Reagents

I cannot give you directions to prepare every possible strength of every known reagent, but I can give you enough examples to figure out how to prepare any percentage or strength you might need to prepare. No matter what you are making, the rules below are to be followed.

1. Only the purest chemicals should be used unless another grade is specifically recommended.

2. Analytical (extremely accurate) balances should be used for weighing chemicals.

3. When measuring liquids, use a class A volumetric pipette unless otherwise specified.

4. Do not pipette strong acids or alkalis by mouth. Use a rubber bulb or an adjustable vacuum source.

5. Hot and cold liquids should be allowed to come to room temperature before measurement.

6. Only distilled or deionized water is to be used.

7. Mix thoroughly after dilution.

8. Light sensitive reagents are to be stored out of the light. Figure 19

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ACETIC ACID 10%

Pipette 1 ml of glacial acetic acid into a 100 ml volumetric flask. Dilute to volume with water and mix.

ACETIC ACID 10%

Measure 100 ml of glacial acetic acid and transfer to a 1 L volumetric flask containing about 600 ml of water. Mix, dilute to volume with water and mix again.

ACETIC ACID 50%

Add 50 ml of glacial acetic acid to 50 ml of water and mix. A CETONE-ALCOHOL MIXTURE

Mix 500 ml reagent grade acetone with 500 ml of 95% ethyl alcohol. ACETONE-ETHER MIXTURE

Mix 200 ml of reagent grade ether with 100 ml of reagent grade acetone. AMMONIUM HYDROXIDE, DILUTE (0.5%)

Transfer 2 ml of concentrated (28%) ammonium hydroxide to a flask and add 98 ml of water. Keep no longer than 1 month.

AMMONIUM HYDROXIDE 5%

Mix 20 ml of ammonium hydroxide (this is concentrated, 28%) with 80 ml of water. Store in a glass stoppered bottle.

AMMONIUM HYDROXIDE 10%

Mix 36 ml of cone, ammonium hydroxide with 74 ml of water. CALCIUM CHLORIDE 2.5%

Weigh 2.5 g of calcium chloride, and transfer to a 100 ml flask. Dissolve and dilute to volume with water and mix.

CALCIUM CHLORIDE 10%

Weigh 10 g of calcium chloride, and transfer to a 100 ml flask. Dissolve and dilute to volume with water and mix.

HYDROCHLORIC ACID 0.05 N

Place 900 ml of water in a 1 L flask and add 4.2 ml of cone, hydrochloric acid. Dilute to volume (1000 ml) and mix well.

HYDROCHLORIC A CID 0.25 N

Place 500 ml of water in a 1 L volumetric flask. Carefully measure 21 ml of cone, hydrochloric acid in a 25 ml graduated cylinder and add to the flask. Rinse the cylinder with water and add the washings to the flask. Mix, dilute to volume and mix again. Add 0.5 ml of Brij 35 and mix thoroughly.

HYDROCHLORIC ACID 1 N

Add 8.4 ml of cone, hydrochloric acid to a volumetric flask containing 70 ml of water. Dilute to volume and mix.

HYDROCHLORIC ACID 2 N

Add 167 ml of hydrochloric acid to a volumetric flask containing 600 ml of water. Dilute to volume and mix.

HYDROCHLORIC ACID 6 N

Slowly and while mixing add 500 ml of cone, hydrochloric acid to 500 ml of water and mix well.

HYDROCHLORIC ACID 5%

Dilute 5 ml of the acid in 95 ml of water and mix.

POTASSIUM HYDROXIDE 1.25 N

Add 70 g of potassium hydroxide to a volumetric flask containing 600 ml of water. Mix to dissolve and cool to room temperature. Dilute to volume with water and mix well.

POTASSIUM HYDROXIDE 33%

Add 330 g of potassium hydroxide to a 1 L volumetric flask containing 300 ml of water. Cool, dilute to volume and mix.

SODIUM CHLORIDE, SA TURA TED

Add 40 g of sodium chloride to 100 ml of hot water and mix.

SODIUM HYDROXIDE 0.0075 N

Add 7.5 ml of 1 N sodium hydroxide to a volumetric flask containing 800 ml of water. Mix, dilute to volume, and mix again.

SODIUM HYDROXIDE 0.01N

Put 1 ml of 1 N sodium hydroxide into a 100 ml volumetric flask and dilute to volume with water and mix.

SODIUM HYDROXIDE 0.05 N

Prepare from a concentrated solution of sodium hydroxide that has been standardized, ml x N = ml x N. Standardize this dilute solution against a standard acid solution and adjust to 0.05 N if necessary.

SODIUM HYDROXIDE. IN

Put 100 ml of 1 N sodium hydroxide into a 1 L volumetric flask and dilute to volume with water and mix.

SODIUM HYDROXIDE 0.4 N

This may be prepared from a concentrated solution of sodium hydroxide that has been standardized. Or: Weigh 16 g of sodium hydroxide pellets and transfer to a 1 L volumetric flask. Dissolve and dilute to volume with water and mix well. SODIUM HYDROXIDE 1 N

Prepare from a concentrated solution of sodium hydroxide that has been standardized. Standardize the diluted solution against 1 N acid. Adjust to 1 N, if necessary.

SODIUM HYDROXIDE 2.5 N (10%)

Dilute solutions should be prepared by using a nearly saturated solution that has been standardized. If the normality of the concentrated solution is known, then the volume needed to make a dilute solution may be determined with the following formula:

ml x N - ml x N Or: 10% (2.5 N) can be done as follows

Weigh 100 g of sodium hydroxide pellets and transfer to a 1 L volumetric flask containing 800 ml of water. Mix to dissolve, cool to room temperature, dilute to volume and mix.

SODIUM HYDROXIDE 40%

Weigh 40 g of sodium hydroxide pellets and transfer to a pyrex 100 ml volumetric flask containing 50 ml of water. Swirl or mix to dissolve. Cool to room temperature, dilute to volume and mix again.

As you should have noticed, percentages are easy to figure out how much reagent to mix with your water. With the formula above and standardized solutions you can also figure the strength in N measurement quite easily.

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