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hammer [34]
3 years ago
11

One crystalline form of silica (SiO2) has a cubic unit cell, and from X-ray diffraction data it is known that the cell edge leng

th is 0.700 nm. If the measured density is 2.32 g/cm3, how many (a) Si4 and (b) O2- ions are there per unit cell
Chemistry
1 answer:
tigry1 [53]3 years ago
6 0

Answer:

There are 8Si atoms and 16 O atoms per unit cell

Explanation:

From the question we are told that:

Edge length l=0.700nm=>0.7*10^9nm

Density \rho=2.32g/cm^3

Generally the equation for Volume is mathematically given by

V=l^3

V=(0.7*10^9)m^3

V=3,43*10^-{22}cm

Where

Molar mass of  (SiO2) for one formula unit

M=28+32

M=60g/mol

Therefore

Density of Si per unit length is

\rho_{si}=\frac{9.96*10^{23}}{3.43*10^22}

\rho=0.29

Molar mass of  (SiO2) for one formula unit

M=28+32

M=60g/mol

Therefore

There are 8Si atoms and 16 O atoms per unit cell

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Which of these pairs indicates an incorrect coupling of reversible reactions?dehydration synthesis and hydrolysisanabolic and ca
Olegator [25]

Answer:

option C= hydrolysis and break down

Explanation:

All other three pairs are correct coupling of each others.

Option A= dehydration synthesis and hydrolysis

Dehydration synthesis:

In dehydration synthesis monomers combine through the covalent bonds and form large molecules. The large molecules are called polymers. The water as a byproduct also released when monomers joints together.

Hydrolysis:

In hydrolysis the polymers are break down into monomers by using water molecules. The catalysts are also required in this process.

Option B= Catabolic and Anabolic

Anabolic:

In this process smaller molecules combine to gather to form large complex molecules by using energy.

For example simple glucose molecules join together to form large disaccharides.

Catabolic:

It is the break down of large complex molecules to the smaller molecules.

For example during cellular respiration sugar molecules break down and generate energy.

Option D=  Break down and synthesis

The break down and synthesis are also reverse pair of each others. The  synthesis involve the formation of molecules form smaller component while the break down involve destruction of molecules into smaller units.

8 0
3 years ago
The concentration of a salt solution in terms of mass by mass percentage is 20% and the mass of the solution is 500g determine t
marin [14]
100 grams of solute would be present as 20% of 500 is 100
5 0
3 years ago
Classify the following as a solution, suspension or colloid
frosja888 [35]

Answer:

Solution - (a) Brine . Suspension - (c) sand and water, (g) chalk and water​ Colloid - (e) air,  (f) smoke , (d) soda , (b) milk

Explanation:

A solution is an homogeneous mixture of two or more compounds.

A suspension is a heterogeneous mixture of two or more compounds while a colloid is a homogeneous mixture of two or more compounds with suspended particles which do not settle.

So, under these definitions, the classifications are as follows-

Solution - (a) Brine .

Suspension - (c) sand and water, (g) chalk and water​

Colloid - (e) air,  (f) smoke , (d) soda , (b) milk

6 0
3 years ago
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prohojiy [21]

Answer:

A= carbon

B= iron

C= Brass

D= water

E= soil?

F= magnesium oxide

G= Steel

H=wine

7 0
3 years ago
Which of the following is NOT a way carbon dioxide returns to the atmosphere?
yawa3891 [41]

Answer:

emissions by factories is the answer

Explanation:

Factories produce air pollution which is polluted air, the other options

decay of organisms, photosynthesis (convert light energy into chemical energy - and returns CO2), and cellular respiration are all of the ways carbon dioxide returns to the atmosphere.

Hope this helped! Have a nice day, be safe and healthy :)

4 0
3 years ago
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