Chapter 4: Q4.23P (page 178)

Water “softeners” remove metal ions such as and by replacing them with enough ions to maintain the same number of positive charges in the solution. If 1.0 x 10³ L of “hard” water is 0.015 M and 0.0010 M how many moles of are needed to replace these ions?

Short Answer

Expert verified

0.33 mol of ${Na}^{+}$ are needed to replace these ions.

Step by step solution

Calculatethe number of moles of Na+required to remove both Ca2+and Fe3+ metal ions

The no. of moles of ${C a}^{2 +}$ ion in the given sample is:

$\begin{array}{rcl} M o l e s o f {C a}^{2 +} i o n & = & c o n c e n t r a t i o n x v o l u m e \\ = & (0.015 M) (1000 L) = 15 m o l {C a}^{2 +} \end{array}$

Hence, to remove ${Ca}^{2 +}$ ions we need a mole of ${N a}^{+}$

Since the charge onlocalid="1656759165424" $C a^{2 +}$ is twice of ${N a}^{+}$

Hence, to remove a ${Ca}^{2 +}$ ion we need a 2 ${N a}^{+}$ ions

$\begin{array}{rcl} 2 x m o l e s o f {C a}^{2 +} & = & 2 x 15 m o l o f {N a}^{+} \\ = & 30 m o l o f {N a}^{+} \end{array}$

The no. of moles of ${F e}^{+}$ ion in the given sample is:

Since the charge on ${F e}^{3 +}$ is thrice oflocalid="1656760094429" ${N a}^{+}$

Hence, to remove a ${F e}^{3 +}$ ion we need 3 ${N a}^{+}$ ions

$\begin{array}{rcl} 3 x m o l e s o f F e^{3 +} & = & 3 x 1 m o l o f {N a}^{+} \\ = & 3 m o l o f {N a}^{+} \end{array}$

Calculate the total moles of Na+ ion requires to replace of both metal ions Ca2+,Fe3+ :

The total number of moles of ${N a}^{+}$ ions required is:

Moles of ${N a}^{+}$ =30 mol ${N a}^{+}$ +3mol ${N a}^{+}$ =33 mol ${N a}^{+}$

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Water “softeners” remove metal ions such as and by replacing them with enough ions to maintain the same number of positive charges in the solution. If 1.0 x 10³ L of “hard” water is 0.015 M and 0.0010 M how many moles of are needed to replace these ions?

Short Answer

Step by step solution

Calculatethe number of moles of Na+required to remove both Ca2+and Fe3+ metal ions

Calculate the total moles of Na+ ion requires to replace of both metal ions Ca2+,Fe3+ :

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Water “softeners” remove metal ions such as and by replacing them with enough ions to maintain the same number of positive charges in the solution. If 1.0 x 103 L of “hard” water is 0.015 M and 0.0010 M how many moles of are needed to replace these ions?

Short Answer

Step by step solution

Calculatethe number of moles of Na+required to remove both Ca2+and Fe3+ metal ions

Calculate the total moles of Na+ ion requires to replace of both metal ions Ca2+,Fe3+ :

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Chemistry Textbooks

The Earths Atmosphere

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Organic Chemistry

Making Measurements

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Study anywhere. Anytime. Across all devices.

Water “softeners” remove metal ions such as and by replacing them with enough ions to maintain the same number of positive charges in the solution. If 1.0 x 10³ L of “hard” water is 0.015 M and 0.0010 M how many moles of are needed to replace these ions?