# Chapter 7:Water Chemistry¶

## Example no:1,Page no:152¶

In [1]:
#Variable declaration
MgSO4=60.0          #[mg]
M_MgSO4=64.0        #Molecular weight of MgSO4
M_CaCO3=48.0        #Molecular wt of CaCO3
m_mgso4=120.0       #Weight of MgSO4 eq to CaCO3
m_caco3=100.0       #Weight of CaCO3 eq to MgSO4

#Calculation
hard=(m_caco3/m_mgso4)*MgSO4      #Hardness of water in mg

#Result
print"Hardness of water is ",hard,"ppm"

Hardness of water is  50.0 ppm


## Example no:7.1,Page no:172¶

In [2]:
#Variable declaration
W1=16.2 #Ca(HCO3)2 in water in mg/lit#
W2=7.3 #MgHCO3 in water in mg/lit#
W3=13.6 #CaSO4 in water in mg/lit#
W4=9.5 #MgCl2 in water in mg/lit#
M1=100/162.0 #multiplication factor of Ca(HCO3)2#
M2=100/146.0 #multiplication factor of MgHCO3#
M3=100/136.0 #multiplication factor of CaSO4#
M4=100/95.0 #multiplication factor of MgCl2#

#Calculation
P1=W1*M1 #Ca(HCO3)2 in terms of CaCO3 or #
P2=W2*M2 #MgHCO3 in terms of CaCO3 or #
P3=W3*M3 #CaSO4  in terms of CaCO3 or #
P4=W4*M4 #MgCl2 in terms of CaCO3 or #
T=P1+P2    #Temporary hardness
P=P3+P4     #Permanent hardness
To=T+P     #Total hardness

#Result
print"Temporary hardness is",T,"mg/l or ppm"
print"\nPermanant hardness is ",P,"mg/l or ppm"
print"\nTotal hardness is ",To,"mg/l or ppm"

Temporary hardness is 15.0 mg/l or ppm

Permanant hardness is  20.0 mg/l or ppm

Total hardness is  35.0 mg/l or ppm


## Example no:7.2,Page no:172¶

In [3]:
#Variable declaration
F=56.0 #atomic weight of ferrus#
S=32.0 #atomic weight of sulphur#
O=16.0 #atomic weight of oxygen#
Ca=40.0 #atomic weight of calsium#
C=12.0 #atomic weight of carbon#

#Calculation
W1=136
P=210.5 #required ppm of hardness#
B=(W1/100.0)*P

#Result
print"Required FeSO4 for 100ppm of hardness is",W1,"ppm pf FeSO4"
print"\nRequired FeSO4 for 210.5ppm of hardness is ",round(B,1),"ppm of FeSO4"

Required FeSO4 for 100ppm of hardness is 136 ppm pf FeSO4

Required FeSO4 for 210.5ppm of hardness is  286.3 ppm of FeSO4


## Example no:7.3,Page no:173¶

In [4]:
#Variable declaration
W1=162.0 #Ca(HCO3)2 in water in mg/lit#
W2=73.0 #MgHCO3 in water in mg/lit#
W3=136.0 #CaSO4 in water in mg/lit#
W4=95.0 #MgCl2 in water in mg/lit#
W5=111.0 #CaCl2 in water in mg/lit#
W6=100.0 #NaCl in water in mg/lit#
M1=100/162.0 #multiplication factor of Ca(HCO3)2#
M2=100/146.0 #multiplication factor of MgHCO3#
M3=100/136.0 #multiplication factor of CaSO4#
M4=100/95.0 #multiplication factor of MgCl2#
M5=100/111.0 #multiplication factor of CaCl2#
M6=100/100.0 #multiplication factor of NaCl#

#Calculation
P1=W1*M1 #Ca(HCO3)2 in terms of CaCO3 or #
P2=W2*M2 #MgHCO3 in terms of CaCO3 or #
P3=W3*M3 #CaSO4  in terms of CaCO3 or #
P4=W4*M4 #MgCl2 in terms of CaCO3 or #
P5=W5*M5 #CaCl2 in terms of CaCO3 or #
T=P1+P2
P=P3+P4+P5

#Result
print"\nTemporary hardness is",T,"mg/l or ppm"
print"\nPermanant hardness is",P,"mg/l or ppm"

Temporary hardness is 150.0 mg/l or ppm

Permanant hardness is 300.0 mg/l or ppm


## Example no:7.4,Page no:173¶

In [5]:
#Variable declaration
N=0.08 #normality of MgSO4#
V1=12.5 #volume of MgSO4 in ml#
V2=100 #volume of water sample#

#Calculation
M=N/2 #molarity of MgSO4#
N1=(M*12.5)/1000 #no of moles of MgSO4 in 100 ml water#
N2=(N1*1000)/100 #no of moles of MgSO4 in one litre water#
W=100 #molecular weight of CaCO3
W1=N2*W*1000 #MgSO4 in terms of CaCO3 in mg/lit#

