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Calculation method

The following relations exist among mass of solute, volume of solution, etc.

    W = 100M_a/M,   M = M_a+M_b = VD,   C = 1000M_a/FV,   R = V/M_b,   1L = 1000mL

where M_a(g) is mass of NaOH, M_b(g or mL) mass or volume of water before dissolution, M(g), V(mL), D(g/mL), W(%), and C(mol/L) mass, volume, density, mass percentage, and molarity of solution after dissolution, R volume of solution after dissolution/volume of H₂O before dissolution, F(g/mol) formula weight of NaOH.

An unknown value can be calculated with the use of relations shown above and known values.

You may use the upper table to convert concentration to density, volume of solution/volume of H₂O to concentration.

Preparation method

Wash and dry apparatus beforehand.
1  Measure distilled water with a measuring cylinder.
2  Weigh NaOH with a balance, dissolve NaOH with the disstilled water into a beaker.
3  If you need, transfer the solution to a reagent bottle and attach label showing the reagent's name, concentration, date, the person who prepared.

Caution

There is deliquescence in the solid (pellet) of sodium hydroxide.  When the humidity in the air is absorbed it becomes sticky.  When using a balance, put a piece of paraffin paper between the beaker and the platform of balance to shield the platform from corroding with the spilt pellet.  When measuring mass, carry out quickly.  Immediately, keep the remaining solid sodium hydroxide in a bottle and firmly shut the lid of the bottle.

Carefully operate the balance.  Don't load over the maximum limit.  Clean when you spill chemicals.

Keep particularly in mind that it generates strong heat and steam comes out when dissolving sodium hydroxide with water.  There is toxicity in the steam (sodium hydroxide aqueous solution) thus, there is a pungent smell.  Deal with it in a well ventilated place so that steam may not be inhaled.  In adjusting the total volume of solution, do it after getting cold.

If sodium hydroxide solution gets in contact with the eyes or spilled into the skin immediately wash it with water.

Since the pellet of solid sodium hydroxide is large, you can not measure the just prescribed mass.  If exact concentration of dilute sodium hydroxide solution is required, titrate it against a solution of an acid of known concentration, a standard solution; then, you can determine its exact concentration.