Some data and solubility information for
Sodium Chlorate

Technical Data And Physical Properties

Chemical Properties. Sodium Chlorate is a powerful oxidizing agent. When heated in the pure state, it will begin to decompose slowly at about 300° (570°). with the evolution of oxygen and the formation of Sodium Chloride. This decomposition is strongly exothermic and self-sustaining above a critical temperature. The large amounts of Oxygen released can cause the burning of combustible materials to be explosively rapid.

As shipped, Sodium Chlorate is not a fire or explosion hazard. However, many substances when combined with Sodium chlorate form explosive mixtures. Such combinations, particularly those containing certain organic materials, can be extremely sensitive to shock, friction or heat. Organic contaminants in this category include alcohols, solvents, sugars, sawdust, paint, lint, vegetable dusts, oils and greases.

The primary inorganic contaminants to avoid are sulfur, sulfides, ammonium compounds, phosphorus, cyanides, powdered metals, acids, or any kind of reducing agent.

When impregnated with chlorate from contact with an aqueous solution, combustible materials such as paper, wood, cloth and leather become dangerously flammable if dry and may be ignited by friction, heat or a drop of strong acid.

Alkaline chlorate solutions do not exhibit strong oxidizing properties. However, as pH decreases, the oxidizing activity of these solutions will increase. Concentrated acid solutions are vigorous oxidizing agents.

Commercial sodium chlorate solutions are neutral or slightly basic. Under these conditions they are stable in storage over a long period of time.

Figure 9

Sodium Chloride Concentration (wt% NaCl)

This chart presents composition and saturation temperature data for mixtures of salt and sodium chlorate dissolved in water. The composition and saturation temperature can be obtained for any point on the sodium chlorate saturation surface. Sodium chlorate solubility isotherms are drawn for every 20° interval from -20° to 100°. As an example, the saturation temperature of a water solution containing 40% NaClO₃ and 4% NaCl was estimated: The location of this composition was found to lie between the NaClO₃ saturation isotherms for 0°C and 20°C. By interpolation, the saturation temperature was estimated at 5°C.

This table shows some data points of saturation from the graph above(Fig 9). The amounts of dissolved solids are shown as both weight% and grams solute per 100g water
ZERO DEGREES CO NaCl NaClO3 Weight% g/100g water Weight% g/100g water 0 0 44.5 80 7 7.5 35 54 11 12.8 30 43 16.1 19.2 24 31.6 20 25 15 17.6 23 30 8 8.7 26 35 0 0	FORTY DEGREES CO NaCl NaClO3 Weight% g/100g water Weight% g/100g water 0 0 54 117.4 9.2 10.1 41 69.5 20 25 16 19 26.5 36 0 0
EIGHTY DEGREES CO NaCl NaClO3 Weight% g/100g water Weight% g/100g water 0 0 63.5 174 5.2 5.5 57.2 133 12 13.6 37 59 27.2 37.4 0 0	ONE HUNDRED DEGREES CO NaCl NaClO3 Weight% g/100g water Weight% g/100g water 0 0 68 212 4.5 4.7 63 170 14 16.4 33.1 49.5 28 38.7 0 0

See here for mutual solubility graphs in units of grams and moles solute per 100ml solution.

The graph above was obtained from the table below. And can be useful as a ready reckoner for converting the rather confusing descriptions of chlorate solutions.

The table above shows the density of Sodium chlorate solution at 25C at various concentrations. Note that the weight % is directly convertable to grams chlorate per 100 grams water.
For example if the weight% is 40, that's 40 grams chlorate per 100 grams solution. Thats the same as 40 grams of chlorate in 60 grams water, which is the same as (40 X 100/60) = 66.666g/100g water.

Density of Sodium Chlorate Solutions

The following equation can be used to calculate the density of Sodium Chlorate solutions at varying temperatures and concentrations.

The graph above shows the density of a solution of sodium chlorate in solution at different concentrations and at a few different temperatures. Each line is giving similar data to the table above which shows density of sodium chlorate at 25C. There is no data for 25C which is the temperature used in the table above, if you were to put in a line between 20 and 40C you would get the same figures as the table above. The graph dosen,t show grams/liter like the table.

