Water Hardness & Conductivity

Question 1

Water hardness importance

Answer 1

Water is an integral part of food processing

Water that contains excess chemicals can change the flavor and function

Water with excess minerals → clouding

Question 2

Water hardness

Answer 2

Amount of Ca and Mg ions in the water

Question 3

Fouling

Answer 3

Precipitation on processing equipment

Question 4

Water softeners

Answer 4

Remove Ca and Mg from the water in exchange for sodium

Ion exchange system

Question 5

Analysis of minerals

Answer 5

Complexometric titrations
Precipitation titrations
Ion selective electrodes
Atomic absorption spectrometry

Question 6

Atomic absorption spectrometry

Answer 6

Expensive
Tells you every mineral in the water

Question 7

EDTA titration

Answer 7

EDTA forms stable 1:1 complexes w/ mineral ions

Stability of complexes increases with valence

Question 8

EDTA pH

Answer 8

Decreasing the pH → less effective

Chelation sites become protonated (interact w/ H+ not the ions)

pH must be > 10

Question 9

EDTA color change

Answer 9

First the indicator captures the ions
Titrate with EDTA

Excess EDTA forms more stable complexes with the ions (steals them)
Pink –> Blue

Question 10

Water conductivity

Answer 10

measure of the ability of
a substance to conduct electric current

Question 11

Conductivity
cons

Answer 11

Can’t distinguish btwn different ions

Question 12

Water conductivity measurement

Answer 12

Apply an alternating electrical current to two electrodes immersed in a solution and measuring the resulting voltage