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Daniel [21]
3 years ago
13

The image shows the representation of an unknown element in the periodic table.

Chemistry
2 answers:
Mademuasel [1]3 years ago
6 0

Answer is: The sum of the masses of protons and neutrons is 20.1797.

This element (neon) has atomic number (Z) 10, which means it has 10 protons and 10 electrons.

Atomic number (Z) is the number of protons, which is characteristic of a chemical element.

Atomic mass (A) is 20.1797.

Ar is relative atomic mass (the ratio of the average mass of atoms of a chemical element to one unified atomic mass unit) of an element .

Nata [24]3 years ago
4 0

Answer:

the sum of the masses of protons and neutrons is 20.1797

Explanation:

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To fill the valence shell, an electrically neutral, unbonded atom with atomic number 8 must add.
nikdorinn [45]

Answer:

2 electrons

Explanation:

3 0
3 years ago
How many moles of Cu(OH)2 are soluble in 1L of sodium hydroxide (NaOH) when the pH is 8.23?
Morgarella [4.7K]

Answer:

4.96E-8 moles of Cu(OH)2

Explanation:

Kps es the constant referring to how much a substance can be dissolved in water. Using Kps, it is possible to know the concentration of weak electrolytes. Then, pKps is the minus logarithm of Kps.

Now, we know that sodium hydroxide (NaOH) is a strong electrolyte, who is completely dissolved in water. Therefore the pH depends only on OH concentration originating from NaOH. Let us to figure out how much is that OH concentration.

pH= -log[H]\\pH= -log (\frac{kw}{[OH]})

8.23 = - log(\frac{Kw}{[OH]} \\10^{-8.23} = Kw/[OH]\\ [OH] = Kw/10^{-8.23}

[OH]=1.69E-6

This concentration of OH affects the disociation of Cu(OH)2. Let us see the dissociation reaction:

Cu(OH)_2 -> Cu^{2+} + 2OH^-

In the equilibrum, exist a concentration of OH already, that we knew, and it will be added that from dissociation, called "s":

The expression for Kps is:

Kps= [Cu^{2+}] [OH]^2

The moles of (CuOH)2 soluble are limitated for the concentration of OH present, according to the next equation.

Kps= s*(2s+1.69E-6)^2

"s" is the soluble quantity of Cu(OH)2.

The solution for this third grade equation is s=4.96E-8 mol/L

Now, let us calculate the moles in 1 L:

moles Cu(OH)_2 = 4.96E-8 mol/L * 1 L = 4.96E-8 moles

7 0
4 years ago
HELPP
slamgirl [31]

Answer:

In the previous section, we discussed the relationship between the bulk mass of a substance and the number of atoms or molecules it contains (moles). Given the chemical formula of the substance, we were able to determine the amount of the substance (moles) from its mass, and vice versa. But what if the chemical formula of a substance is unknown? In this section, we will explore how to apply these very same principles in order to derive the chemical formulas of unknown substances from experimental mass measurements.

Explanation:

tally. The results of these measurements permit the calculation of the compound’s percent composition, defined as the percentage by mass of each element in the compound. For example, consider a gaseous compound composed solely of carbon and hydrogen. The percent composition of this compound could be represented as follows:

\displaystyle \%\text{H}=\frac{\text{mass H}}{\text{mass compound}}\times 100\%%H=

mass compound

mass H

×100%

\displaystyle \%\text{C}=\frac{\text{mass C}}{\text{mass compound}}\times 100\%%C=

mass compound

mass C

×100%

If analysis of a 10.0-g sample of this gas showed it to contain 2.5 g H and 7.5 g C, the percent composition would be calculated to be 25% H and 75% C:

\displaystyle \%\text{H}=\frac{2.5\text{g H}}{10.0\text{g compound}}\times 100\%=25\%%H=

10.0g compound

2.5g H

×100%=25%

\displaystyle \%\text{C}=\frac{7.5\text{g C}}{10.0\text{g compound}}\times 100\%=75\%%C=

10.0g compound

7.5g C

×100%=75%

7 0
3 years ago
How many moles are in 47.5 g of Ca?<br> A.2.85 e 25<br> B.1.18 mol<br> C. 7.89 e-23<br> D.1900 mol
docker41 [41]
Okfjchchcjcjjcjccjbfhf
3 0
3 years ago
Compare S (secondary) waves and P (primary) waves. Why do they travel at different speeds?
Amanda [17]

S waves

  • These are shear waves .
  • The motion of the medium is perpendicular to  direction of propagation of the wave .
  • They can propagate only through solids and not through gases or liquids .
  • S waves are larger .
  • They travel with less speed .

P waves

  • These are compression waves .
  • These waves produces a force along the direction of propagation .
  • They can propagate through solids, gases and liquids.
  • P waves are smaller than s waves .
  • They travel with 60% greater speed than S waves .

P-waves travel 60% faster than S-waves on average because the interior part of the Earth does not react the same way as the s wave and P wave.

8 0
4 years ago
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