#Result
print"\nThe hardness due to MgSO4 is ",W1,"mg/l CaCO3 or ppm of CaCO3"

The hardness due to MgSO4 is  500.0 mg/l CaCO3 or ppm of CaCO3


## Example no:7.5,Page no:173¶

In [6]:
#Variable declaration
W1=144.0 #MgCO3 in water in mg/lit#
W2=25.0 #CaCO3 in water in mg/lit#
W3=111.0 #CaCl2 in water in mg/lit#
W4=95.0 #MgCl2 in water in mg/lit#
M1=100/84.0 #multiplication factor of MgCO3#
M2=100/100.0 #multiplication factor of CaCO3#
M3=100/111.0 #multiplication factor of CaCl2#
M4=100/95.0 #multiplication factor of MgCl2#

#Calculation
P1=W1*M1 #MgCO3 in terms of CaCO3 or ppm#
P2=W2*M2 #CaCO3 in terms of CaCO3 or ppm#
P3=W3*M3 #CaCl2  in terms of CaCO3 or ppm#
P4=W4*M4 #MgCl2 in terms of CaCO3 or ppm#
V=50000 #volume of water in lit#
L=0.74*(2*P1+P2+P4)*V
S=1.06*(P1+P3+P4)*V

#Result
print"Requirement of lime is ",L,"mg=",round(L/1000000,1),"kg"
print"\nRequirement of soda is ",S,"mg=",round(S/1000000,1),"kg"

Requirement of lime is  17310714.2857 mg= 17.3 kg

Requirement of soda is  19685714.2857 mg= 19.7 kg


## Example no:7.6,Page no:174¶

In [7]:
#Variable declaration
W1=12.0 #Mg2+ in water in ppm or mg/l#
W2=40.0 #Ca2+ in water in ppm or mg/l#
W3=164.7 #HCO3- in water in ppm or mg/l#
W4=30.8 #CO2 in water in ppm or mg/l#
M1=100.0/24.0 #multiplication factor of Mg2+#
M2=100.0/40.0 #multiplication factor of Mg2+#
M3=100.0/61.0 #multiplication factor of Mg2+#
M4=100.0/44.0 #multiplication factor of Mg2+#

#Calculation
P1=W1*M1 # in terms of CaCO3#
P2=W2*M2 # in terms of CaCO3#
P3=W3*M3/2 # in terms of CaCO3#
P4=W4*M4 # in terms of CaCO3#
V=50000.0#volume of water in lit#
L=0.74*(P1+P3+P4)*V

#Result
print"Lime required is %fmg",round(L/10**6,1),"kg"

Lime required is %fmg 9.4 kg


## Example no:7.7,Page no:174¶

In [8]:
#Variable declaration
W1=160.0 #Ca2+ in water in mg/l or ppm#
W2=72.0 #Mg2+ in water in mg/l or ppm#
W3=732.0 #HCO3- in water in mg/l or ppm#
W4=44.0 #CO2 in water in mg/l or ppm#
W5=16.4 #NaAlO2 in water in mg/l or ppm#
W6=30.0 #(CO3)2- in water in mg/l or ppm#
W7=17.0 #OH- in water in mg/l or ppm#

#Calculation
M1=100/40.0 #multiplication factor of Ca2+#
M2=100/24.0 #multiplication factor of Ca2+#
M3=100/(61.0*2.0) #multiplication factor of Ca2+#
M4=100/44.0 #multiplication factor of Ca2+#
M5=100/(82.0*2.0) #multiplication factor of Ca2+#
M6=100/60.0 #multiplication factor of Ca2+#
M7=100/(17.0*2.0) #multiplication factor of Ca2+#
P1=W1*M1 #in terms of CaCO3#
P2=W2*M2 #in terms of CaCO3#
P3=W3*M3 #in terms of CaCO3#
P4=W4*M4 #in terms of CaCO3#
P5=W5*M5 #in terms of CaCO3#
P6=W6*M6 #in terms of CaCO3#
P7=W7*M7 #in terms of CaCO3#
V=200000.0 #volume of water in lit#
L=0.74*(P2+P3+P4-P5+P7)*V
L=L/10.0**6.0 #in kgs#
S=1.06*(P1+P2-P3-P5-P6+P7)*V
S=S/10.0**6 #in kgs#

#Result
print"Lime required is ",L,"kg"
print"\nSoda required is ",S,"kg"

Lime required is  153.92 kg

Soda required is  19.08 kg


## Example no:7.8,Page no:175¶

In [9]:
#Variable declaration
N=150.0 #amount of NaCl in solution in g/l#
V=8.0 #volume of NaCl solution#

