Ammonium tetraborate

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Crystal compoundsSaltsBoratesAmmonium tetraborate


  Ammonium tetraborate   
Names: ammonium tetraborate

Formula: (NH4)2B4O7 (anhydrous)
(NH4)2B4O7 · 4H2O (tetrahydrate)
SMILES: B(O)(O)O.B(O)(O)O.B(O)(O)O.B(O)([O-])[O-].[NH4+].[NH4+]
Molar mass: 191.315 g/mol (anhydrous)
263.374 g/mol (tetrahydrate)
Density: 1.58 g/cm3 (anhydrous)
2.37 g/cm3 (tetrahydrate)
Crystal system: tetragonal (tetrahydrate)
α=90°
90°  
, β=90°
90°  
, γ=90°
90°  

Shapes:
https://media.crystalls.info/w/uploads/media/Tetragonal_pyramid.json

Color: colorless
Decomposition point: 87 °C
360.15 K
188.6 °F
648.27 °R
(tetrahydrate)
Magnetic properties: diamagnetic
Stability: stable (tetrahydrate)
Hardness: relatively strong
Toxicity: non-toxic
LD50=4200mg/kg

Description

Inorganic compound, salt of ammonium ion and inorganic tetraboric acid. From water solutions crystallizes as tetrahydrate.

Precursors

Reaction between ammonia and boric acid

Chemical equation:

4H3BO3 + 2NH4OH = (NH4)2B4O7 + 7H2O

For preparation of 100.00g of ammonium tetraborate tetrahydrate а 106.45g of 25% ammonia and 93.91g of boric acid is required.
Add hot acid to the flask, then add small parts of ammonium compound with stirring until heating will stop (attention, the solution may boil!) . After reaction will stop, filter the solution and use it for crystal growing.

Influence of temperature

Very slow crystallization and low transparency at room temperature, but growing from hot solution eliminates these drawbacks.

Storage conditions

Store in its original form or under several layers of varnish at average humidity and room temperature. Do not store in matchboxes or cotton wool and do not heat.

Solubility

Temperatureгр/100,00 гр water
(anhydrous)(tetrahydrate)
0°C
273.15 K
32 °F
491.67 °R
3.75
3.75 g/100g
3.614 %
~5.2
5.2 g/100g
4.943 %
10°C
283.15 K
50 °F
509.67 °R
~3.9
3.9 g/100g
3.754 %
5.3
5.3 g/100g
5.033 %
15°C
288.15 K
59 °F
518.67 °R
~4.60
4.6 g/100g
4.398 %
~6.29
6.29 g/100g
5.918 %
20°C
293.15 K
68 °F
527.67 °R
~5.3
5.3 g/100g
5.033 %
7.27
7.27 g/100g
6.777 %
25°C
298.15 K
77 °F
536.67 °R
9
9 g/100g
8.257 %
~12.5
12.5 g/100g
11.111 %
30°C
303.15 K
86 °F
545.67 °R
~11.4
11.4 g/100g
10.233 %
~15.8
15.8 g/100g
13.644 %
40°C
313.15 K
104 °F
563.67 °R
~16.3
16.3 g/100g
14.015 %
~22.5
22.5 g/100g
18.367 %
50°C
323.15 K
122 °F
581.67 °R
21.2
21.2 g/100g
17.492 %
~29.2
29.2 g/100g
22.601 %
60°C
333.15 K
140 °F
599.67 °R
~29.1
29.1 g/100g
22.541 %
~42.1
42.1 g/100g
29.627 %
70°C
343.15 K
158 °F
617.67 °R
~37.0
37 g/100g
27.007 %
~55.0
55 g/100g
35.484 %
80°C
353.15 K
176 °F
635.67 °R
~44.9
44.9 g/100g
30.987 %
~67.9
67.9 g/100g
40.441 %
90°C
363.15 K
194 °F
653.67 °R
52.7
52.7 g/100g
34.512 %
80.7
80.7 g/100g
44.66 %

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