Calculating alkalinity and expressing it in "as CaCO3"


by Jim4592
Tags: alkalinity, as caco3, expressing
Jim4592
Jim4592 is offline
#1
Sep20-10, 11:13 PM
P: 49
1. The problem statement, all variables and given/known data
Convert the following from milligrams per liter as the ion to milligrams per liter as CaCO3.

A) 83.00 mg/L Ca2+
B) 27.00 mg/L Mg2+
C) 48.00 mg/L CO2
D) 220.00 mg/L HCO3-
E) 15.00 mg/L CO32-


2. Relevant equations



3. The attempt at a solution
I think I did the calculations correctly, but there's a slight difference between my answer and the book's answer...I was hoping someone could look and see if I did the steps correctly and if so is it difference negligible?

A) (83.00 mg Ca{2+} / L) x (1 mmole Ca{2+} / 40.078 g) x (2 meq Ca{2+} / mmole Ca{2+}) x (100 mg CaCO3 / 2 meq) = 207.096 mg/L as CaCO3, book answer = 207.25

B) (27.00 mg Mg{2+} / L) x (1 mole Mg{2+} / 24.305 g) x (2 meq Mg{2+} / mmole Mg{2+}) x (100 mg CaCO3 / 2 meq) = 111.088 mg/L as CaCO3, book answer = 111.20

C) (48.00 mg CO2 / L) x (1 mmole CO2 / 44.0095 g) x (2 meq CO2 / 1 mmole) x (100 mg CaCO3 / 2 meq) = 109.067 mg/L as CaCO3, book answer = 109.18

D) (220 mg HCO3{-} / L) x (1 mmole HCO3{-} / 61.01684 g) x (1 meq / 1 mmole) x (100 mg CaCO3 / 2 meq) = 180.278 mg/L as CaCO3, book answer = 180.41

E) (15.00 mg CO3 / L) x (1 mmole CO3 / 60.0089 g) x (2 meq / 1 mmole) x (100 mg CaCO3 / 2 meq) = 24.996 mg/L as CaCO3, book answer = 25.02
Phys.Org News Partner Science news on Phys.org
Cougars' diverse diet helped them survive the Pleistocene mass extinction
Cyber risks can cause disruption on scale of 2008 crisis, study says
Mantis shrimp stronger than airplanes
Borek
Borek is offline
#2
Sep21-10, 02:59 AM
Admin
Borek's Avatar
P: 22,708
Obviously book uses slightly different molar masses. I wouldn't care too much, differences are below 10-3, that's about as precise as you can determine alkalinity experimentally.
Jim4592
Jim4592 is offline
#3
Sep22-10, 10:40 AM
P: 49
alright thank's borek, I thought I would be able to just write it off but that's the farthest off we've ever been, so I figured I'd ask for a second opinion.


Register to reply

Related Discussions
Calculating diamter of wire that will "blow" if current exceeds 1A Introductory Physics Homework 2
Calculating Speed of Falling Banana - "Just Before" it Hits Ground? Introductory Physics Homework 2
Calculating "Additional" Braking Torque Due To Momentum Classical Physics 15
Difference between "Identical", "Equal", "Equivalent" Calculus & Beyond Homework 9
Calculating the Capacitance of "out of alignment" finite parallel plate capacitors Introductory Physics Homework 1