The graph above shows the density of 'R-2' solution, which is 25.5wt% chlorate, 15wt% chloride. 'R-2' is the industrial name of this concentration of solution.

The graph above shows the density of sodium chlorate + sodium chloride at various chosen sodium chloride percentages. All percentages are weight. The temperature is 25C.

The graph above shows the density of sodium chlorate + sodium chloride at various chosen sodium chloride percentages. All percentages are weight. The temperature is 40C.

The graph above shows the density of sodium chlorate + sodium chloride at various chosen sodium chloride percentages. All percentages are weight. The temperature is 60C.

The graph above shows the density of sodium chlorate + sodium chloride at various chosen sodium chloride percentages. All percentages are weight. The temperature is 80C.

Analytical Properties

Procedure for Determination of NaCl in NaClO₃ Solution by Argentometric Titration

Method

Equipment:

1. Pipet, 50 ml and 20 ml (Class A)
   
2. Volumetric flask 500 ml (Class A)
   
3. Casseroles 210 ml, Erlenmeyer flask, beaker
   
4. Buret 25 ml or automatic Titrator
   
5. Stirring bar and plate (optional)

Reagents:

1. AgNO₃ 0.1 N Titration Solution
   
2. K₂CrO₄ Indicator Solution

Procedure:


A. Sample Solution Preparation


1. Pipet 20 ml of NaClO₃ solution at operating temperature.
   
2. Transfer into 500 ml volumetric flask.
   
3. Fill to mark with DI water and mix.

B. Sodium Chloride Determination

1. Pipet 50 ml of sample solution for solution concentrations
   of 5 to 75 gpl,

   or

   Pipet 5 ml of sample for solution concentrations
   of 75 to 150 gpl.
   

2. Transfer into a titration flask.
   
3. Add approximately 30 ml of DI water.
   
4. Add 5 to 8 drops of KCrO₄ indicator solution.
   
5. Titrate with AgNO₃ 0.1 N until the first appearance of a permanent light pink color.
   
6. Record V₁ = volume of AgNO₃ at end point.

C. Calculation

2.922 x volume of titrant = g/l NaCl (50 ml sample)
29.22 x volume of titrant = g/l NaCl (5 ml sample)
The factor (2.922) is related to the AgNO₃ normality and sample size. See Principle, section B, for further explanation.

Hazards:

Careful handling of chlorate is essential. Contact with any combustibles such as paper, wood, of clothing should be avoided. It is recommended that a metal disposal can for combustibles that have come in contact with chlorate and a container for recycling waste chlorate to the process be made available in the laboratory.

Information concerning the hazards of the chemical products used in this procedure is found in the MSDS file.

Scope:

1. This procedure determines the concentration of Sodium Chloride in Sodium Chlorate solutions with concentration ranges of 5 to 150 gpl.

Principle:

1. Reaction equations In a neutral or slightly alkaline solution, Potassium Chromate indicates the end point of the Silver Nitrate titration of chloride. Silver Chloride is precipitated quantitatively before the red Silver Chromate compound is formed.

   Ag⁺ + Cl^- ------> AgCl (White precipitate)

   2Ag ⁺ + CrO₄^-2 ------> Ag₂CrO₄ (Red color)
   

2. Calculation

   grams/liter NaCl=	(Volume AgNO3) (Normality AgNO3) x 58.44
   	Volume of sample

   Factors may be computed using constants in the formula above.

Precautions:

Because end point recognition is based on color perception, precise end point recognition is difficult. Techs in each laboratory must be trained to detect the correct end point.

Interferences:

pH can effect end point recognition: Cl^- as a contaminant in high purity water can give high results.

Sampling:

Samples will usually be warm when taken. Samples are analyzed at 20° for accurate results, unless otherwise specified by the customer. Samples containing high concentrations of Sodium Chlorate (400-600 gpl) are pipetted as soon as possible as the sample will crystallize.

