Concept explainers
The scvcn most abundant ions in seawater make up more than 99% by mass of the dissolved compounds. Here are their abundances in units of mg ion/kg seawater: chloride 18,980; sodium 10,560; sulfate 2650; magnesium 1270; calcium 400; potassium 380; hydrogcn carbonate 140.
(a) What is thc mass % of each ion in seawater?
(b) What çcrccnt of the total mass of ions is sodium ion?
(c) How does the total mass % of alkaline earth metal ions compare with the total mass % of alkali metal ions?
(d) Which make up the larger mass fraction of dissolved compon ents, anions or cations?
a)
Interpretation:Mass
Concept introduction:Mass
Calculation of mass
Answer to Problem 2.91P
Mass
Explanation of Solution
Given Information: In
Mass
Formula to calculate the mass
Total mass of seawater is
Formula to calculate the mass
Mass of chloride ion is
Total mass of seawater is
Substitute the values in above formula.
Formula to calculate the mass
Mass of sodium ion is
Total mass of seawater is
Substitute the values in above formula.
Formula to calculate the mass
Mass of sulfate ion is
Total mass of seawater is
Substitute the values in the above formula.
Formula to calculate the mass
Mass of magnesium ion is
Total mass of seawater is
Substitute the values in the above formula.
Formula to calculate the mass
Mass of calcium ion is
Total mass of seawater is
Substitute the values in the above formula.
Formula to calculate the mass
Mass of ium ion is
Total mass of seawater is
Substitute the values in the above formula.
Formula to calculate the mass
Mass of hydrogen carbonate ion is
Total mass of seawater is
Substitute the values in the above formula.
b)
Interpretation: Mass
Concept introduction: Mass
Formula to calculate mass
Answer to Problem 2.91P
Mass
Explanation of Solution
Given Information: In
Mass
Formula to calculate the mass
Total mass of ionsin
Formula to calculate the mass
Mass of sodium ion is
Total mass of ion is
Substitute the values in above formula.
c)
Interpretation: Mass
Concept introduction: Mass
Formula to calculate mass
Answer to Problem 2.91P
Total mass percent for alkali metal ions is
Explanation of Solution
Given Information: In
Expression to calculate ratio of mass
Mass
Mass
Substitute the values in above formula.
Therefore, total mass percent for alkali metal ions is
d)
Interpretation:Cation or anion that has larger mass fraction of dissolved component is to be identified.
Concept introduction: Mass fraction is a method of representation of concentration of an element in a compound or a component mixture.
Calculation of mass fraction is done as follows:
Explanation of Solution
Given Information: In
Mass fraction is a method of representation of concentration of an element in a compound or a component mixture.
Formula to calculate mass fraction is as follows:
Total mass of ions in
Total mass of cation is calculated follows:
Formula to calculate the mass fraction of cation, among total mass of ion is as follows:
Mass of cation is
Total mass of ion is
Substitute the values in the above formula.
Total mass of anion is calculated follows:
Formula to calculate the mass fraction of anion, among total mass of ion is as follows:
Mass of anion is
Total mass of ion is
Substitute the values in the above formula.
Hence, mass fraction of anion in seawater is greater than that of mass fraction of cation.
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Chapter 2 Solutions
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