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100 ml offer sample of water requires 20 ml of N/10 HCl in the presence of a methyl orange indicator .the same water sample on separate titration requires 50 ml of N/10 Na2CO3 for precipitation. What is the hardness of water sample with respect to ppm of CaCO3? The answer is 1500 ppm. Can anyone please explain?
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100 ml offer sample of water requires 20 ml of N/10 HCl in the presenc...
Calculation of Water Hardness
Step 1: Calculation of equivalent weight of CaCO3
- Molecular weight of CaCO3 = 100 g/mol
- CaCO3 contains 2 equivalents of HCl and 1 equivalent of Na2CO3
- Equivalent weight of CaCO3 = 100/2 = 50 g/equivalent
Step 2: Calculation of milliequivalents (meq) of HCl and Na2CO3 used
- N/10 HCl means 1 L of HCl contains 1/10th of equivalent weight of HCl = 5 g/L
- 20 mL of N/10 HCl used = 20/1000 L = 0.02 L
- Milliequivalents of HCl used = 0.02 L x 5 meq/L = 0.1 meq
- N/10 Na2CO3 means 1 L of Na2CO3 contains 1/10th of equivalent weight of Na2CO3 = 10 g/L
- 50 mL of N/10 Na2CO3 used = 50/1000 L = 0.05 L
- Milliequivalents of Na2CO3 used = 0.05 L x 10 meq/L = 0.5 meq
Step 3: Calculation of hardness of water sample
- Hardness of water sample = (milliequivalents of CaCO3/L) x 50 g/equivalent x 10^6 ppm/g
- From step 2, milliequivalents of HCl used = 0.1 meq
- Milliequivalents of Na2CO3 used = 0.5 meq
- Total milliequivalents of CaCO3 in water sample = 0.5 - 0.1 = 0.4 meq
- Volume of water sample used = 100 mL = 0.1 L
- Hardness of water sample = (0.4 meq/L) x (50 g/equivalent) x 10^6 ppm/g = 20000 ppm = 2000 mg/L
Step 4: Conversion of hardness to ppm of CaCO3
- Hardness in mg/L = 2000 mg/L
- Calcium ion (Ca2+) has atomic weight of 40 and CaCO3 contains 1 Ca2+ ion per molecule
- Therefore, 1 mg/L of Ca2+ is equivalent to 25 mg/L of CaCO3
- Hardness in ppm of CaCO3 = 2000 mg/L x 25 = 50000 ppm = 5000 mg/L
Step 5: Correction for divalent cations other than Ca2+
- Assume that the water sample contains equal amounts of Mg2+ ions as Ca2+ ions
- Atomic weight of Mg2+ ion = 24
- Therefore, 1 mg/L of Mg2+ is equivalent to 50 mg/L of CaCO3
- Correction factor = 50/25 = 2
- Corrected hardness in ppm of CaCO3 = 5000 ppm/2 = 2500 ppm
Step 6: Final answer
Step 1: Calculation of equivalent weight of CaCO3
- Molecular weight of CaCO3 = 100 g/mol
- CaCO3 contains 2 equivalents of HCl and 1 equivalent of Na2CO3
- Equivalent weight of CaCO3 = 100/2 = 50 g/equivalent
Step 2: Calculation of milliequivalents (meq) of HCl and Na2CO3 used
- N/10 HCl means 1 L of HCl contains 1/10th of equivalent weight of HCl = 5 g/L
- 20 mL of N/10 HCl used = 20/1000 L = 0.02 L
- Milliequivalents of HCl used = 0.02 L x 5 meq/L = 0.1 meq
- N/10 Na2CO3 means 1 L of Na2CO3 contains 1/10th of equivalent weight of Na2CO3 = 10 g/L
- 50 mL of N/10 Na2CO3 used = 50/1000 L = 0.05 L
- Milliequivalents of Na2CO3 used = 0.05 L x 10 meq/L = 0.5 meq
Step 3: Calculation of hardness of water sample
- Hardness of water sample = (milliequivalents of CaCO3/L) x 50 g/equivalent x 10^6 ppm/g
- From step 2, milliequivalents of HCl used = 0.1 meq
- Milliequivalents of Na2CO3 used = 0.5 meq
- Total milliequivalents of CaCO3 in water sample = 0.5 - 0.1 = 0.4 meq
- Volume of water sample used = 100 mL = 0.1 L
- Hardness of water sample = (0.4 meq/L) x (50 g/equivalent) x 10^6 ppm/g = 20000 ppm = 2000 mg/L
