When permanent hard water is treated with slaked lime (calcium hydroxide), the reaction occurs as follows:
Ca2+ + 2HCO3- + Ca(OH)2 ⟶ 2CaCO3 + 2H2O
In this reaction, the calcium ions (Ca2+) and bicarbonate ions (HCO3-) present in the hard water react with slaked lime (calcium hydroxide) to form calcium carbonate (CaCO3) and water (H2O). The calcium carbonate is insoluble and precipitates out of the solution, leaving the water softer.
Similarly, when permanent hard water is treated with washing soda (sodium carbonate), the reaction occurs as follows:
Ca2+ + 2HCO3- + Na2CO3 ⟶ CaCO3 + 2Na+ + 2H2O
In this reaction, the calcium ions (Ca2+) and bicarbonate ions (HCO3-) present in the hard water react with washing soda (sodium carbonate) to form calcium carbonate (CaCO3), sodium ions (Na+), and water (H2O). Again, the calcium carbonate precipitates out of the solution, making the water softer.
Both slaked lime and washing soda act as precipitating agents in the treatment of hard water. The precipitated calcium carbonate can then be filtered or removed, resulting in the removal of hardness from the water.
When permanent hard water is treated with slaked lime (calcium hydroxide, Ca(OH)2) or washing soda (sodium carbonate, Na2CO3), the hardness causing minerals in the water (usually calcium and magnesium ions) react with these compounds to form insoluble precipitates.
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1. When treated with slaked lime (calcium hydroxide):
➙The equation for the reaction with calcium hydroxide is as follows:
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➙Ca(HCO3)2+Ca(OH)2→2CaCO3+2H2O
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➙The calcium bicarbonate present in the hard water reacts with calcium hydroxide to form insoluble calcium carbonate, which is a white precipitate that settles down as a solid.
The resulting water becomes soft and free from calcium and magnesium ions.
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2. When treated with washing soda (sodium carbonate):
➙The equation for the reaction with washing soda is as follows:
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➙Ca(HCO3)2+Na2CO3→CaCO3+2NaHCO3
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➙Similar to the reaction with slaked lime, the calcium bicarbonate reacts with washing soda to form insoluble calcium carbonate as a white precipitate, along with sodium bicarbonate, which remains dissolved in the water.
The water is now softened and contains sodium bicarbonate.
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Both slaked lime and washing soda effectively remove the calcium and magnesium ions responsible for the hardness in the water, leading to the formation of insoluble calcium carbonate precipitates that can be separated from the softened water.
Answers & Comments
Explanation:
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When permanent hard water is treated with slaked lime (calcium hydroxide), the reaction occurs as follows:
Ca2+ + 2HCO3- + Ca(OH)2 ⟶ 2CaCO3 + 2H2O
In this reaction, the calcium ions (Ca2+) and bicarbonate ions (HCO3-) present in the hard water react with slaked lime (calcium hydroxide) to form calcium carbonate (CaCO3) and water (H2O). The calcium carbonate is insoluble and precipitates out of the solution, leaving the water softer.
Similarly, when permanent hard water is treated with washing soda (sodium carbonate), the reaction occurs as follows:
Ca2+ + 2HCO3- + Na2CO3 ⟶ CaCO3 + 2Na+ + 2H2O
In this reaction, the calcium ions (Ca2+) and bicarbonate ions (HCO3-) present in the hard water react with washing soda (sodium carbonate) to form calcium carbonate (CaCO3), sodium ions (Na+), and water (H2O). Again, the calcium carbonate precipitates out of the solution, making the water softer.
Both slaked lime and washing soda act as precipitating agents in the treatment of hard water. The precipitated calcium carbonate can then be filtered or removed, resulting in the removal of hardness from the water.
Verified answer
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When permanent hard water is treated with slaked lime (calcium hydroxide, Ca(OH)2) or washing soda (sodium carbonate, Na2CO3), the hardness causing minerals in the water (usually calcium and magnesium ions) react with these compounds to form insoluble precipitates.
•───────────────────•
1. When treated with slaked lime (calcium hydroxide):
➙The equation for the reaction with calcium hydroxide is as follows:
•───────────────────•
➙Ca(HCO3)2+Ca(OH)2→2CaCO3+2H2O
•───────────────────•
➙The calcium bicarbonate present in the hard water reacts with calcium hydroxide to form insoluble calcium carbonate, which is a white precipitate that settles down as a solid.
The resulting water becomes soft and free from calcium and magnesium ions.
•───────────────────•
2. When treated with washing soda (sodium carbonate):
➙The equation for the reaction with washing soda is as follows:
•───────────────────•
➙Ca(HCO3)2+Na2CO3→CaCO3+2NaHCO3
•───────────────────•
➙Similar to the reaction with slaked lime, the calcium bicarbonate reacts with washing soda to form insoluble calcium carbonate as a white precipitate, along with sodium bicarbonate, which remains dissolved in the water.
The water is now softened and contains sodium bicarbonate.
•───────────────────•
Both slaked lime and washing soda effectively remove the calcium and magnesium ions responsible for the hardness in the water, leading to the formation of insoluble calcium carbonate precipitates that can be separated from the softened water.
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