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lyudmila [28]
3 years ago
14

"the number of quantum numbers needed to describe the state of an atomic electron is"

Chemistry
1 answer:
Blababa [14]3 years ago
5 0
To completely describe an electron in an atom, four quantum numbers are needed: energy (n), angular momentum (ℓ), magnetic moment (mℓ), and spin (ms). The first quantum number describes the electron shell, or energy level, of an atom.
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Manganese dioxide (MnO2(s), Hf = –520.0 kJ) reacts with aluminum to form aluminum oxide (AI2O3(s), Hf = –1699.8 kJ/mol) and mang
Temka [501]

Answer : The enthalpy of the reaction = -1839.6 KJ

Solution : Given,

\Delta (H_{f})_{MnO_{2}} = -520.0 KJ/mole

\Delta (H_{f})_{Al_{2}O_{3}} = -1699.8 KJ/mole

The balanced chemical reaction is,

3MnO_{2}(s)+4Al(s)\rightarrow 2Al_{2}O_{3}(s)+3Mn(s)

Formula used :

\Delta (H_{f})_{reaction}=\sum n(\Delta H_{f})_{product}-\sum n(\Delta H_{f})_{reactant}

\Delta (H_{f})_{reaction}=(2\times \Delta H_{Al_{2}O_{3}(s)}+3\times \Delta H_{Mn(s)} )-(3\times \Delta H_{MnO_{2}(s) }+4\times\Delta H_{Al}(s))

We know that the standard enthalpy of formation of the element is equal to Zero.

Therefore, the enthalpy of formation of (Mn) and (Al) is equal to zero.

Now, put all the values in above formula, we get

\Delta (H_{f})_{reaction}=[2moles\times (-1699.8 KJ/mole)}+3moles\times (0\text{ KJ/mole}})]-[(3moles\times(-520.0KJ/mole }+4moles\times(0\text{ KJ/mole})]

                        = (-3399.6) + (1560)

                        = -1839.6 KJ



5 0
3 years ago
What will the charge oxidiation state be for boron
artcher [175]

3+

So, compounds of boron contain boron in a positive oxidation state, generally +3. The sum of oxidation numbers of all constituent atoms of a given molecule or ion is equal to zero or the charge of the ion, respectively. ... In most of the stable compounds of boron, its oxidation number is +3

7 0
3 years ago
An element that speeds up chemical reactions is called a/an
mel-nik [20]
I think it is enzymes.Inside our body most of the chemical reactions are speeds up by enzymes.These enzymes decreases the minimum energy that is required for the reaction to happen. ;-]. Actually it works like a catalyst.
7 0
3 years ago
Calculate the mass of ethyl alcohol required to prepare 540 grams of C4H6, if the reaction follows the scheme:
kkurt [141]

Answer:

Explanation:

2C₂H₅OH    =   C₄H₆  +  2H₂O  +  H₂

2 mole               1 mole

molecular weight of ethyl alcohol

mol weight of C₂H₅OH = 46 gm            

mol weight of C₄H₆  54 gm

540 gm of C₄H₆ = 10 mole

10 mole of C₄H₆ will require 20 mol of ethyl alcohol .

20 mole of ethyl alcohol = 20  x 46

= 920 gm

ethyl alcohol required = 920 gm .

3 0
3 years ago
The notation for a particular nucleus is r3785b. in an electrically neutral atom. How many electrons are in orbit about this nuc
Serhud [2]

^{85}_{37}Rb has 37 electrons in the orbit about its nucleus.

<h3>How to write an atomic symbol with atomic mass and atomic number?</h3>

Atomic mass is the total number of neutrons and protons present in the nucleus of an element.

The atomic number is the total number of protons present in the nucleus of an element.

For writing an atomic symbol, atomic mass is written on the top left of the atomic symbol, and the atomic number is written on the downside of the left of the symbol.

^{Atomic mass}_{Atomic number}X

An electrically neutral atom is an atom that has an equal number of electrons as well as protons.

Thus from the above conclusion we can say that  ^{85}_{37}Rb has 37 electrons.

Learn more about Atomic mass and atomic number here:

brainly.com/question/3187640

#SPJ4

3 0
1 year ago
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