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sladkih [1.3K]
3 years ago
15

What is the electron configuration for La (lanthanum)?

Chemistry
1 answer:
MrRissso [65]3 years ago
7 0

Answer:

Lathanum .

Atomic number = 57

Symbol = La

Atomic weight = 138.9

No of energy orbitals = 6

Electronic configuration

[Xe]6s^25d^1

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Calculate the energy of a photon of this light wave in joules. [Show all calculations, including the equation and substitution w
Ket [755]

The energy of the photon from the calculation performed is 3.5 * 10^-16 J.

<h3>What is a photon?</h3>

A photon is a packet of light. It was derived from the theory of Albert Einstein. The energy of a photon is obtained from; E = hc/λ

  • h= Plank's constant
  • c = speed of light
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Now we have that;

E = 6.6 * 10^-34 * 3 * 10^8/562 * 10^-9

E = 3.5 * 10^-16 J

Missing parts:

Calculate the energy, in joules, of a photon of green light having a wavelength of 562nm?

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7 0
2 years ago
what is an empirical formulaWhat is the percent composition by mass of nitrogen in (NH4)2CO3 (gram-formula mass = 96.0 g/mol)?
Margarita [4]

Answer:

Percentage composition = 14.583%

Explanation:

In chemistry, the emprical formular of a compound is the simplest formular a compound can have. It shows the simplest ratio in which the elements are combined in the compound.

Percentage composition by mass of Nitrogen

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In one mole of the compound;

Mass of Nitrogen = 1 mol * 14g/mol = 14g

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Percentage composition of Nitrogen = (Mass of Nitrogen /  Mass of compound) * 100

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3 0
3 years ago
Help ASAP!!! I need it now i have to write similar test tmrw
dusya [7]
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The diagram shows that the reaction is exothermic based on the fact that the products energy is lower than the reactants. That is because energy (which is temperature in this case) is released during the process. If the reactants would have been lower than the products, the reaction would be endothermic.
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labwork [276]
Water is H2O but I'm not sure about solids. 
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3 years ago
In your discussion consider a SN2 reaction mechanism concept. Propose a modification of experimental procedure that would improv
Hitman42 [59]

Answer:

Here's what I get  

Explanation:

You may have done a Williamson synthesis of guaifenesin by reacting guaiacol with 3-chloropropane-1,2-diol.

A. Mechanism

Step 1

NaOH converts guaiacol into a phenoxide ion.

Step 2

The phenoxide acts as the nucleophile in an SN2 reaction to displace the Cl from the alkyl halide.

B. Improve the yield

You probably carried out the reaction in ethanol solution — a polar protic solvent.

You might try doing the reaction in a polar aprotic solvent— perhaps DMSO.

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6 0
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