Respuesta :
41) Answer is: the average atomic mass of chromium is 52.056.
Ar(⁵⁰Cr) = 50.
ω(⁵⁰Cr) = 4.34% ÷ 100%.
ω(⁵⁰Cr) = 0.0434; relative abundance of chromium-50.
Average mass can calculate by summary of percentege of each isotope.
Ar(Cr) = Ar(⁵⁰Cr) · ω(⁵⁰Cr) + Ar(⁵²Cr) · ω(⁵²Cr) + Ar(⁵³Cr) · ω(⁵³Cr) + Ar(⁵⁴Cr) · ω(⁵⁴Cr).
Ar(Cr)= 50 · 0.0434 + 52 · 0.8379 + 53 · 0.095 + 54 · 0.0237.
Ar(Cr) = 2.17 + 43.571 + 5.035 + 1.280
Ar(Cr) = 52.056.
42) Chlorine has atomic number 17, it means it has 17 protons and 17 electrons.
Electron configuration of chlorine atom: ₁₇Cl 1s² 2s² 2p⁶ 3s² 3p⁵.
Chloride is negative ion of chlorine. Chloride is formed when chlorine gain one lectron.
Chloride anion has 17 protons and 18 electrons (like argon-noble gas).
The electron configuration for the chloride ion: ₁₇Cl⁻ 1s²2s²2p⁶3s²3p⁶.
43) Anwser is: the percent by mass of hydrogen in aspirin is 4.48%.
% calculate by atomic mass of element multiply number of that element in molecule divided by molecular mass of molecule.
Ar(H) = 1.008; the relative atomic mass of hydrogen atom.
Mr(C₉H₈O₄) = 9 · Ar(C) + 8 · Ar(H) + 4 · Ar(O).
Mr(C₉H₈O₄) = 180.157.
ω(H)= 8 · Ar(H) ÷ Mr(C₉H₈O₄) · 100%.
ω(H) = 8 · 1.008 ÷ 180.157 · 100%.
ω(H) = 4.48 %.
44) Balanced chemical reaction:
Cd(NO₃)₂ + 2NH₄Cl → CdCl₂ + 2NH₄NO₃.
This chemical reaction is double displacement reaction - cations (Cd²⁺ and NH₄⁺) and anions (NO₃⁻ and Cl⁻) of the two reactants switch places and form two new compounds.
Cd(NO₃)₂ is cadmium nitrate.
NH₄Cl is amonium chloride.
CdCl₂ is cadmium chloride.
NH₄NO₃ is ammonium nitrate.
The average atomic mass of Chromium is 52.0556.
The electronic configuration of Chloride ion is [tex]\rm 1s^2\;2s^2\;2p^6\;3s^2\;3p^6[/tex].
The percent by mass of hydrogen in aspirin is 4.47%.
The balanced equation is : [tex]\rm Cd(NO_3)_2\;+\;2\;NH_4Cl\;\rightarrow\;CdCl_2\;+\;2\;NH_4NO_3[/tex].
41) The average atomic mass of the isotopes from its relative abundance has been given by:
average mass = (mass of a [tex]\times[/tex] % abundance of a) + (mass of b [tex]\times[/tex] % abundance of b) + (mass of c [tex]\times[/tex] % abundance of c) ......
Given, the isotopes are:
Cr 50 = 4.34%
Cr 52 = 83.79 %
Cr 53 = 9.50 %
Cr 54 = 2.37 %
Average mass = (50 [tex]\times[/tex] [tex]\rm \dfrac{4.34}{100}[/tex]) + (52 [tex]\times[/tex] [tex]\rm \dfrac{83.79}{100}[/tex]) + (53 [tex]\times[/tex] [tex]\rm \dfrac{9.50}{100}[/tex]) + (54 [tex]\times[/tex][tex]\rm \dfrac{2.37}{100}[/tex])
Average mass = 2.17 + 43.5708 + 5.035 + 1.2798
Average mass = 52.0556.
The average atomic mass of chromium is 52.0556.
42) The chloride ion is the one that gains an electron for the octet formation.
The atomic number of Chlorine is = 17.
The atomic number of Chloride ion = 17 + 1
The atomic number of chloride ion is 18.
The electronic configuration will be: [tex]\rm 1s^2\;2s^2\;2p^6\;3s^2\;3p^6[/tex].
43) The percent by mass can be calculated by the ratio of mass to the total mass.
In the molecule of aspirin, the number of hydrogen atoms are 8.
The mass of hydrogen in aspirin will be = molar mass [tex]\times[/tex] number of atoms
The mass of Hydrogen in aspirin = 1.008 [tex]\times[/tex] 8
The mass of hydrogen in aspirin = 8.064 g.
The total mass of aspirin = 180.157 g/mol.
The mass percent of Hydrogen = [tex]\rm \dfrac{mass\;of\;hydrogen}{Total\;mass}\;\times\;100[/tex]
The mass percent of Hydrogen = [tex]\rm \dfrac{8.064}{180.157} \;\times\;100[/tex]
The mass percent of Hydrogen = 4.47 %
44) The equation can be completed as:
[tex]\rm Cd(NO_3)_2\;+\;NH_4Cl\;\rightarrow\;CdCl_2\;+\;NH_4NO_3[/tex]
The balanced chemical equation will be:
[tex]\rm Cd(NO_3)_2\;+\;2\;NH_4Cl\;\rightarrow\;CdCl_2\;+\;2\;NH_4NO_3[/tex].
For more information, refer to the link:
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