Calculate the number of moles of magnesium, chlorine, and oxygen atoms in 7.30 moles of magnesium perchlorate, Mg(CLO4)2

A 13.5 g sample of an unknown gas occupies 5.10 L at 149.83 kPa and 301 K. What is the molar mass of the gas ?

alisha [4.7K]

Answer:

The molar mass of the gas is 44.19 g/mol

Explanation:

Amount of sample of gas = m = 13.5 g

Volume occupied by the gas = V = 5.10 L

Pressure of the gas = P = 149.83 KPa

1 KPa = 0.00986 atm

P = $149.83 \textrm{ KPa} \times 0.00986 \textrm{ atm/KPa} = 1.48 \textrm{ atm}$

Assuming M g/mol to be the molar mass of the gas

Assuming the gas is behaving as an ideal gas

$\textrm{PV} =\textrm{nRT} \\\textrm{PV} = \displaystyle \frac{m}{M}\textrm{ RT } \\1.48 \textrm{ atm}\times 5.10 \textrm{ L} = \displaystyle \frac{13.5 \textrm{ g}}{M}\times 0.0821 \textrm{ L.atm.mol}^{-1}.K^{-1}\times 301\textrm{K} \\M = 44.19 \textrm{ g/mol}$

The molar mass of gas is 44.19 g/mol

7 0

3 years ago

Question 2 (1 point)

Vikki [24]

Answer:D

Explanation:

Jus did this question & got it right

4 0

3 years ago

Rank the following elements by effective nuclear charge, Zeff, for a valence electron. F LI Be B N

Stels [109]

Answer:

Rank in increasing order of effective nuclear charge:

Li < Be < B < N < F

Explanation:

This explains the meaning of effective nuclear charge, Zeff, how to determine it, and the calculations for a valence electron of each of the five given elements: F, Li, Be, B, and N.

1) Effective nuclear charge definitions

While the total positive charge of the atom nucleus (Z) is equal to the number of protons, the electrons farther away from the nucleus experience an effective nuclear charge (Zeff) less than the total nuclear charge, due to the fact that electrons in between the nucleus and the outer electrons partially cancel the atraction from the nucleus.

Such effect on on a valence electron is estimated as the atomic number less the number of electrons closer to the nucleus than the electron whose effective nuclear charge is being determined: Zeff = Z - S.

2) Z eff for a F valence electron:

F's atomic number: Z = 9
Total number of electrons: 9 (same numer of protons)
Period: 17 (search in the periodic table or do the electron configuration)
Number of valence electrons: 7 (equal to the last digit of the period's number)
Number of electrons closer to the nucleus than a valence electron: S = 9 - 7 = 2
Zeff = Z - S = 9 - 2 = 7

3) Z eff for a Li valence eletron:

Li's atomic number: Z = 3
Total number of electrons: 3 (same number of protons)
Period: 1 (search on the periodic table or do the electron configuration)
Number of valence electrons: 1 (equal to the last digit of the period's number)
Number of electrons closer to the nucleus than a valence electron: S = 3 - 1 = 2
Z eff = Z - S = 3 - 2 = 1.

4) Z eff for a Be valence eletron:

Be's atomic number: Z = 4
Total number of electrons: 4 (same number of protons)
Period: 2 (search on the periodic table or do the electron configuration)
Number of valence electrons: 2 (equal to the last digit of the period's number)
Number of electrons closer to the nucleus than a valence electron: S = 4 - 2 = 2
Z eff = Z - S = 4 - 2 = 2

5) Z eff for a B valence eletron:

B's atomic number: Z = 5
Total number of electrons: 5 (same number of protons)
Period: 13 (search on the periodic table or do the electron configuration)
Number of valence electrons: 3 (equal to the last digit of the period's number)
Number of electrons closer to the nucleus than a valence electron: S = 5 - 3 = 2
Z eff = Z - S = 5 - 2 = 3

6) Z eff for a N valence eletron:

N's atomic number: Z = 7
Total number of electrons: 7 (same number of protons)
Period: 15 (search on the periodic table or do the electron configuration)
Number of valence electrons: 5 (equal to the last digit of the period's number)
Number of electrons closer to the nucleus than a valence electron: S = 7 - 5 = 2
Z eff = Z - S = 7 - 2 = 5

7) Summary (order):

Atom Zeff for a valence electron

F 7

Li 1

Be 2

B 3

N 5

Conclusion: the order is Li < Be < B < N < F

6 0

3 years ago

) Calculate the number of moles of sulfuric acid that is contained in 250 mL of 0.500 M sulfuric acid solution

maksim [4K]

Explanation:

According to the analysis, Molarity is amount mole per volume(1L). the amount in mole would be molarity × volume in litres.

0.500M × (250/1000)L= 0.125moles.

I hope this helps**

3 0

3 years ago

Why is it important to use scientific notation when talking about our solar system and galaxies?

IgorLugansk [536]

Answer:

The main purpose for converting numbers into scientific notation is to make calculations with surpisingly large or small numbers less complicated. Since zeros are not used to place the decimal point, all of the digits in a number in scientific notation are meaningful and easier to read. Hope this helps!

Explanation:

3 0

2 years ago