BROMCRESOL GREEN-METHYL RED INDICATOR POWDER PILLOWS May cause eye, skin and
respiratory tract irritation. Do not ingest, inhale, or allow contact with skin or eyes. In case of
contact, immediately flush eyes and skin with water for 15 minutes. In case of ingestion,
immediately give large quantities of water. In case of inhalation, remove victim to fresh air. Call
medic in all cases.
Add the contents of one bromcresol green-methyl red indicator powder pillow(2) to the water sample in the
mixing bottle(5). Swirl to mix.
If the water turns either gray-blue, blue, or green the free acidity is zero. Then the test is complete. If the
water turns pink go to step (4).
SODIUM HYDROXIDE STANDARD SOLUTION Causes burns. Harmful if swallowed. Do not
ingest or allow contact with skin or eyes. In case of contact, immediately flush eyes and skin
with water for 15 minutes. Remove contaminated clothing. In case of ingestion, DO NOT induce
vomiting. Give large quantities of water. Give at least one ounce of vinegar in an equal amount
of water. Call medic in all cases.
If the water turns pink during step (3), add standard sodium hydroxide solution(l) drop by drop until the
water just begins to turn gray-blue. Count the drops as they are added. Record the number of drops.
Constantly swirl the mixing bottle(5) while adding the sodium hydroxide(l).
If after adding 30 drops of sodium hydroxide solution, the solution does not change back to
gray-blue, stop the test and carry out the Free Acidity Test, High Range (para 220.127.116.11).
Interpretation of Results:
If the water is gray-blue, blue or green at the end of step (3), the free acidity is zero.
If not zero, the free acidity (in mg/l of calcium carbonate equivalents) is equal to 5 times the number of
drops of sodium hydroxide standard solution used.
18.104.22.168. Total Acidity Test. High Range.
Purpose of Test: To determine the total acidity in a water sample in terms of the amount of calcium carbonate
required to neutralize the sample.
Range: From 0 to 500 mg/l of calcium carbonate equivalents
Equipment Used: Found in Acidity Test Kit, para 2.6.3, fig. 2-7
Standard sodium hydroxide solution, (1), fig. 2-7
Test tube, (3), fig. 2-7
Phenolphthalein indicator solution, (4), fig. 2-7
Mixing bottle, (5), fig. 2-7
General Techniques Used: Refer to paragraphs cited below as required by procedure.
Planning the Test, para 22.214.171.124
Cleaning Glassware, para 126.96.36.199
Handling and Storing Reagents, para 188.8.131.52
Collecting Water Samples, para 184.108.40.206
Mixing, para 220.127.116.11
Titrating, para 18.104.22.168