Step 4: Conversion of hardness to ppm of CaCO3
- Hardness in mg/L = 2000 mg/L
- Calcium ion (Ca2+) has atomic weight of 40 and CaCO3 contains 1 Ca2+ ion per molecule
- Therefore, 1 mg/L of Ca2+ is equivalent to 25 mg/L of CaCO3
- Hardness in ppm of CaCO3 = 2000 mg/L x 25 = 50000 ppm = 5000 mg/L
Step 5: Correction for divalent cations other than Ca2+
- Assume that the water sample contains equal amounts of Mg2+ ions as Ca2+ ions
- Atomic weight of Mg2+ ion = 24
- Therefore, 1 mg/L of Mg2+ is equivalent to 50 mg/L of CaCO3
- Correction factor = 50/25 = 2
- Corrected hardness in ppm of CaCO3 = 5000 ppm/2 = 2500 ppm
Step 6: Final answer
Community Answer
100 ml offer sample of water requires 20 ml of N/10 HCl in the presenc...
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100 ml offer sample of water requires 20 ml of N/10 HCl in the presence of a methyl orange indicator .the same water sample on separate titration requires 50 ml of N/10 Na2CO3 for precipitation. What is the hardness of water sample with respect to ppm of CaCO3? The answer is 1500 ppm. Can anyone please explain?
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100 ml offer sample of water requires 20 ml of N/10 HCl in the presence of a methyl orange indicator .the same water sample on separate titration requires 50 ml of N/10 Na2CO3 for precipitation. What is the hardness of water sample with respect to ppm of CaCO3? The answer is 1500 ppm. Can anyone please explain? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about 100 ml offer sample of water requires 20 ml of N/10 HCl in the presence of a methyl orange indicator .the same water sample on separate titration requires 50 ml of N/10 Na2CO3 for precipitation. What is the hardness of water sample with respect to ppm of CaCO3? The answer is 1500 ppm. Can anyone please explain? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for 100 ml offer sample of water requires 20 ml of N/10 HCl in the presence of a methyl orange indicator .the same water sample on separate titration requires 50 ml of N/10 Na2CO3 for precipitation. What is the hardness of water sample with respect to ppm of CaCO3? The answer is 1500 ppm. Can anyone please explain?.
100 ml offer sample of water requires 20 ml of N/10 HCl in the presence of a methyl orange indicator .the same water sample on separate titration requires 50 ml of N/10 Na2CO3 for precipitation. What is the hardness of water sample with respect to ppm of CaCO3? The answer is 1500 ppm. Can anyone please explain? for NEET 2024 is part of NEET preparation. The Question and answers have been prepared according to the NEET exam syllabus. Information about 100 ml offer sample of water requires 20 ml of N/10 HCl in the presence of a methyl orange indicator .the same water sample on separate titration requires 50 ml of N/10 Na2CO3 for precipitation. What is the hardness of water sample with respect to ppm of CaCO3? The answer is 1500 ppm. Can anyone please explain? covers all topics & solutions for NEET 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for 100 ml offer sample of water requires 20 ml of N/10 HCl in the presence of a methyl orange indicator .the same water sample on separate titration requires 50 ml of N/10 Na2CO3 for precipitation. What is the hardness of water sample with respect to ppm of CaCO3? The answer is 1500 ppm. Can anyone please explain?.
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