Hazards:

Silver Nitrate is listed as a poison and corrosive material.
Potassium Chromate is listed as a carcinogen.
Information concerning the hazards of these chemical products can be found in the supplier's MSDS.

Procedure for Determination of NaClO₃ in Solutions of Sodium Chlorate

Method

Equipment:

1. Pipets 5 ml and 20 ml (Class A)
   
2. Volumetric flask 500 ml (Class A)
   
3. Erlenmeyer flasks 250 or 500 ml
   
4. Buret 50 ml (Class A)
   
5. Auto pipet 50 ml
   
6. Dispensette 20 ml
   
7. Hotplate

Reagents:

1. K₂Cr₂O₇ titration solution 0.2818 N
   
2. Indicator, Sodium Diphenylamine Sulphonate
   
3. Fe⁺² solution (Ferrous Sulfate or Ferrous Ammonium Sulfate)
   
4. Mixed acid solution

Procedure:

A. Sample Solution Preparation

1. Pipet 20 ml of Sodium Chlorate solution sample at operating temperature.
   
2. Transfer into 500 ml volumetric flask.
   
3. Fill to mark and mix thoroughly.

B. Sodium Chlorate Determination

1. Pipet 5 ml of the sample solution (from A-3) into Frlenmeyer flask.
   
2. Volumetrically transfer 50 ml of Fe⁺² solution into flask (B-1).
   
3. Add 20 ml mixed acid to the flask and heat to a boil.
   
4. Add approximately 150 ml of DI water to the solution.
   
5. Add 10 drops of indicator.
   
6. Titrate with K₂Cr₂O₇ solution.
   
7. Observe end point (changes from green to purple).
   
8. Record V_x: Volume of the K₂Cr₂O₇ at end point.
   
9. A blank is run using the same procedures except adding 5 ml DI water at step (1) instead of the diluted sample.
   
10. Record V_y: Volume of K₂Cr₂O₇ blank.

C. Calculation:

gpl NaClO3=	(Vy - Vx) (K2Cr2O7N) eq wt. of NaClO3
	actual ml of sample used

• 
  When Utilizing this procedure:

  gpl NaClO3=	(Vy - Vx) (0.2818) (17.74)	or gpl NaClO3 = (Vy - Vx) 25
  	0.20

  V_y = Buret volume of Blank (approx. 40 ml)
  V_x= Buret volume of sample.

Hazards:

Careful handling of chlorate solution is essential. Contact with any combustibles such as paper, wood, or clothing should be avoided.

It is advisable to have a metal disposal can in the laboratory for combustibles that have come in contact with chlorate and a container for recycling waste chlorate to the system.

Dichromates are listed as carcinogens; see the MSDS for Potassium Dichromate in the MSDS manual.

Acids and mixed acid solutions are listed as Corrosives; see the MSDS for the specific acid in the MSDS manual.

Scope:

This procedure determines the concentration of Sodium Chlorate solutions with a range of 200 to 650 gpl.

Principle:
Chlorate is reduced by Fe⁺² in known excess. The remaining unoxidized Fe⁺² is then oxidized to Fe⁺³ by the redox titration of Cr⁺⁶ to Cr⁺³.

A. Reaction Equations: 6Fe⁺² + 6H⁺ + (Cl⁺⁵O₃)^- ------> 6Fe⁺³ + Cl^- + 3H₂O
6Fe⁺² + 14H⁺ + (Cr₂⁺⁶O₇)^-2 ------> 6Fe⁺³ + 2Cr⁺³ + 7H₂O


B. Calculations:

gpl NaClO3=	(Vy - Vx) (K2Cr2O7N) (eq wt. of NaClO3)
	actual ml of sample used

• 
  

  NOTE:

  Vy = buret Volume of blank Vx = buret Volume of sample

  C. Precautions:

  1. To avoid error from slow air oxidation of Ferrous Sulfate (Ferrous Ammonium Sulfate) solution, a blank determination is run as duplicate each day. Also, since the surface is oxidized more rapidly than the solution as a whole, the solution is mixed well each day.
  2. Accurate pipet and buret use is the key to precision and accuracy. Only Class A (TD) pipets and burets are used.
  3. Start and finish the analysis within a certain period of time (approximately 10 minutes). Do not allow the sample to boil too long (approximately 2 minutes).