#Calculation
M=N*V
V=10000.0 #volume of hard water#
W=58.5 #molecular weight of NaCl#
K=(M*100.0/(W*2))/V
J=K*1000.0

#Result

print"\nHardness of water is ",round(J,1),"mg/l or ppm"

Hardness of water is  102.6 mg/l or ppm


## Example no:7.9,Page no:176¶

In [10]:
#Variable declaration
W1=219.0 #amount of Mg(HCO3)2 in water in ppm#
W2=36.0 #amount of Mg2+ in water in ppm#
W3=18.3 #amount of (HCO3)- in water in ppm#
W4=1.5 #amount of H+_in water in ppm#
M1=100/146.0 #multiplication factor of Mg(HCO3)2#
M2=100/24.0 #multiplication factor of Mg(HCO3)2#
M3=100/122.0 #multiplication factor of Mg(HCO3)2#
M4=100/2.0 #multiplication factor of Mg(HCO3)2#

#Calculation
P1=W1*M1 #in terms of CaCO3#
P2=W2*M2 #in terms of CaCO3#
P3=W3*M3 #in terms of CaCO3#
P4=W4*M4 #in terms of CaCO3#
L=0.74*((2*P1)+P2+P3+P4)

R=1.0 #water supply rate in m**3/s#
D=R*60.0*60.0*24.0*L
K=D*1000.0 #in lit/day#
T=K/10.0**9 #in tonnes#
S=1.06*(P2+P4-P3)
D2=R*60*60*24*S
A=D2*1000 #in lit/day#
B=A/10.0**9 #in tonnes#
J1=90/100.0 #purity of lime#
J2=95/100.0 #purity of soda#
C1=500.0 #cost of one tonne lime#
C2=7000.0 #cost of one tonne soda#
CL=round(T,1)*C1/J1
print"\ncost of lime is",CL,"Rs"
CS=round(B,1)*C2/J2
print"\ncost of soda is ",CS,"Rs"
C=CL+CS

#Result
print"\ntotal cost is ",round(C) ,"Rs"

cost of lime is 19166.6666667 Rs

cost of soda is  141473.684211 Rs

total cost is  160640.0 Rs


## Example no:7.10,Page no:176¶

In [11]:
#Variable declaration
W1=40.0 #amount of Ca2+ in water in mg/l#
W2=24.0 #amount of Mg2+ in water in mg/l#
W3=8.05 #amount of Na+ in water in mg/l#
W4=183.0 #amount of (HCO3)- in water in mg/l#
W5=55.68 #amount of (SO4)2- in water in mg/l#
W6=6.74 #amount of Cl- in water in mg/l#
M1=100/40.0 #multiplication factor of Ca2+#
M2=100/24.0 #multiplication factor of Mg2+#
M3=100/(23.0*2) #multiplication factor of Na+#
M4=100/(61.0*2) #multiplication factor of (HCO3)-#
M5=100/96.0 #multiplication factor of (SO4)2-#
M6=100/(35.5*2) #multiplication factor of Cl-#

#Calculation
P1=W1*M1 #in terms of CaCO3#
P2=W2*M2 #in terms of CaCO3#
P3=W3*M3 #in terms of CaCO3#
P4=W4*M4 #in terms of CaCO3#
P5=W5*M5 #in terms of CaCO3#
P6=W6*M6 #in terms of CaCO3#

#Result
print"\nCalcium alkalinity =",P1,"ppm"
print"\nMagnesium alkalinity =",P4-P1,"ppm"
print"\n  total alkalinity = ",P1+P4-P1,"ppm"
print"\n  total hardness = ",P1+P2,"ppm"
print"\nCa temporary hardness = ",P1,"ppm"
print"\nMg temporary hardness = ",P4-P1,"ppm"
print"\nMg permanant hardness = ",P2-(P4-P1),"ppm"
print"\nSalts are:"
print"\nCa(HCO3)2 salt = ",P1,"ppm"
print"\nMg(HCO3)2 salt = ",P4-P1,"ppm"
print"\nMgSO4 salt = ",P2-(P4-P1),"ppm"
print"\nNaCl salt = ",P6,"ppm"

Calcium alkalinity = 100.0 ppm

Magnesium alkalinity = 50.0 ppm

total alkalinity =  150.0 ppm

total hardness =  200.0 ppm

Ca temporary hardness =  100.0 ppm

Mg temporary hardness =  50.0 ppm

Mg permanant hardness =  50.0 ppm

Salts are:

Ca(HCO3)2 salt =  100.0 ppm

Mg(HCO3)2 salt =  50.0 ppm

MgSO4 salt =  50.0 ppm

NaCl salt =  9.49295774648 ppm


## Example no:7.11,Page no:177¶

In [12]:
#Variable declaration
P=0.0 #phenolplthalein alkalinity in water sample#
V=16.9 #required HCl in ml for 100 ml water sample#
N=0.02 #normality of HCl#
print"Since P=0 the alkalinity is due to HCO3- ions"
C=50.0 #equivalent of CaCO3 in mg for 1 ml 1N of HCl#

