Question

A naturally occuring water sample was collected and analyzed to determine its "P" alkalinity. the data below is from trial 1. complete the table for the "P" alkalinity concentration. record the calculated values with the correct number of significiant figures.

1. sample volume (mL)= 50.00

2. buret reading, initial (mL)= 2.05

3. buret reading, final= 20.15

4. volume of HCL added (mL)= ?

molar concenctration of HCL (mol/L)= 0.0148

5. moles of HCL added (mol)=?

6. moles of equivalent CaCO3 (mol)= ?

7. mass CaCO3 (mg)= ?

8. "p" alkalinity, ppm CaCO(s) (mg/L)= ?

Please help, this is for alkalinty of a water resource experiment 20 prelaboratory assignment.

Answer 1

Balanced equation:
CaCO₃(s) + 2 HCl(aq) ===> H₂O(l) + CO₂(g) + CaCl₂(aq)

1. sample volume (mL)= 50.00

2. buret reading, initial (mL)= 2.05

3. buret reading, final= 20.15

4. volume of HCL added (mL)= 20.15 - 2.05 = 18.1 ml

molar concenctration of HCL (mol/L)= 0.0148

5. moles of HCL added (mol)= 18.1 x 0.0148 / 1000 =  0.00026788 Moles

6. moles of equivalent CaCO3 (mol)=  0.00026788 / 2 =  0.00013394 Moles

7. mass CaCO3 (mg)=  0.00013394 x 100.08 = 0.0134 gm

8. "p" alkalinity, ppm CaCO(s) (mg/L)= 0.0134 x 1000 /50 = 0.268 ppm