Preparation and calibration:

一、配制：将氢氧化钠配成饱和溶液，注进塑料桶中密闭放置溶液清亮，使用前以塑料管虹吸上层清液。浓度氢氧化钠饱和溶液注进不含CO2的水0.1mol/L量取5ml1000中摇匀0.2mol/L量取10ml1000中摇匀0.5mol/L量取26ml1000中摇匀1.0mol/L量取52ml1000中摇匀

1、 Preparation: prepare sodium hydroxide into a saturated solution, inject it into a plastic bucket and place it tightly until the solution is clear. Siphon the supernatant with a plastic pipe before use. Inject 0.1mol/l of CO2 free water into the saturated solution of sodium hydroxide, take 5ml of 1000, shake well, take 0.2mol/l of 10ml of 1000, take 26ml of 1000, shake well, take 1.0mol/l of 52ml of 1000, shake well

二、标定：

2、 Calibration:

1、原理：KHC8H4O4＋NOH→KNaC8H4O4＋H2O酸式酚酞碱式酚酞HIn→In-+H+（无色）（红色）酚酞为一有机弱酸，在酸性溶液中为无色，当碱色离子增加到一定浓度时，溶液即呈粉红色。

1. Principle: khc8h4o4 + Noh → knac8h4o4 + H2O acid phenolphthalein basic phenolphthalein Hin → in - + H + (colorless) (red) phenolphthalein is an organic weak acid and colorless in acidic solution. When the alkali ion increases to a certain concentration, the solution will turn pink.

2、仪器：滴定管50ml；三角瓶250ml。

2. Instrument: burette 50ml; Triangular flask 250ml.

3、标定过程0.1mol/LNOH标准溶液称取0.4－0.6克；0.2mol/L称1－1.2克；0.5mol/L称取3克于105－110℃烘恒重的苯二甲酸氢钾，称准0.0002克，分别溶于50ml；80ml不含二氧化碳水中,加2滴1％酚酞指示剂，用配好的待标定溶液溶液呈粉红色与标准色相同。同时作空缺试验。

3. Weigh 0.4-0.6g of 0.1mol/lnoh standard solution during calibration; 0.2mol/l weighs 1-1.2g; 0.5mol/l weigh 3 g of potassium hydrogen phthalate baked to constant weight at 105-110 ℃, weigh to 0.0002 g, and dissolve in 50ml respectively; 80ml carbon dioxide free water, add 2 drops of 1% phenolphthalein indicator, and use the prepared solution to be calibrated until the solution is pink and the same as the standard color. At the same time, the vacancy test is carried out.

4、计算：C（NaOH）=m/(V1-V2)*0.2042C（NaOH）---氢氧化钠溶液浓度m——苯二甲酸氢钾之质量（克）V1——氢氧化钠溶液用量（毫升）V2——空缺氢氧化钠溶液用量（毫升）0.2042——与1.000mol/LNOH标准溶相当的以克表示确当量苯二甲酸氢钾之质量

4. Calculation: C (NaOH) = m / (V1-V2) * 0.2042c (NaOH) -- concentration of sodium hydroxide solution m -- mass of potassium hydrogen phthalate (g) V1 -- dosage of sodium hydroxide solution (ML) V2 -- dosage of vacant sodium hydroxide solution (ML) 0.2042 -- mass of potassium hydrogen phthalate equivalent to 1.000mol/lnoh standard solution expressed in grams

5、留意事项：

5. Precautions:

1、为使标定的浓度正确，标定后应用相应浓度盐酸对标。

1. In order to make the calibrated concentration correct, the corresponding concentration of hydrochloric acid shall be used for benchmarking after calibration.

2、液溶有效期2个月。

2. The validity period of liquid solution is 2 months.

3、氢氧化钠饱和溶液之配制：于1000硬质容器中，加70毫升水，逐渐加进700克氢氧化钠。随加随搅拌，使溶解完全冷却后移进盛氢氧化钠饱和液之试瓶中，以胶塞密塞，静置7天以上，使含之碳酸钠沉淀完全。取澄清之氢氧化钠饱和液少许，加水稀释，加氢氧化钡饱和液1毫升，十分钟内不产生浑浊，表示碳酸钠已沉淀完全。浓度：氢氧化钠溶解度111g/100ml(20°C)

3. Preparation of saturated sodium hydroxide solution: add 70 ml of water to 1000 hard containers and gradually add 700 g of sodium hydroxide. Stir as you add it to make it dissolve completely, cool it, transfer it to the test bottle containing sodium hydroxide saturated solution, plug it with glue, and let it stand for more than 7 days to make the sodium carbonate precipitate completely. Take a little clarified sodium hydroxide saturated solution, dilute it with water, add 1ml barium hydroxide saturated solution, and there is no turbidity within ten minutes, indicating that sodium carbonate has been completely precipitated. Concentration: sodium hydroxide solubility 111g / 100ml (20 ° C)

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