#Calculation
A=C*V*N
print"\nIn 100ml water sample the alkalinity is",A,"mg/s"
B=A*1000.0/100.0

#Result
print"\nFor 1 litre of water the alkalinity is ",B,"mg/l"

Since P=0 the alkalinity is due to HCO3- ions

In 100ml water sample the alkalinity is 16.9 mg/s

For 1 litre of water the alkalinity is  169.0 mg/l


## Example no:7.12,Page no:178¶

In [13]:
#Variable declaration
P=4.7 #required HCl in ml using HpH indicator #
H=10.5 #required HCl im ml using MeOH indicator#
M=P+H
N=0.02 #normality of HCl#

print"\nSince P<0.5*M sample contain (CO3)2- and (HCO3)- alkalinity"
C=50 #equivalent of CaCO3 in mg for 1ml 1N HCl#

#Calculation
A=C*(2*P)*N #amount of (CO3)2- alkalinity in mg in 100 ml of water#
B=A*1000/100
D=C*(M-2*P)*N #the amount of (HCO3)- alkalinity in mg in 100 ml of water#
E=D*1000/100
T=B+E

#Result
print"\nTotal alkalinity is ",T,"mg/l or ppm"

Since P<0.5*M sample contain (CO3)2- and (HCO3)- alkalinity

Total alkalinity is  152.0 mg/l or ppm


## Example no:7.13,Page no:178¶

In [14]:
#Variable declaration
W1=160.0 #amount of Ca2+ in ppm#
W2=88.0 #amount of Mg2+ in ppm#
W3=72.0 #amount of CO2 in ppm#
W4=488.0 #amount of (HCO3)- in ppm#
W5=139.0 #amount of (FeSO4).7H2O in ppm#
M1=100/40.0 #multiplication factor of Ca2+#
M2=100/24.0 #multiplication factor of Mg2+#
M3=100/44.0 #multiplication factor of CO2#
M4=100/(61.0*2.0) #multiplication factor of (HCO3)-#
M5=100/278.0 #multiplication factor of (FeSO4).7H2O#

P1=400 #in terms of CaCO3#
P2=300 #in terms of CaCO3#
P3=200 #in terms of CaCO3#
P4=400 #in terms of CaCO3#
P5=50 #in terms of CaCO3#
V=100000.0 #volume of water in litres#

#Calculation
L=0.74*(P2+P3+P4+P5)*V #lime required in mg#
L=L/10.0**6
S=1.06*(P1+P2+P5-P4)*V #soda required in mg#
S=S/10.0**6

#Result
print"Lime required is ",L,"kg"
print"\nSoda required is ",S,"kg"

Lime required is  70.3 kg

Soda required is  37.1 kg


## Example no:7.14,Page no:179¶

In [15]:
#Variable declaration
W=50 #amount of NaCl in g/l in NaCl solution#
V=200 #volume of NaCl solution in litres#

#Calculation
A=W*V
V=10000 #volume of hard water passed through Zeolite softener#
M=100/(58.5*2) #multiplication factor of NaCl#
P=M*A
B=P*1000/V

#Result
print"\nIn terms of CaCO3=",round(P),"g CaCO3"
print"\nFor 1 litre of hard water=",round(B,1),"mg/l or ppm"
print"NOTE:In book answer wrongly written as 845.7"

In terms of CaCO3= 8547.0 g CaCO3

For 1 litre of hard water= 854.7 mg/l or ppm
NOTE:In book answer wrongly written as 845.7


## Example no:7.15,Page no:179¶

In [16]:
#Variable declaration
W1=0.28 #amount of CaCO3 in grams dissolved in 1 litre of water#
V1=28 #required EDTA in ml on titration of 100ml of CaCO3 solution#
V2=33 #required EDTA in ml for 100ml of unknown hard water sample#
V3=10 #required EDTA in ml for 100 ml of unknown sample after boiling and cooling#
M1=100/100 #multiplication factor of CaCO3#

#Calculation
C=W1*M1
A=C*100#for 100 ml of sample equivalent to 28 ml of EDTA#
B=A/V1
D=V2*B #for 100 ml#
D=D*1000/100
E=V3*B #for 100 ml#
E=E*1000/100
T=D-E

#Result
print"Total hardness is ",D,"mg CaCO3 eq"
print"\nPermanant hardness is ",E,"mg CaCO3 eq"
print"\nTemporary hardness is ",T,"mg CaCO3"

Total hardness is  330.0 mg CaCO3 eq

Permanant hardness is  100.0 mg CaCO3 eq

Temporary hardness is  230.0 mg CaCO3