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sergejj [24]
3 years ago
7

For the hexagonal close-packed crystal: (12 points) a. How many atoms are associated with the unit cell? b. What is the coordina

tion number? c. What is the atomic packing factor?
Chemistry
1 answer:
melomori [17]3 years ago
3 0

Answer :

(a) Total number of atoms in the cell = 6

(b) The coordination number of HCP is, 12

(c) The atomic packing factor is, 74.0 %

Explanation :

<u>Hexagonal close-packed structure (HCP) :</u>

Crystal structure : The manner in which the atoms or ions are spatially arranged.

(a) The HCP unit cell consist of three primitive unit cells in a hexagonal prism. That means, 3 atoms are in the middle layer and 12 atoms are at top and bottom layers and 2 face atoms.

So, the total number of atoms in the cell = 3 + (1/2)×2 + (1/6)×6 × 2 = 6

(b) Coordination number : It is defined as any constituent particle in a crystal is the number of its nearest neighbours.

The coordination number of HCP is, 12

(c) Packing fraction or factor : It is defined as the percentage of the total space filled by the particles.

\text{Packing factor}=\frac{n\times V_{atom}}{V_{cell}}\times 100

\text{Packing factor}=\frac{6\times (\frac{4}{3}\pi r^3)}{24\sqrt{2}r^3}\times 100

\text{Packing factor}=74.0\%

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What's the balanced equation for cellular respiration?
Alik [6]
<span>Correct answer is:

C_{6}H_{12}O_6+6O_{2}\Rightarrow 6CO_{2}+6H_{2}O+energy

But how to get there?

Let's start with simple explanation of what exactly is cellular respiration. 

Cellular respiration is a multistage biochemical oxidation process of organic substances when prime product is energy (ATP - adenosine triphosphate) and other are released waste products. Cellular respiration takes place even if other metabolic processes are stopped, but cellular respiration may differ in particular organism groups.Some reactions during whole process of cellular respiration are similar in all types of living organisms.

Cellular respiration is prime indication of declining living processes.Only viruses which are on the edge of living organism and chemical particle are not performing cellular respiration.But to the point :P

In cellular respiration all substrates which are in the cell might be organic, but mostly we are using sugar oxidation - glucose in the presence of oxygen. Chemical formula of sugar looks like this:

C_{6}H_{12}O_6

Oxygen is just

O_2

so for now we have just part of the equation:

C_{6}H_{12}O_6+O_{2}\Rightarrow

But what would be on the right hand side?

It's quite simple, remember equation of full combustion? If we want to burn something we need oxygen like in the equation, so the product of this equation would be carbon dioxide, water and of course energy (ATP).Carbon dioxide formula looks like this:

CO_{2}

As a reminder water formula:

H_{2}O

Full formula would look like that:

C_{6}H_{12}O_6+O_{2}\Rightarrow\ CO_{2}+H_{2}O+energy

But still as you see this equation is unbalanced, after balancing it would like that:

C_{6}H_{12}O_6+6O_{2}\Rightarrow 6CO_{2}+6H_{2}O+energy

At the end I would like to explain one more thing. Energy which has been released during this process is part of high-energy connection which might be used to perform chemical reactions in the cell or to move organism for example in muscles. We need to remember that production of ATP is not happening with 100% efficiency and part of this energy is released as heat.</span>
5 0
3 years ago
If you have an aqueous solution that contains 1.5 moles of hcl, how many moles of ions are in the solution? (a) 1.0, (b) 1.5, (c
Darya [45]

If you have an aqueous solution that contains 1.5 moles of HCl, the number of moles of ions in the solution is 3.0 moles.

<h2>Further Explanation </h2><h3>Strong acids  </h3>
  • Strong acids are types of acids that undergo complete dissociation to form ions when dissolved in water.
  • Examples of such acids are, HCl, H2SO4 and HNO3
  • Dissociation of HCl

HCl + H₂O ⇔ H₃O⁺ + OH⁻

<h3>Weak acids  </h3>
  • Weak acids are types of acids that undergo incomplete dissociation to form ions when dissolved in water.
  • Examples of such acids are acetic acids and formic acids.
  • Dissociation of  acetic acid

H₃COOH ⇔ CH₃COO⁻ + H⁺; CH₃COO⁻ is a conjugate base of acetic acid.

<h3>In this case;</h3>
  • HCl which is a strong acid that ionizes completely according to the equation;

HCl + H₂O ⇔ H₃O⁺ + OH⁻

  • From the equation, 1 mole of HCl produces 1 mole of H₃O⁺ ions and 1 mole of OH⁻ ions.

Therefore;

1.5 moles of HCl will produce;

= 1.5 moles of H₃O⁺ ions and 1.5 moles of OH⁻ ions.

This gives a total number ions of;

= 1.5 + 1.5

= 3 moles of ions

Keywords:  Strong acid, weak acid, ions, ionization

<h3>Learn more about: </h3>
  • Strong acid: brainly.com/question/3239966
  • Weak acid; brainly.com/question/3239966
  • Ionization of acids and bases: brainly.com/question/11844503

Level: High school

Subject: Chemistry

Topic: Salts, Acids and Bases

6 0
3 years ago
Read 2 more answers
M. element<br>cenabrecht<br>0.5 mele of an​
drek231 [11]

Answer:

Number of moles (n)=

molecular weight

weight

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lutik1710 [3]

Answer:

HCI(aq)+CH3COONa(s) ----> CH3COOH(aq)+NaCl(s)

NaOH(aq)+CH3COOH(aq) ----> CH3COONa(s)+H2O(l)

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A buffer may be an aqueous solution of a weak acid and its conjugate base or a weak base and its conjugate acid.

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HCI(aq)+CH3COONa(s) ----> CH3COOH(aq)+NaCl(s)

NaOH(aq)+CH3COOH(aq) ----> CH3COONa(s)+H2O(l)

5 0
3 years ago
What determines a molecules VSEPR shape?
frosja888 [35]
Using the VSEPR theory, the electron bond pairs and lone pairs on the center atom will help us predict the shape of a molecule. The shape of a molecule is determined by the location of the nuclei and its electrons. The electrons and the nuclei settle into positions that minimize repulsion and maximize attraction.
3 0
3 years ago
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