Sodium dichromate is a chemical compound. It is an oxidizing agent and a strong toxic substance. It is used in various industrial processes, such as metal plating and the production of pigments.
| IUPAC Name | Sodium dichromate |
| Molecular Formula | Na2Cr2O7 |
| CAS Number | 10588-01-9 |
| Synonyms | Sodium bichromate, Disodium dichromate, Bichromate of soda |
| InChI | InChI=1S/2Cr.2Na.7O/q2*+6;2*+1;7*-2 |
Sodium Dichromate Properties
Sodium Dichromate Formula
The formula of sodium bichromate is Na2Cr2O7. It consists of two sodium atoms (Na), two chromium atoms (Cr), and seven oxygen atoms (O). The formula represents the ratio of each element in the compound.
Sodium Dichromate Molar Mass
The molar mass of sodium bichromate is calculated by adding the atomic masses of all its constituent elements. Sodium (Na) has an atomic mass of 22.99 g/mol, chromium (Cr) has a mass of 51.99 g/mol, and oxygen (O) has a mass of 16.00 g/mol. Adding these values gives a molar mass of 261.97 g/mol for sodium bichromate.
Sodium Dichromate Boiling Point
Sodium bichromate has a boiling point of approximately 400°C (752°F). This is the temperature at which the compound changes from a liquid to a gas phase when heated under normal atmospheric pressure.
Sodium Dichromate Melting Point
The melting point of sodium bichromate is around 357°C (675°F). This is the temperature at which the solid compound transforms into a liquid state. It is important to note that the melting point may vary slightly depending on the purity of the sample.
Sodium Dichromate Density g/mL
The density of sodium bichromate is about 2.52 g/mL. Density is a measure of the mass of a substance per unit volume. In the case of sodium bichromate, this value indicates that a given volume of the compound is relatively heavy.
Sodium Dichromate Molecular Weight
The molecular weight of sodium bichromate is 261.97 g/mol. This value represents the sum of the atomic weights of all the atoms present in one molecule of the compound.
Sodium Dichromate Structure
Sodium bichromate has a crystalline structure, forming bright red-orange crystals. It consists of sodium ions (Na+) and dichromate ions (Cr2O7^2-). The dichromate ion has a central chromium atom bonded to two oxygen atoms on one side and three oxygen atoms on the other side.
Sodium Dichromate Solubility
Sodium bichromate is highly soluble in water. It readily dissolves in water, forming a yellow-orange solution. The solubility of sodium bichromate in water is influenced by factors such as temperature and pH, with higher temperatures and lower pH levels increasing its solubility.
| Appearance | Red-orange crystals |
| Specific Gravity | 2.52 |
| Color | Bright red-orange |
| Odor | Odorless |
| Molar Mass | 261.97 g/mol |
| Density | 2.52 g/mL |
| Melting Point | 357°C (675°F) |
| Boiling Point | 400°C (752°F) |
| Flash Point | Not applicable |
| Water Solubility | Highly soluble |
| Solubility | Soluble in water, slightly soluble in ethanol/methanol |
| Vapour Pressure | Not available |
| Vapour Density | Not available |
| pKa | Not available |
| pH | Not available |
Sodium Dichromate Safety and Hazards
Sodium bichromate poses significant safety hazards. It is highly toxic if ingested, inhaled, or absorbed through the skin. It can cause severe burns and eye damage upon contact. The compound is also classified as a potential carcinogen, capable of causing cancer. Furthermore, it is an oxidizing agent, which means it can react violently with combustible materials, increasing the risk of fires or explosions. Proper safety precautions must be taken when handling sodium bichromate, including the use of protective clothing, gloves, and eyewear. It should be stored in a secure, well-ventilated area, away from incompatible substances. In case of exposure or ingestion, immediate medical attention is crucial.
| Hazard Symbols | Corrosive, Health Hazard |
| Safety Description | Highly toxic, corrosive, carcinogenic |
| UN IDs | UN3086 |
| HS Code | 28415000 |
| Hazard Class | 6.1 |
| Packing Group | II |
| Toxicity | Very toxic |
Sodium Dichromate Synthesis Methods
There are several methods to synthesize sodium bichromate. One commonly used method is the reaction between sodium chromate (Na2CrO4) and sodium bichromate (Na2Cr2O7). Sulfuric acid (H2SO4) reacts with sodium chromate, producing sodium bichromate and water. The chemical equation for this reaction is:
2Na2CrO4 + 2H2SO4 → Na2Cr2O7 + Na2SO4 + H2O
Another method involves the oxidation of sodium chromate using a strong oxidizing agent, such as potassium permanganate (KMnO4). In this reaction, sodium chromate reacts with potassium permanganate in the presence of sulfuric acid to produce sodium bichromate, manganese dioxide (MnO2), and water.
