Citric acid

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  Citric acid   
Names: 2-oxypropane-1,2,3-tricarboxylic acid
2-hydroxypropane-1,2,3-tricarboxylic acid

Formula: C3H5O(COOH)3 (anhydrous)
C3H5O(COOH)3 · H2O (monohydrate)
SMILES: C(C(=O)O)C(CC(=O)O)(C(=O)O)O
Molar mass: 192.123 g/mol (anhydrous)
210.137 g/mol (monohydrate)
Density: 1.665 g/cm3 (anhydrous)
1.542 g/cm3 (monohydrate)
Crystal system: monoclinic (anhydrous)
a=12.817 Å
12.8170 Å
1.2817 nm
, b=5.628 Å
5.6280 Å
0.5628 nm
, c=11.465 Å
11.4650 Å
1.1465 nm
α=90°
90°  
, β=111.22°
111°13′12.0″  
, γ=90°
90°  

orthorhombic (monohydrate)
α=90°
90°  
, β=90°
90°  
, γ=90°
90°  

Shapes:
https://media.crystalls.info/w/uploads/media/Truncated_rhombic_bipyramid.json
https://media.crystalls.info/w/uploads/media/Truncated_rhombic_pyramid.json

Template:Rhombohedron

Color: colorless
Melting point: 153.5 °C
426.65 K
308.3 °F
767.97 °R
(anhydrous)
Decomposition point: 175 °C
448.15 K
347 °F
806.67 °R
(anhydrous)
Refractive index: 1.46 (anhydrous)
1.498 (monohydrate)
Stability: slightly erodes (monohydrate)
hygroscopic (anhydrous)
Hardness: fragile
Toxicity: non-toxic
LD50=3000mg/kg

Description

Organic compound, tribasic carboxylic acid. From water solutions crystallizes as monohydrate.

Where to buy

In grocery store (as "citric acid").

Precursors

Reaction between sodium citrate, calcium chloride or nitrate and sulfuric acid

Chemical equation:

2Na3C3H5O(COO)3 + CaCl2 = Ca3(C3H5O(COO)3)2↓ + 2NaCl
2Na3C3H5O(COO)3 + Ca(NO3)2 = Ca3(C3H5O(COO)3)2↓ + 2NaNO3
Ca3(C3H5O(COO)3)2 + 3H2SO4 = 2C3H5O(COOH)3 + 3CaSO4

For preparation of 100.00g of citric acid monohydrate а 104.25g of calcium chloride hexahydrate or 112.38g of calcium nitrate tetrahydrate or 189.21g of 37% sulfuric acid is required.
Add to the flask with sodium citrate solution small parts of calcium compounds solution and stir. The large amount of poorly soluble precipitate will form. Settle it out and wash it from soluble impurities few times.Add to the flask with calcium citrate solution small parts of sulfuric acid solution and stir. The large amount of poorly soluble precipitate will form. Settle it out and discard, then filter the solution carefully.

Influence of temperature

If you used hot water to dissolving compound, it formes a syrup which crystllizes even after freezing.

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 waterгр/100,00 гр ethanolгр/100,00 гр methanolгр/100,00 гр diethyl etherгр/100,00 гр DMSOгр/100,00 гр ethyl acetateгр/100,00 гр formic acid 95%гр/100,00 гр propanolгр/100,00 гр dioxaneгр/100,00 гр amyl alcoholгр/100,00 гр trichlorethylene
(anhydrous)(monohydrate)(anhydrous)(monohydrate)(monohydrate)(anhydrous)(monohydrate)(anhydrous)(monohydrate)(anhydrous)(monohydrate)(anhydrous)(monohydrate)(anhydrous)
0°C
273.15 K
32 °F
491.67 °R
32.66
32.66 g/100g
24.619 %
10°C
283.15 K
50 °F
509.67 °R
35.02
35.02 g/100g
25.937 %
117.4
117.4 g/100g
54.002 %
15°C
288.15 K
59 °F
518.67 °R
~47.1
47.1 g/100g
32.019 %
~131
131 g/100g
56.71 %
0.012
0.012 g/100g
0.012 %
20°C
293.15 K
68 °F
527.67 °R
59.2
59.2 g/100g
37.186 %
145.1
145.1 g/100g
59.2 %
200
200 g/100g
66.667 %
40
40 g/100g
28.571 %
12.25
12.25 g/100g
10.913 %
62.6
62.6 g/100g
38.499 %
25°C
298.15 K
77 °F
536.67 °R
~163
163 g/100g
61.977 %
62
62 g/100g
38.272 %
99.2
99.2 g/100g
49.799 %
1.05
1.05 g/100g
1.039 %
2.25
2.25 g/100g
2.2 %
5.6
5.6 g/100g
5.303 %
35.9
35.9 g/100g
26.416 %
18.25
18.25 g/100g
15.433 %
30°C
303.15 K
86 °F
545.67 °R
180.1
180.1 g/100g
64.298 %
40°C
313.15 K
104 °F
563.67 °R
218.5
218.5 g/100g
68.603 %
50°C
323.15 K
122 °F
581.67 °R
243.6
243.6 g/100g
70.896 %
60°C
333.15 K
140 °F
599.67 °R
277.4
277.4 g/100g
73.503 %
70°C
343.15 K
158 °F
617.67 °R
320.2
320.2 g/100g
76.202 %
80°C
353.15 K
176 °F
635.67 °R
371.7
371.7 g/100g
78.8 %
90°C
363.15 K
194 °F
653.67 °R
437.6
437.6 g/100g
81.399 %
100°C
373.15 K
212 °F
671.67 °R
525.0
525 g/100g
84 %
Insoluble in toluene, benzene and carbon disulfide.

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