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3 years ago

The wavelength idea of the wave-mechanical model refers to what?

1 answer:

6 0

<span> The wave idea derives from the electrons' behavior about the nucleus of an atom, and it follows Heisenberg's Uncertainty Principle and draws away from Bohr's planetary model of the atom.</span>

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30 POINTS! ----- How many moles of oxygen gas are needed to completely react with 145 grams of aluminum? Report your answer with

gladu [14]

First a balanced reaction equation must be established:
$4Al _{(s)} + 3 O_{2} _{(g)}$ → $2 Al_{2} O_{3}$

Now if mass of aluminum = 145 g
the moles of aluminum = (MASS) ÷ (MOLAR MASS) = 145 g ÷ 30 g/mol
= 4.83 mols

Now the mole ratio of Al : O₂ based on the equation is 4 : 3
[4Al + 3 O₂ → 2 Al₂O₃]

∴ if moles of Al = 4.83 moles
then moles of O₂ = (4.83 mol ÷ 4) × 3
= 3.63 mol (to 2 sig. fig.)

Thus it can be concluded that 3.63 moles of oxygen is needed to react completely with 145 g of aluminum.

4 0

3 years ago

PLZ HELP ME What are the five shared characteristics of all living things?

djverab [1.8K]

Answer:

Explanation:

I believe the answer is D.

5 0

3 years ago

An example of an extensive property of matter is

timurjin [86]

An example of an extensive property of matter is "mass"

6 0

3 years ago

Read 2 more answers

If 21.00 mL of a 0.68 M solution of C6H5NH2 required 6.60 mL of the strong acid to completely neutralize the solution, what was

Andru [333]

Answer:

pH = 2.46

Explanation:

Hello there!

In this case, since this neutralization reaction may be assumed to occur in a 1:1 mole ratio between the base and the strong acid, it is possible to write the following moles and volume-concentrations relationship for the equivalence point:

$n_{acid}=n_{base}=n_{salt}$

Whereas the moles of the salt are computed as shown below:

$n_{salt}=0.021L*0.68mol/L=0.01428mol$

So we can divide those moles by the total volume (0.021L+0.0066L=0.0276L) to obtain the concentration of the final salt:

$[salt]=0.01428mol/0.0276L=0.517M$

Now, we need to keep in mind that this is an acidic salt since the base is weak and the acid strong, so the determinant ionization is:

$C_6H_5NH_3^++H_2O\rightleftharpoons C_6H_5NH_2+H_3O^+$

Whose equilibrium expression is:

$Ka=\frac{[C_6H_5NH_2][H_3O^+]}{C_6H_5NH_3^+}$

Now, since the Kb of C6H5NH2 is 4.3 x 10^-10, its Ka is 2.326x10^-5 (Kw/Kb), we can also write:

$2.326x10^{-5}=\frac{x^2}{0.517M}$

Whereas x is:

$x=\sqrt{0.517*2.326x10^{-5}}\\\\x=3.47x10^-3$

Which also equals the concentration of hydrogen ions; therefore, the pH at the equivalence point is:

$pH=-log(3.47x10^{-3})\\\\pH=2.46$

Regards!

6 0

3 years ago

State, in terms of the arrangement of atoms, the difference in hardness between diamond and graphite.

sleet_krkn [62]

The difference in hardness between diamond and graphite is that diamond has an ordered arrangement of atoms within its structure that makes it harder and stronger than graphite. This is due to the high pressure and high temperature that it went.

7 0

3 years ago