2Na2CrO4 + 6KMnO4 + 7H2SO4 → 2Na2Cr2O7 + 6MnO2 + 7K2SO4 + 8H2O
The reaction between sodium hydroxide (NaOH) and chromium trioxide (CrO3) produces sodium bichromate. The reaction takes place in an aqueous medium and produces sodium bichromate and water.
2NaOH + CrO3 → Na2Cr2O7 + H2O
When conducting these synthesis methods, individuals must exercise caution due to the toxic and hazardous nature of sodium bichromate. Employing proper safety measures and protective equipment is imperative to ensure the well-being of the individuals involved in the process.
Sodium Dichromate Uses
Sodium bichromate has various applications across different industries. Here are some of its uses:
- Metal Plating: Electroplating processes use sodium bichromate to apply a protective and decorative coating to various metal surfaces, such as steel, aluminum, and zinc.
- Pigment Production: Sodium bichromate plays a vital role in producing pigments like chrome yellow and chrome green, which widely feature in paints, inks, and dyes.
- Wood Preservative: Sodium bichromate, with its strong oxidizing properties, preserves wood against decay, insects, and fungi, particularly in outdoor applications.
- Leather Tanning: The tanning industry employs sodium bichromate as a mordant during the leather treatment process, enhancing the color fastness and durability of leather.
- Chemical Synthesis: Sodium bichromate acts as a reagent in various chemical reactions, including the synthesis of organic compounds, oxidation reactions, and the preparation of other chromium compounds.
- Laboratory Applications: Sodium bichromate finds applications in laboratory settings for analytical testing, calibration standards, and chemical research.
- Textile Industry: Sodium bichromate improves color fastness and promotes better bonding of dyes to fabric during textile dyeing and printing processes.
- Photography: Sodium bichromate serves as a crucial component in light-sensitive emulsions and functions as an oxidizing agent in certain photographic processes.
It is important to handle sodium bichromate with care, following safety guidelines and proper disposal methods, due to its toxicity and environmental impact.
Questions:
Q: How many oxygen atoms are in 3.00 g of sodium dichromate, Na2Cr2O7?
A: There are 6.02 x 10^22 oxygen atoms in 3.00 g of sodium bichromate.
Q: How many oxygen atoms are there in 4.00 g of sodium dichromate, Na2Cr2O7?
A: There are 8.03 x 10^22 oxygen atoms in 4.00 g of sodium bichromate.
Q: How many oxygen atoms are there in 5.00 g of sodium dichromate, Na2Cr2O7?
A: There are 1.00 x 10^23 oxygen atoms in 5.00 g of sodium bichromate.
Q: How many oxygen atoms are there in 6.00 g of sodium dichromate, Na2Cr2O7?
A: There are 1.20 x 10^23 oxygen atoms in 6.00 g of sodium bichromate.
Q: How many oxygen atoms are there in 7.00 g of sodium dichromate?
A: There are 1.40 x 10^23 oxygen atoms in 7.00 g of sodium bichromate.
Q: Sodium dichromate MSDS?
A: The Material Safety Data Sheet (MSDS) for sodium bichromate provides detailed information on its properties, handling precautions, and safety measures.
Q: What could replace sodium dichromate?
A: Alternatives to sodium bichromate include other chromium compounds, such as trivalent chromium salts or non-chromium-based substances, depending on the specific application.
Q: What does sodium dichromate do?
A: Sodium bichromate is used as an oxidizing agent, wood preservative, and pigment, and in various industrial processes like metal plating and leather tanning.
Q: Can yellow chromate solution be made from sodium dichromate dihydrate?
A: Yes, yellow chromate solution can be prepared by dissolving sodium bichromate dihydrate in water.
Q: What is the formula for sodium dichromate?
A: The formula for sodium bichromate is Na2Cr2O7.
Q: Is sodium dichromate inorganic?
A: Yes, sodium bichromate is an inorganic compound.
Q: What does sodium dichromate test for?
A: Sodium bichromate can be used for testing purposes, such as assessing the presence of certain substances or monitoring specific chemical reactions.