Question

Calculating the Water Hardness For convenience, assume that all hardness is due to the presence of only Ca$^{2+}$ ions, in the form of calcium carbonate, CaCO$_3$. The unit of hardness may be expressed in terms of molarity of CaCO$_3$, but is usually expressed as mg CaCO$_3$ per liter of water, which is equivalent to parts per million CaCO$_3$ (ppm CaCO$_3$). The hardness equals molarity Ca$^{2+}$ = frac{mmol Ca$^{2+}$ ion}{mL} = frac{(Molarity of EDTA)(mL EDTA added)}{50.00 mL of water sample} Since ppm CaCO$_3$ = # mg CaCO$_3$/L, ppm CaCO$_3$ = (Molarity Ca$^{2+}$) imes frac{1 mol CaCO$_3$}{1 mol Ca$^{2+}$} imes frac{100.1 g CaCO$_3$}{1 mol CaCO$_3$} imes frac{10^3 mg}{1 g}

          Calculating the Water Hardness
For convenience, assume that all hardness is due to the presence of only Ca$^{2+}$ ions, in the form of
calcium carbonate, CaCO$_3$. The unit of hardness may be expressed in terms of molarity of CaCO$_3$,
but is usually expressed as mg CaCO$_3$ per liter of water, which is equivalent to parts per million
CaCO$_3$ (ppm CaCO$_3$).
The hardness equals
molarity Ca$^{2+}$ = frac{mmol Ca$^{2+}$ ion}{mL} = frac{(Molarity of EDTA)(mL EDTA added)}{50.00 mL of water sample}
Since ppm CaCO$_3$ = # mg CaCO$_3$/L,
ppm CaCO$_3$ = (Molarity Ca$^{2+}$) 	imes frac{1 mol CaCO$_3$}{1 mol Ca$^{2+}$} 	imes frac{100.1 g CaCO$_3$}{1 mol CaCO$_3$} 	imes frac{10^3 mg}{1 g}

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$Calculating the Water Hardness For convenience, assume that all hardness is due to the presence of only Ca^2+ ions, in the form of calcium carbonate, CaCO3. The unit of hardness may be expressed in terms of molarity of CaCO3, but is usually expressed as mg CaCO3 per liter of water, which is equivalent to parts per million CaCO3 (ppm CaCO3). The hardness equals molarity Ca^2+ = fracmmol Ca^2+ ionmL = frac(Molarity of EDTA)(mL EDTA added)50.00 mL of water sample Since ppm CaCO3 = # mg CaCO3/L, ppm CaCO3 = (Molarity Ca^2+) imes frac1 mol CaCO31 mol Ca^2+ imes frac100.1 g CaCO31 mol CaCO3 imes frac10^3 mg1 g$

Added by Peter S.

Chemistry: Structure and Properties

Nivaldo Tro 2nd Edition

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Solved by Expert Shyam P

04/21/2022

Step 1

First, we need to calculate the molarity of Ca2+ ions in the water sample. This can be done by dividing the number of millimoles of Ca2+ ions by the volume of the water sample in liters. Show more…

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Calculating the Water Hardness For convenience, assume that all hardness is due to the presence of only Ca2+ ions in the form of calcium carbonate, CaCO3. The unit of hardness may be expressed in terms of molarity of CaCO3, but is usually expressed as mg CaCO3 per liter of water, which is equivalent to parts per million CaCO3 (ppm CaCO3). The hardness equals: molarity Ca2+ = mmol Ca2+ ion / mL = (Molarity of EDTA)(mL EDTA added) / 50.00 mL of water sample Since ppm CaCO3 = # mg CaCO3/L; ppm CaCO3 = (Molarity Ca2+) x (1 mol CaCO3 / 1 mol Ca2+) x (100.1 g CaCO3 / 1 mol CaCO3) x (10^3 mg / 1 g)

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Transcript

00:01 So this question is related to the hardness of water.

00:05 So this hardness of water it is decided by the calcium and the magnesium ion present in that water.

00:15 So here we have the standardization of the addita.

00:21 Adeta is ethylene, diamine, tetraicate.

00:28 So here the concentration of the ca plus two, solosylase, and then.

00:34 It is 0 .0100m that is the value of the c1.

00:43 And the volume of this and the volume of ca plus 2 it is 25 ml that is v1 and the volume of the editor that is used it is 16 .13m.

01:04 That is v2 so so, now this is the average value and hence we can find out the molarity of editor or the concentration of editor.

01:27 So we know the formula that is m1 v1 is equal to m2 v2 and hence we need to find out the value of the m2 or we can just write it as in the form of c1 v1 is equal to c2 v2.

01:46 That is we need to find out the value of the c2.

01:49 So c2 can be written as c1 v1 divided by v2 and it is equal to c1 it is 0 .01 multiplied by 25 divided by 16 .13.

02:01 And hence the value of the c2 or the molarity of the addita will be 0 .0155m.

02:10 So now let us calculate the hardness of the water.

02:13 So the volume of editor that is used, average it is given here, 1 .367 ml, and the molarity of, molarity of ca plus 2, it is equal to the molarity of editor multiply by ml of editor, or we can say the volume of addita which is used...

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