What type of energy does a saxophone player have and what energy does it turn into

Solid sodium reacts violently with water, producing heat, hydrogen gas, and sodium hydroxide. How many molecules of hydrogen gas

Zinaida [17]

Answer: Number of molecules of hydrogen gas $6.32\times 10^{32}$

Explanation:

$2Na+2H_2O\rightarrow 2NaOH+H_2$

Number of moles of sodium = $\frac{\text{mass of sodium}}{\text{molar mass of sodium}}=\frac{48.7 g}{23 g/mol}=2.11mol$

According to reaction , 2 moles of sodium produces 1 mole of hydrogen gas , then 2.11 mol of sodium will= $\frac{1}{2}\times 2.11 mol$ of hydrogen gas that is 1.05 moles of hydrogen gas.

Number of molecules = $N_A(\text{Avogadro number})\times$ moles of substance

Moles of hydrogen gas formed = 1.05 moles

Number of molecules of hydrogen gas = $N_A\times$ moles of hydrogen gas

Number of molecules of hydrogen gas $=6.022\times 10^{23} mole^{-1}\times 1.05 mole=6.32\times 10^{32}$

8 0

3 years ago

Calculate the molar solubility of silver(i) bromate with ksp = 5. 5×10-5. also, convert the molar solubility to the solubility.

Sindrei [870]

The molar solubility is 7.4× $10^{-3}$ M and the solubility is 7.4× $10^{-3}$ g/L .

Calculation ,

The dissociation of silver bromide is given as ,

$AgBr$ → $Ag ^{+}$ + $Br^{-}$

S

- S S

Ksp = [ $Ag ^{+}$ ] [ $Br^{-}$ ] = [S] [ S ] = $S^{2}$

S = √ Ksp = √ 5. 5× $10^{-5}$ = 7.4× $10^{-3}$

The solubility =7.4× $10^{-3}$ g/L

The molar solubility is the solubility of one mole of the substance.

Since , one mole of $AgBr$ is dissociates and form one mole of each $Ag ^{+}$ and $Br^{-}$ ion . So, solubility is equal to molar solubility but unit is different.

Molar solubility = 7.4× $10^{-3}$ mol/L = 7.4× $10^{-3}$ M

To learn more about molar solubility ,

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7 0

1 year ago

What is the pH of a 0.028M solution (pH= -log(M)) A) 3.56 B) 2.88 C) 1.55 D) 1

kupik [55]

Answer:

1.55

Explanation:

-log(M)=pH

- Hope that helps! Please let me know if you need further explanation.

4 0

3 years ago

Chechnya. 345. Gcbjshjkfs

3 0

3 years ago

Suppose a laboratory wants to identify an unknown pure substance. The valence electrons of the substance's atoms feel an effecti

zalisa [80]

Answer:

The answer is the third option in the list: It would have smaller atomic radii than Si and higher ionization energies than Si.

Explanation:

The effective nuclear charge is that portion of the total nuclear charge that a given electron in an atom feels.

Since, the inner electrons repel the outer electrons, the effective nuclear charge of a determined electron is the sum of the positive charge (number of protons or atomic number) that it feels from the nucleus less the number of electrons that are in the shells that are are closer to the nucleus than the own shell of such (determined) electron.

Mathematically, the effective nuclear charge (Zeff) is equal to the atomic number (Z) minus the amount (S) that other electrons in the atom shield the given (determined) atom from the nucleus.

Zeff = Z - S.

Since, the valence electrons are the electrons in the outermost shell of the atom, you can find certain trend for the value Zeff.

Let's look at the group to which Si belongs, which is the group 14. This table summarizes the relevant data:

Element Z Group # valence electrons S Zeff = Z - S

C 6 14 4 6 - 4 = 2 6 - 2 = +4

Si 14 14 4 14 - 4 = 10 14 - 10 = +4

Ge 32 14 4 32 - 4 = 28 32 -28 = +4

Sn 50 14 4 50 - 4 = 46 50 - 46 = +4

Pb 82 14 4 82 - 4 = 78 82 - 78 = +4

With that, you have shown that the valence electrons of the unknown substance's atoms feel an effective nuclear charge of +4 and you have a short list of 4 elements which can be the unknown element: C, Ge, Sn or Pb.

The second known characteristic of the unknown substance's atoms is that it has a higher electronegativity than silicon (Si).

So, you must use the known trend of the electronegativity in a group of the periodic table: the electronegativity decreases as you go down in a group. So, three of the elements (Ge, Sn, and Pb) have lower electronegativity than Si, which has left us with only one possibility: the element C. The valence electrons of carbon (C) atoms feel an effective nuclear charge of +4 and it carbon has a higher electronegativity than silicon.

Other two periodic trends attending the group number are the atomic radii and the ionization energy.

The atomic radii generally increases as you go from top to bottom in a group. This is because you are adding electrons to new higher main energy levels. So, you can conclude that the originally unknwon substance (carbon) has a smaller atomic radii, than Si.

The ionization energies generally decreases as you go from top to bottom in a group. This os due to the shielding effect: as seen, the effective nuclear charge of the atom's valence electrons remains constant, while the distance of the electrons from the nucleus increases (the valence electrons are farther away from the nucleus), which means the upper the element in a given group, the larger the ionization energy of the atoms.

With this, our conclusions about the unnkown substance are:

Since it has a higher electronegativity value than silicon (Si), it is right up of Si, and there is on only element possible element than can be (C).

Since, it is upper than silicon (Si), it would have smaller atomic radii.

Due to the shielding effect, it would have larger ionization energies.

The answer is the third option in the list: It would have smaller atomic radii than Si and higher ionization energies than Si.

6 0

3 years ago