What Is Boric Acid?
Boric acid, chemical formula HBO, is white powder crystal or scaly glossy crystal with three oblique axes, which has a smooth feel and no odor. Soluble in water, alcohol, glycerin, ethers and essential oils. The aqueous solution is weakly acidic. It is widely used in the glass (optical glass, acid-resistant glass, heat-resistant glass, and glass fiber for insulating materials) industry. It can improve the heat resistance and transparency of glass products, improve mechanical strength, and shorten melting time.
- White powder crystal or scaly glossy crystal with three oblique axes. Has a slippery feel and no odor. Soluble in water, alcohol, glycerin, ethers and essential oils. No smell. Slightly sour and bitter with sweetness. It feels slippery when in contact with the skin. No change in exposed air. Can follow
- If the laboratory is splashed with strong alkali (NaOH or KOH), in addition to rinsing with a large amount of water (HO), it should also be coated with a boric acid solution. To neutralize residual strong bases. This is one of the most basic and closest uses to life. (If the boric acid-free solution is splashed with strong alkali, carbonic acid can be used in emergency, but boric acid is preferred because boric acid is also an acid, which is weaker than the carbonic acid in cola.)
- Preparation
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- Method name:
- Boric acid-determination of boric acid-neutralization titration
- Application:
- This method uses neutralization titration to determine the content of boric acid (H3BO3).
- This method is applicable to the determination of boric acid.
- Method principle:
- Take an appropriate amount of the test product, add mannitol and freshly boiled cold water, dissolve it at a slight temperature, immediately cool to room temperature, add a phenolphthalein indicator solution, and titrate with sodium hydroxide titration solution (0.5mol / L) until it becomes pink. Each 1mL of sodium hydroxide titration solution (0.5mol / L) is equivalent to 30.92mg of H3BO3, which is calculated.
- Note 1: "Precision weighing" means that the weighed weight should be accurate to one thousandth of the weight. Precision requirements.
- Note 2: "Determination of moisture" uses the drying method, taking 2 to 5 g of the test sample, and spreading it in a flat weighing bottle that is dry to constant weight, the thickness does not exceed 5 mm, and the loose test sample does not exceed 10 mm. Open the bottle cap and dry at 100 ~ 105 ° C for 5 hours. Place the cap on the dryer, cool it for 30 minutes, and weigh it precisely. Then dry it at the above temperature for 1 hour, cool, and weigh until two times in a row. The difference in weighing does not exceed 5 mg. Calculate the moisture content (%) in the test product based on the weight lost. [4]
- Its acidic source does not give protons by itself, because boron is an electron-deficient atom, it can add
- Manufacturing method and process 1,
- It should be stored in a dry and clean warehouse, and should not be stored in the open air. It should be protected from rain or moisture. It should be transported in boxcars, cabins or cars with sheds. It should not be mixed with wet items and colored raw materials. The transportation means must be dry and clean.
- Properties: white powder crystal or colorless scaly crystal with three oblique axes.
- Uses: used as glass,
- The boric acid is heated to 100 ° C. Due to the constant loss of moisture, it first becomes metaboric acid. It has three variants with melting points of 176 ° C, 201 ° C and 236 ° C. The dehydration of boric acid to the end of metaboric acid is complete (as long as the temperature does not exceed 150 ° C). Heating is continued, and water is removed to form boron oxide. Crystal boron oxide melts at 450 ° C. Amorphous boron oxide does not have a fixed melting point. It begins to soften at 325 ° C and all become liquid at 500 ° C.
- stability
- Boric acid is a stable crystal that usually does not occur under storage
- Name: Boric acid; boric acid (medical grade)
- boric acid
- Boracic acid
- Molecular formula: H3BO3
- [Chinese name]: Boric acid
- [Simplified Pinyin]: PS
- [English name]: Boric Acid
- [Category]: Dermatological Drugs ||
- Boric acid
- Global distribution of boron resources
- Boron resources are global, with Turkey's better resources and larger reserves. China has abundant boron reserves, second only to Turkey, the United States and Russia. The development and utilization of boron resources in Chile has developed rapidly. North Korea has also identified and started to use boron resources.
- Distribution of boron resources in China
- China's boron resources are mainly distributed in Liaoning, especially Fengcheng Kuandian in Dandong area, which is known as "China's boron capital". The Wengquangou boron-iron deposit in Fengcheng is the only extra-large and Asia's largest boron-iron deposit proven in China. It is also distributed in Qinghai and Tibet. It is distributed in a small amount in North China, South China, Central South and East China.
- The advantages of boron resources provide the foundation and guarantee for the development of boric acid industry. The development and utilization of boric acid has become one of the pillar industries in Dandong. [3]
Boric acid method name
- Boric acid-determination of boric acid-neutralization titration
Application range of boric acid
- This method uses neutralization titration to determine the content of boric acid (H3BO3). This method is applicable to the determination of boric acid. [1]
Boric acid method principle
- Take an appropriate amount of the test product, add mannitol and freshly boiled cold water, dissolve it at a slight temperature, immediately cool to room temperature, add a phenolphthalein indicator solution, and titrate with sodium hydroxide titration solution (0.5mol / L) until it becomes pink. Each 1mL of sodium hydroxide titration solution (0.5mol / L) is equivalent to 30.92mg of H3BO3, which is calculated.
- Reagents: 1. Water (new boiling to room temperature) 2. Mannitol 3. Sodium hydroxide titration solution (0.5mol / L) 4. Phenolphthalein indicator solution 5. Reference potassium hydrogen phthalate [1]
Boric acid equipment
- Sample preparation:
- 1. Sodium oxide titration solution (0.5mol / L)
- Preparation: Take an appropriate amount of sodium hydroxide, add water and shake to dissolve it into a saturated solution. After cooling, place it in a polyethylene plastic bottle and let it stand for several days. Take 28 mL of a clear saturated sodium hydroxide solution, add freshly boiled cold water to 1000 mL, and shake well.
- Calibration: Take about 3g of standard potassium hydrogen phthalate dried to constant weight at 105 ° C, weigh it accurately, add 50mL of freshly boiled cold water, shake it to dissolve it as much as possible, add 2 drops of phenolphthalein indicator liquid, use this For liquid titration, near the end, potassium hydrogen phthalate should be completely dissolved, and the solution should be titrated until the solution becomes pink. Each 1mL of sodium hydroxide titration solution (0.5mol / L) is equivalent to 102.1mg of potassium hydrogen phthalate. Calculate the concentration of this solution based on the consumption of this solution and the amount of potassium hydrogen phthalate taken.
- Storage: Put it in a polyethylene plastic bottle and keep it in a sealed container. There are 2 holes in the plug. One glass tube is inserted into the hole. One tube is connected to the soda lime tube. One tube is used to suck out the liquid.
- 2.phthalein indicator liquid
- Take 1 g of phenolphthalein and add 100 mL of ethanol to dissolve.
- Operation steps: Take about 0.5g of this product, accurately weigh it, add 5g of mannitol and 25mL of freshly boiled cold water, dissolve it at a slight temperature, let it cool to room temperature, add 3 drops of phenolphthalein indicator solution, and titrate with sodium hydroxide ( 0.5mol / L) Titrate until pink. [4]
Boric acid solubility
- As the temperature increases, its dissolution increases. [1]