil transfer heat a fast rate.

6 0

3 years ago

What is the mass of 0. 513 mol Al2O3? Give your answer to the correct number of significant figures. (Molar mass of Al2O3 = 102.

Margarita [4]

The mass of a 0.513 mol of Al2O3 is 52.33g.

HOW TO CALCULATE MASS:

The mass of a substance can be calculated by multiplying the molar mass of the substance by its number of moles. That is;

mass of Al2O3 = no. of moles of Al2O3 × molar mass of Al2O3

According to this question, there are 0.513 moles of Al2O3.

Mass of Al2O3 = 0.513 × 102

Mass of Al2O3 = 52.33g

Therefore, the mass of a 0.513 mol of Al2O3 is 52.33g.

Learn more about mass calculations at: brainly.com/question/8101390?referrer=searchResults

7 0

2 years ago