What is the molarity of each ion present in aqueous solutions of the following compounds prepared by dissolving 28.0 g of each compound in water to make 785 mL of solution?
(a) potassium oxide
(b) sodium hydrogen carbonate
(c) scandium(III) iodite
(d) magnesium phosphate
(a)
Interpretation:
The molarity of all the ions in the solution should be calculated.
Concept introduction:
The number of moles of a substance is related to mass and molar mass as follows:
Here, m is mass and M is molar mass of the substance.
Also, according to Avogadro’s law in 1 mol of a substance there are
The molarity of a solution is defined as number of moles of solute in 1 L of the solution. It is mathematically represented as follows:
Here, n is number of moles of solute and V is volume of solution in L. Thus, the unit of molarity is mol/L.
Answer to Problem 18QAP
The molarity of
Explanation of Solution
The given compound is potassium oxide. The mass of compound is 28.0 g and volume of solution is 785 mL. The number of moles of compound can be calculated as follows:
Molar mass of potassium oxide is 94.2 g/mol thus,
Thus, number of moles of potassium oxide is 0.297 mol. Molarity of solution can be calculated as follows;
Convert the volume from mL to L.
Putting the values,
Therefore, molarity of solution is
The formula of potasisum oxide is
And, molarity of
Thus,
(b)
Interpretation:
The molarity of all the ions in the solution should be calculated.
Concept introduction:
The number of moles of a substance is related to mass and molar mass as follows:
Here, m is mass and M is molar mass of the substance.
Also, according to Avogadro’s law in 1 mol of a substance there are
The molarity of a solution is defined as number of moles of solute in 1 L of the solution. It is mathematically represented as follows:
Here, n is number of moles of solute and V is volume of solution in L. Thus, the unit of molarity is mol/L.
Answer to Problem 18QAP
Molarity of both
Explanation of Solution
The given compound is sodium hydrogen carbonate. The mass of compound is 28.0 g and volume of solution is 785 mL. The number of moles of compound can be calculated as follows:
Molar mass of sodium hydrogen carbonate is 84.0 g/mol thus,
Thus, number of moles of sodium hydrogen carbonate is 0.33 mol. Molarity of solution can be calculated as follows;
Convert the volume from mL to L.
Putting the values,
Therefore, molarity of solution is
The molecular formula of sodium hydrogen carbonate is
The molarity of sodium hydrogen carbonate is equal to the molarity of
Therefore, molarity of both
(c)
Interpretation:
The molarity of all the ions in the solution should be calculated.
Concept introduction:
The number of moles of a substance is related to mass and molar mass as follows:
Here, m is mass and M is molar mass of the substance.
Also, according to Avogadro’s law in 1 mol of a substance there are
The molarity of a solution is defined as number of moles of solute in 1 L of the solution. It is mathematically represented as follows:
Here, n is number of moles of solute and V is volume of solution in L. Thus, the unit of molarity is mol/L.
Answer to Problem 18QAP
Molarity of Sc3+ and I- is 0.068 M and 0.204 M respectively.
Explanation of Solution
The given compound is scandium (III) iodite. The mass of compound is 28.0 g and volume of solution is 785 mL. The number of moles of compound can be calculated as follows:
Molar mass of scandium (III) iodite is 521.66 g/mol thus,
Thus, number of moles of scandium (III) iodide is 0.054 mol. Molarity of solution can be calculated as follows;
Convert the volume from mL to L.
Putting the values,
Therefore, molarity of solution is
The molecular formula of scandium (III) iodite is
Thus, molarity of IO2 - is
Therefore, molarity of Sc3+ and I- is 0.068 M and 0.204 M respectively.
(d)
Interpretation:
The molarity of all the ions in the solution should be calculated.
Concept introduction:
The number of moles of a substance is related to mass and molar mass as follows:
Here, m is mass and M is molar mass of the substance.
Also, according to Avogadro’s law in 1 mol of a substance there are
The molarity of a solution is defined as number of moles of solute in 1 L of the solution. It is mathematically represented as follows:
Here, n is number of moles of solute and V is volume of solution in L. Thus, the unit of molarity is mol/L.
Answer to Problem 18QAP
The molarity of
Explanation of Solution
The given compound is magnesium phosphate. The mass of compound is 28.0 g and volume of solution is 785 mL. The number of moles of compound can be calculated as follows:
Molar mass of magnesium phosphate is 262.85 g/mol thus,
Thus, number of moles of potassium oxide is 0.297 mol. Molarity of solution can be calculated as follows;
Convert the volume from mL to L.
Putting the values,
Therefore, molarity of solution is
The formula of magnesium phosphate is
The molarity of
Therefore, the molarity of
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Chapter 3 Solutions
Chemistry: Principles and Reactions
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