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LuckyWell [14K]
3 years ago
10

During which two processes does a substance release energy?

Chemistry
1 answer:
enyata [817]3 years ago
6 0

Answer:

Freezing and condensation

Explanation:

Because they are exothermic, they release energy

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Estimate the coordination number for the cations in each of these ceramic oxides and also the coordination numbers of the oxygen
Juli2301 [7.4K]

Answer:

CN cation, anion ] respectively are thus [6,4] , [2,3] ,[6,6] , [6,6] , [6,3] , [12,6,2] , [6], [6].

Explanation:

The coordination number CN is the number of ligand atoms bonded (coordinate bonds) directly to the central of the metal ion. It is not the same as the oxidation state of the metal ion or complex.

Coordination number – the number of anions surrounding the cation.

In solving for CN we need to understand Pauling's rules.

According to Linus Pauling, 1932

“Pauling’s rules” for crystal structures, makes assumptions for ionic bonding. It states that ionic structure is understood using electrostatic rules of attraction and repulsion.

Cations and anions surround each other to neutralize charge – and these one can rationalize crystal structure with coordination number.

Ratio of cationic/anionic radius

• The structure of D-Al2O3 results in coordination number of 6 and 4 for cation and anion respectively.

• The average oxygen coordination number in v-B2O3 is equal to the average cation coordination number × cation/anion ratio (2/3).

• Co-ordination number of Ca2+ ion is =6;

In CaO crystal, Ca2+ is a cation and O2- is an anion. Cationic (Ca2+) has radius 100 pm and anionic (O2-) has radius  145 pm.

Ratio of cationic/anionic radius is:

r⁺/r⁻ = 100 / 145

r⁺/r⁻ = 0.69

CaO will form FCC lattice.

Coordination number in FCC lattice is 6. Therefore CN of Ca2+ = 6.

For MgO:

r Mg2+/ r O2- = 86pm / 126 pm =0.683

The cordination number for the cation is 6. MgO with ions Mg+2 and O-2 will have a AX type stochiometry exhibiting the

crystal structure of sodium chloride.

For TiO2:

The CN of the titanium (IV) cation is 6, which is twice the CN of the oxide anion, which is 3.

This fits with the formula unit of TiO2, since there are twice as many O2− ions as Ti4+ ions.

Consequently the crystal structure of all ionic compounds reflects the formula unit.

For LaAlO3 a Cubic perovskites (ABX3)

In perovskite structures, B cations are coordinated by six X anions, while A

cations present CN = 12 (also coordinated by X anions). The X anions have CN = 2, being

coordinated by two A cations, since the distance A-O is about 40% larger than the B-O

bond distance. The correct ionic radii (rA, rB, rX), taken from one of Shannon’s work.

rA = 1.36 pm

rB = 0.535 pm

rX = 1.35 pm

Forsterite Mg2SiO4

We have mixed sites of Si4+ in tetrahedral site, Mg2+ in octahedral site, O atoms anions .

They all forms octahedral chains/strips. The CN is estimated to (6) octahedral, with an average ratio 0.414

Nickel Cobaltite Ni(Co2O4)3

bidentate ligand includes the Oxalate, three oxalate ligands form six-coordinate bonds around the Ni2+ ion.

Co-ordinate number of Nickel in [Ni(C2​O4​)3​] 4− is 3×2=6.

5 0
3 years ago
Review this reaction:H2SO4 + NaOH ?.What are the product(s)?Na2SO4H2ONa2SO4 and H2ONaH and SO4OHH3SO5
muminat

i think its MIDDLE FINGERS UP IN THE SKY AND AT THESE AHOLE MODERATORS

6 0
3 years ago
Read 2 more answers
Please help. thanks :)
sleet_krkn [62]

The correct answer would be equation 4, because there are 4 Hydrogens and 2 Oxygens on each side of the equation making it balanced.

6 0
3 years ago
Read 2 more answers
Can you pls answer this question cuz i don't know what is the answer on this..
Marysya12 [62]

Answer:

here's is ur answer in attachment

Explanation:

mark it brainliest if it helps you ❤️

3 0
3 years ago
What is the total pressure in atmosphere (atm) of a gas mixture containing argon gas at 0.28 atm, helium gas at 760 mm Hg, and n
siniylev [52]

Answer:

I dont know, sorry!

4 0
3 years ago
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