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Carbonate Hardness Test Strips 70-425 ppm EM Quant (1 PK of 100)

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Carbonate Hardness Test Strips 70-425 ppm EM Quant (1 PK of 100) MAIN

EM Quant® Carbonate Hardness Test Strips, 70-425 ppm, 1.10648.0001

Additional Production Information
Method: Color scale
Color Reaction: Carbonate and hydrogen carbonate ions react with acid. The resultant pH value produces an effect on the color of a mixed indicator.
Graduation: 4-8-12-16-24°d
Determinations: 100
Storage Conditions: +15 to +25°C
Shelf Life: 36 months (from day of production)

EM Quant® Carbonate Hardness Test, Part# 1.10648.0001

Test strips for the detection and semi-quantitative determination of "hardness" ions

1. Definition
Carbonate hardness is defined as that portion of all calcium ions (Ca2+) and magnesium ions (Mg2+) ("hardness ions," "hardening constituents") present in 1 liter of water for which there exists an equivalent amount of hydrogen carbonate ions (HCO3–) and carbonate ions (CO32–) originating from dissolved carbonic acid.

The so-called "German degree" is frequently used as a practical measurement unit for hardness; this degree is defined as follows: 1°d = 10mg/l CaO

The ratio of HCO3- to CO32– is dependent on the pH value. Most natural waters (pH <8) contain almost exclusively HCO3– ions.
The carbonates and hydrogen carbonates of the hardening constituents precipitate as carbonates under heat; for this reason, carbonate hardness was once also termed "temporary hardness."
2. Method
Carbonate and hydrogen carbonate ions react with acid. The resultant pH value produces an effect on the color of a mixed indicator. Carbonate hardness is measured semiquantitatively by visual comparison of the reaction zone of the test strip with the fields of a color scale.

3. Measuring Range and Number of Determinations
Measuring Range/Color Scale Graduation1 Number of Determinations
4-8-12-16-24°d 100

1 for conversion factors, see Section 8

4. Applications
Sample material:
Drinking water, mineral water and curative water
Spring water and well water
Industrial water
Boiler water and boiler feed water
Cooling water
Aquarium water

5. Influence of Foreign Substances
The determination is interfered with when the water sample contains--in addition to the salts of carbonic acid--strong bases or other acid consuming substances such as phosphates and polyphosphates. Flocculating agents that bind carbonate and hydrogen carbonate ions produce a false-low carbonate-hardness result.

6. Reagents and Auxiliaries
The analytical test strips are stable at least up to the date stated on the pack when stored in the closed tube at +15 to +25°C.

Package contents: Tube containing 100 analytical test strips.

Also recommended: EM Quant® Total Hardness Test, Cat. No. 10025.

Measuring range <3 - >21°d (<4 - >26°e)

7. Procedure
Remove 1 analytical test strip and immediately reclose the tube.
Immerse the reaction zone of the test strip in the measurement solution for 1 second.
Shake off excess liquid from the test strip.
After 1 minute compare the color of the reaction zone with the color fields on the label. Determine with which field the color of the reaction zone coincides most exactly and read off the corresponding concentration value. If an exact color match cannot be achieved, estimate an intermediate value.

It is recommended to always determine the total hardness in addition to the carbonate hardness. This is because in some cases due to ion-exchange processes, a portion of the hardness ions in the ground is replaced by other metal ions, with the result that the water sample contains more equivalents of hydrogen carbonate and carbonate ions than of calcium and magnesium ions. If the value found in the Carbonate Hardness is accordingly higher than that found in the Total Hardness Test, carbonate hardness must be set equal to total hardness.

· The color of the reaction zone may continue to change after the specified reaction time has elapsed. This must not be considered in the measurement.

Given mmol/l
+ Mg2+ German Degree
°d English Degree
°e French Degree
°f mg/l (ppm)
1 mmol/l
Ca2+ + Mg2+ 1 5.60 7.02 10.00 100.0
1 German Degree (°d) 0.18 1 1.25 1.78 17.8
1 English Degree (°e) 0.14 0.799 1 1.43 14.3
1 French Degree (°f) 0.10 0.560 0.700 1 10.0
1mg/l (ppm)
CaCO3 0.01 0.056 0.070 0.10 1

Of the units given in the above table, only "mmol/l" is internationally accepted (Sl unit). Water hardness must therefore, officially be stated in terms of the concentration of the hardness ions Ca22+ + Mg2+ in mmol/l. Since the hydrogen carbonate and the carbonate ions present in water are capable of binding acid (H+ ions), carbonate hardness can also be interpreted as acid-binding capacity (ABC). With regard to the ions of carbonic acid, the acid-binding capacity becomes exhausted at pH 4.3; in other words all carbonate and hydrogen carbonate ions have taken up H+ ions at this pH level, and only dissolved carbonic acid is present. (For this reason, it is also usual to speak of "acid binding capacity up to pH 4.3".)

Since the acid-binding capacity is determined by titration with hydrochloric acid (i.e. addition of monovalent H+ ions, yet carbonate hardness is defined as the concentration of bivalent ions, the following formula applies:

Carbonate hardness [mmol/l hardness ions] x 2 = ABC [mmol/l]

The conversion table shows that

Carbonate hardness [°e] = carbonate hardness [mmol/l hardness ions] x 7.02

which results in

Carbonate hardness [°e]
3.51 = ABC [mmol/l]

Package Size

10648 EM Quant® Test strips

Carbonate Hardness Test for 100 determinations

MSDS - Material Safety Data Sheet


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