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timurjin [86]
3 years ago
14

Elements in period 1 are

Chemistry
1 answer:
Ugo [173]3 years ago
6 0

Answer:

Hydrogen - - helium..

...

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Calculate the standard enthalpy of formation of NOCl(g) at 25 ºC, knowing that the standard enthalpy of formation of NO(g) at th
stepan [7]

Answer:

The standard enthalpy of formation of NOCl(g) at 25 ºC is 105 kJ/mol

Explanation:

The ∆H (heat of reaction) of the combustion reaction is the heat that accompanies the entire reaction. For its calculation you must make the total sum of all the heats of the products and of the reagents affected by their stoichiometric coefficient (number of molecules of each compound that participates in the reaction) and finally subtract them:

Enthalpy of the reaction= ΔH = ∑Hproducts - ∑Hreactants

In this case, you have:  2 NOCl(g) → 2 NO(g) + Cl₂(g)

So, ΔH=2*H_{NO} +H_{Cl_{2} }-2*H_{NOCl}

Knowing:

  • ΔH= 75.5 kJ/mol
  • H_{NO}= 90.25 kJ/mol
  • H_{Cl_{2} }= 0 (For the formation of one mole of a pure element the heat of formation is 0, in this caseyou have as a pure compound  the chlorine Cl₂)
  • H_{NOCl}=?

Replacing:

75.5 kJ/mol=2* 90.25 kJ/mol + 0 - H_{NOCl}

Solving

-H_{NOCl}=75.5 kJ/mol - 2*90.25 kJ/mol

-H_{NOCl}=-105 kJ/mol

H_{NOCl}=105 kJ/mol

<u><em>The standard enthalpy of formation of NOCl(g) at 25 ºC is 105 kJ/mol</em></u>

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3 years ago
Carbon naturally occurs in two forms: diamond and graphite. Why do these two forms have very different properties?
Nookie1986 [14]
The differences in the properties of diamond and graphite is as a result of how their particles are arranged in space. This space arrangement leads to distinct crystal structures for the two compounds. In diamond, the carbon atoms are arranged in tetrahedral shape while in graphite the carbon atoms arrayed in planes.
 Hope this helps :)

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Which is true about the total mechanical energy in a closed system?
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It’s between C and B
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If 100% is not passed from one trophic level to the next, where does this energy go?
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D is the answer to question

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Will vote brainliest and 5 star
svetoff [14.1K]

Answer:

it is B

Explanation:

hope it helps you

4 0
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