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, b=5.628 Å, c=11.465 Åα=90°, β=111.22°, γ=90°
orthorhombic (monohydrate)
α=90°, β=90°, γ=90°
Shapes:
https://en.crystalls.info/w/uploads/media/Truncated_rhombic_bipyramid.json
https://en.crystalls.info/w/uploads/media/Truncated_rhombic_pyramid.json

Template:Rhombohedron

Color: colorless
Melting point: 153.5 °C426.65 K <br />308.3 °F <br />767.97 °R <br /> (anhydrous)
Decomposition point: 175 °C448.15 K <br />347 °F <br />806.67 °R <br /> (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 use hot water to dissolve compound, it formes a syrup which doesn´t crystallize 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°C273.15 K <br />32 °F <br />491.67 °R <br />32.66
10°C283.15 K <br />50 °F <br />509.67 °R <br />35.02117.4
15°C288.15 K <br />59 °F <br />518.67 °R <br />~47.1~1310.012
20°C293.15 K <br />68 °F <br />527.67 °R <br />59.2145.12004012.2562.6
25°C298.15 K <br />77 °F <br />536.67 °R <br />~1636299.21.052.255.635.918.25
30°C303.15 K <br />86 °F <br />545.67 °R <br />180.1
40°C313.15 K <br />104 °F <br />563.67 °R <br />218.5
50°C323.15 K <br />122 °F <br />581.67 °R <br />243.6
60°C333.15 K <br />140 °F <br />599.67 °R <br />277.4
70°C343.15 K <br />158 °F <br />617.67 °R <br />320.2
80°C353.15 K <br />176 °F <br />635.67 °R <br />371.7
90°C363.15 K <br />194 °F <br />653.67 °R <br />437.6
100°C373.15 K <br />212 °F <br />671.67 °R <br />525.0
Insoluble in toluene, benzene and carbon disulfide.


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