Interferences:

None observed.

Sampling:

Samples are warm when taken, and during the piping the temperature is maintained.

Equipment:

1. Four place analytical balance
   
2. 2 liter Volumetric flask
   
3. 2 liter solution container, acid cleaned
   
4. 250 ml Erlenmeyer flasks
   
5. 25 ml pipet (Class A)
   
6. Drying oven
   
7. Desicator
   
8. Buret (Class A)

Reagents:

1. K₂Cr₂O₇ Primary Standard or Analytical Grade
   
2. Distilled or Deionized water
   
3. Mixed Acids Solution: (See Mixed Acids Solution, following page)
   
4. Ferrous Iron Solution: (See Fe⁺² Solution 0.056 N, following page)
   
5. Indicator solution, Sodium Diphenylamine Sulfonate: (See Sodium Diphenylamine Sulfonate Indicator Solution Preparation, following page)

Procedure:

A. Solution Preparation

1. Weight 27.6337 g K₂Cr₂O₇ (dried overnight at 104°) Primary Standard or Analytical Reagent Grade.
   
2. Place into a 2 liter Volumetric flask and add high purity water to approximately 1.5 liters. Dissolve and dilute to mark. Pour into a clean, dry container.

B. Standardization Check

1. Make up four 250 ml flasks containing Sodium Chlorate standard solution (See Chlorate Test Check, below) diluted as in procedure step A-2.
   
2. Add 50 ml Ferrous Iron Fe⁺² solution to each using the same pipet each time.
   
3. Add 20 ml mixed acids to each.
   
4. Add DI water to each to an approximate volume of 150 ml and add 10 drops indicator.
   
5. Titrate two flasks with (ref ASTM) primary standard solution and record volume.
   
6. Titrate remaining flasks with working Dichromate solution.
   
7. Results should be within 0.01-0.02 ml.

C. Chlorate Test Check

A Sodium Chlorate Check sample is made from a known amount of Sodium Chlorate (dried at 120°) dissolved to a 600 to 630 gpl NaClO₃ solution. This sample is to be tested on a regular basis and recorded. It is also analyzed when questions arise concerning reagents or procedures.




Ferrous Iron solution Fe⁺² 0.056 N

Procedure:

63.5 g FeSO₄ * 7H₂O + 100 ml of concentrated H₂SO₄ and dilute to l liter with DI water in water bath. (Must be kept cool throughout.)




Mixed Acids Solution

Procedure:

7000 ml DI water, 1500 ml concentrated Sulfuric Acid, & 1500 ml concentrated Phosphoric Acid. Add acid slowly in a water bath.




Sodium Diphenylamine Sulphonate
Indicator Solution

Procedure:

Weigh 1.0 g of reagent and place in a 500 ml Volumetric flask. Add water to dissolve. Then add 25 ml mixed acid solution and dilute to mark with DI water.

Important Legal Notice: The information presented in this manual was prepared by Eka Chemicals Technical Personnel. While not guaranteed, it is true and accurate to the best of our knowledge. Eka Chemicals makes no warranty or guarantee, express or implied, regarding accuracy, completeness, performance, safety or otherwise. This information is not intended to be all-inclusive, as the manner and conditions of use, handling, storage and other factors may involve other or additional safety or performance considerations. While our technical personnel will be available to respond to your questions regarding safe handling and use procedures for sodium chlorate, safe handling and use of the product remain the responsibility of the customer. No suggestions for use are intended as, and nothing herein shall be construed as, a recommendation to infringe any existing patents or to violate any federal, state or local laws. Eka Chemicals assumes no liability of any kind whatsoever resulting from the use of or reliance upon any information, procedure, conclusion or opinion in this manual.

EKA CHEMICALS 1998