Question

A water has a pH of 8.00 and the concentration of HCO3- is 193.00 mg/L. What...

A water has a pH of 8.00 and the concentration of HCO3- is 193.00 mg/L. What is the alkalinity of the water in unit of mg/L as CaCO3? (Note: The pKa for H2CO3/HCO3- is 6.3. The pKa for HCO3-/CO32- is 10.33. The pKa for the dissociation of water to H+ and OH- is 14.0. The temperature is 25oC

Homework Answers

Answer #1

Alkalinity is calculated as

Alkalinity=[CO32-]+[HCO3-]+[OH-]+[H+]

Given pH=8 so pOH=14-8=6

[H+]=10-8 and [OH-]=10-6

Given [HCO3-]=193mg/L

Using pKa for  H2CO3/HCO3- is 6.3

Using Henderson equation

pH=pKa+log(HCO3/H2CO3/)

we get [H2CO3]=3.85mg/l

Similarly for calculationg [CO32-]

pH=10.33+log(CO32-/HCO3-)

we get [CO32-]=0.9mg/l

So alkalinity=10-8+10-6+0.9+3.85+193=197.75 mg/l

in terms of unit mg/L as CaCO3=

Bicarbonate Alkalinity as HCO3 - (mg/L) = 1.22 *Bicarbonate Alkalinity as CaCO3 (mg/L)

Carbonate Alkalinity as CO3 2- (mg/L) = 0.6 *Carbonate Alkalinity as CaCO3 (mg/L)

Hydroxide Alkalinity as OH- (mg/L) = 0.34*Hydroxide Alkalinity as CaCO3 (mg/L)

Bicarbonate Alkalinity as CaCO3 (mg/L)=193/1.22=158.2 mg/l

Carbonate Alkalinity as CaCO3 (mg/L)=0.9/0.6=1.5mg/l

Due to OH- H+ and H2CO3 it will be negligible

So Tatal Alkalinity=158.2=1.5=159.7mg/l of CaCO3

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
The alkalinity of a water consists of 12 mg/L of CO32- and 100 mg/L HCO3-. Calculate...
The alkalinity of a water consists of 12 mg/L of CO32- and 100 mg/L HCO3-. Calculate the alkalinity in mg/L as CaCO3 by Ignoring [OH-] and [H+].
A water sample has an alkalinity of 135 mg/L as CaCO3 and a pH of 8.8....
A water sample has an alkalinity of 135 mg/L as CaCO3 and a pH of 8.8. Determine the concentrations [mg/L] of HCO3-, CO3-2 and OH-.
A water has an alkalinity of 200 mg/L as CaCO3. The Ca2+ concentration is 160 mg/L...
A water has an alkalinity of 200 mg/L as CaCO3. The Ca2+ concentration is 160 mg/L as the ion and the Mg2+ concentration is 40 mg/L as the ion. The pH is 8.1. Find the total carbonate and noncarbonate hardness
100 million gallon per day of water of pH 8 and alkalinity (HCO3-) of 200 mg/L...
100 million gallon per day of water of pH 8 and alkalinity (HCO3-) of 200 mg/L as CaCO3. If it is required to lower the pH from 8 to 7 by using 1 g/L of HCl stock solution, then how much HCl is required (gallon/day) while considering the above mentioned alkalinity?
A water sample has a pH of 8.21 and a total Ca2+ concentration of 143 ppm....
A water sample has a pH of 8.21 and a total Ca2+ concentration of 143 ppm. a)What are the molar concentrations of CO32− and HCO3−? b)What is the total alkalinity of the water?
A water sample has a pH of 8.21 and a total Ca2+ concentration of 143 ppm....
A water sample has a pH of 8.21 and a total Ca2+ concentration of 143 ppm. a)What are the molar concentrations of CO32− and HCO3−? b)What is the total alkalinity of the water?
A groundwater contains magnesium at a concentration of 182.0 mg/L as CaCO3. The magnesium is to...
A groundwater contains magnesium at a concentration of 182.0 mg/L as CaCO3. The magnesium is to be removed by precipitation as Mg(OH)2. What must the pH be in order to attain a final magnesium concentration of 6.0 mg/L as CaCO3? Note: Mg(OH)2 = Mg2+ + 2OH-, pKs = 11.25
A groundwater contains magnesium at a concentration of 98.0 mg/L as CaCO3. The magnesium is to...
A groundwater contains magnesium at a concentration of 98.0 mg/L as CaCO3. The magnesium is to be removed by precipitation as Mg(OH)2. What must the pH be in order to attain a final magnesium concentration of 5.0 mg/L as CaCO3? Note: Mg(OH)2 = Mg2+ + 2OH-, pKs = 11.25.
You have a water sample with an alkalinity of 2.3 x 10-3 eq/L and a pH...
You have a water sample with an alkalinity of 2.3 x 10-3 eq/L and a pH of 8.10. Assume that the inorganic carbon species are the main contributors to alkalinity (true in most natural water systems). Calculate the [H2CO3*], [HCO3 - ] [CO3 2- ] and [OH- ] concentrations
100 mg of H2CO3 are dissolved in 700 mL of water. A lab assistant measured the...
100 mg of H2CO3 are dissolved in 700 mL of water. A lab assistant measured the resulting pH= 4.9. Determine the molar concentration of H2CO3, HCO3- and CO32-in the solution.
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT