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Sodium dihydrogen phosphate, commonly known as monobasic sodium phosphate, is an inorganic compound.
- Another name for sodium dihydrogen phosphate is Monosodium phosphate.
- Its chemical formula is NaH2PO4.
- Sodium phosphate is a group of chemical compounds.
- The phosphate atom also carries three more atoms.
- When it has three hydrogens, it forms phosphoric acid.
- Similarly, one hydrogen and two sodium produce disodium hydrogen phosphate, whereas three sodium yields trisodium phosphate.
- When two hydrogens and one sodium are present, the compound is known as sodium dihydrogen phosphate.
- It is also a glycerol derivative formed by treating mono- and diglycerides produced from edible sources with phosphorus pentoxide.
- After that, sodium carbonate is used to neutralize the pH.
- It is soluble in water but insoluble in alcohol.
| Table of Content |
Key Terms: Sodium dihydrogen phosphate, Monobasic sodium phosphate, Sodium cation, Dihydrogen phosphate anion, Sodium carbonate, Melting point, Boiling point
What is Sodium Dihydrogen Phosphate?
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Sodium dihydrogen phosphate is an inorganic monobasic sodium phosphate compound with the chemical formula NaH2PO4.
- Sodium dihydrogen phosphate is a glycerol derivative produced by reacting mono and diglycerides taken from edible sources with phosphorus pentoxide and neutralizing with sodium carbonate.
- Sodium dihydrogen phosphate is a soluble form of phosphate that can be given intravenously.
- The other names of sodium dihydrogen phosphate are Monobasic sodium phosphate and Monosodium phosphate (MSP).
| Sodium Dihydrogen Phosphate | |
|---|---|
| Chemical Formula | NaH2PO4 |
| 119.98 g/mol | |
| Density | 2.36 g/cm3 |
| pKa | 6.8 – 7.2 |
| Melting point | 212 oC |
Also check:
| Related Concepts | ||
|---|---|---|
| Ammonium phosphate | Calcium Sulphate | Etard reaction |
| Chemical Tranquillisers | Barium Carbonate | Californium |
Sodium Dihydrogen Phosphate Structure
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The structure of sodium dihydrogen phosphate is shown below
Physical Properties of Sodium Dihydrogen Phosphate - NaH2PO4
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The following are the physical properties of sodium dihydrogen phosphate
| Physical properties of Sodium Dihydrogen Phosphate | |
|---|---|
| Odour | Odourless |
| Appearance | White powder or crystals |
| pH | 8.0 and 11.0 |
| Complexity | 61.9 |
| Solubility in water | Soluble in water; insoluble in alcohol |
| IUPAC name | Sodium dihydrogen phosphate |
| Boiling point | 158 oC |
| Melting point | 212 oC |
Chemical Properties of Sodium Dihydrogen Phosphate
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The following are the chemical properties of sodium dihydrogen phosphate
Reaction with Bases
Sodium dihydrogen phosphate reacts with bases such as sodium hydroxide, producing sodium hydrogen phosphate and water.
NaH2PO4 + NaOH → Na2HPO4 + H2O
Reaction with Acids
When sodium dihydrogen phosphate reacts with an acid, such as hydrochloric acid, it produces phosphoric acid and sodium chloride.
NaH2PO4 + HCl → H3PO4 + NaCl
Uses of Sodium Dihydrogen Phosphate
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The uses of sodium dihydrogen phosphate are as follows
- It has a wide range of uses in the water and food industries.
- It is used as an emulsifier in processed cheese, for example.
- In baked foods, it also acts as a thickening and leavening agent.
- It keeps the pH of processed meals in check.
- It is also used extensively in medications.
- They provide sodium phosphate intravenously to replace electrolytes.
- It can also be used orally or rectally as a laxative.
- It also acts as a urinary acidifier and prevents kidney stones when taken orally.
- It is used in medicine to alleviate constipation and prepare the intestines for therapeutic procedures.
- It is used in some regions to identify the presence of magnesium ions in salts.
- It is found in toothpaste, evaporated milk, and animal feed, among other things.
- It also acts as a thickener and emulsifier in this application.
- In a variety of meals, the chemical is often employed as a sequestrant.
Also check:
| Relevant Topics | ||
|---|---|---|
| Lewis acids | Schottky Defect | Carboxylic Acids |
| Gatterman reaction | Reimer Tiemann reaction | Combined Gas Law |
Things to Remember
- Sodium dihydrogen phosphate is an inorganic compound.
- The other names of sodium dihydrogen phosphate are Monobasic sodium phosphate and Monosodium phosphate.
- Its chemical formula is NaH2PO4.
- It is soluble in water but insoluble in alcohol.
- When it reacts with bases, such as sodium hydroxide, it produces sodium hydrogen phosphate and water.
- When it reacts with an acid, such as hydrochloric acid, it produces phosphoric acid and sodium chloride.
Sample Questions
Ques. What is Sodium Dihydrogen Phosphate? (2 Marks)
Ans. Sodium Dihydrogen Phosphate is a chemical compound that is extensively used in industry. Monobasic sodium phosphate, or Monosodium phosphate, is another name for it.
Ques. Is sodium dihydrogen phosphate an acid or base? (2 Marks)
Ans. The compound NaH₂PO₄, or Sodium Dihydrogen Phosphate, is a salt that can behave as an acid or basic depending on its environment. This is due to its amphoteric properties.
Ques. What is another name for Sodium hydrogen phosphate? (1 Mark)
Ans. The other names of sodium dihydrogen phosphate are Monobasic sodium phosphate and Monosodium phosphate.
Ques. What is the pH of sodium dihydrogen phosphate? (1 Mark)
Ans. The pH value of sodium dihydrogen phosphate is 8.0 and 11.0.
Ques. Is sodium dihydrogen phosphate solid or liquid? (1 Mark)
Ans. Sodium dihydrogen phosphate appears in the form of white powder or crystals.
Ques. Explain how Sodium Dihydrogen Phosphate is used in identifying magnesium ions. (2 Marks)
Ans. A white precipitate is formed when magnesium ions are present in a solution and Sodium Dihydrogen Phosphate is added to ammonium chloride and ammonium hydroxide in an aqueous solution.
Ques. Write the formula of Sodium Dihydrogen Phosphate. (3 Marks)
Ans. The Formula of Sodium Dihydrogen Phosphate is NaH2PO4
Ques. List the properties of Sodium Dihydrogen Phosphate. (5 Marks)
Ans. Sodium Dihydrogen Phosphate has the following properties:
- The molecular weight of sodium dihydrogen phosphate is 120 g/mol.
- 2.36 g/cm3 is the density.
- Sodium Dihydrogen Phosphate comes in powdered or crystalline form and is white in color.
- The refractive index of sodium dihydrogen phosphate is 1.463.
- NaH2PO4 is the formula for Sodium Dihydrogen Phosphate.
- When sodium dihydrogen phosphate is heated above 170°C, sodium acid pyrophosphate is formed.
Ques. How can we calculate the buffer capacity? (2 Marks)
Ans. The buffer capacity of Potassium Dihydrogen Phosphate is calculated using the same formula used to find its pH value. The formula is as follows:
Buffer capacity = pKa + log10 ([A-]/[HA])
Where [A-] stands for the concentration of the base of the buffer,
[HA] stands for the concentration of acid in buffer,
pKa stands for the dislocation constant of the acid.
Ques. Let’s have 600 ml of a sodium phosphate buffer of concentration c = 0.25 mol/l and the ratio acid: base is 2:3. Next, we add 150 ml of HCl, c = 0.2 mol/l. How much does the pH change after this addition? (pKa of sodium dihydrogen phosphate is 7.21) (5 Marks)
Ans. In order to calculate the pH of this buffer before and after the addition of HCl, we need to know the ratio of acid: to base for both conditions. The ratio is given for the original buffer as 2:3, so we can easily use the Henderson-Hasselbalch equation to calculate the original pH:
pH = pKa + log 3/2 = 7.21 + log 1.5 = 7.21 + 0.17609 = 7.39.
Next, we need to consider how the ratio of acid: base changes following the addition of HCl. The strong acid actually titrates the basic component of the buffer, converting it into an acidic component:
HCl + Na2HPO4 → NaH2PO4 + NaCl
Before the addition of HCl:
Number of moles for total phosphate: 0.6 × 0.25 = 0.15 mol
NaH2PO4: 0.15 × 2/5 = 0.06 mol
NaH2PO4: 0.15 × 3/5 = 0.09 mol
After addition of HCl 0.15 × 0.2 = 0.03 mol:
Number of moles for total phosphate: 0.6 × 0.25 = 0.15 mol
NaH2PO4: 0.06 mol + 0.03 mol = 0.09 mol
Na2HPO4: 0.09 mol − 0.03 mol = 0.06 mol
The new ratio of acid: base is 0.09: 0.06, i.e. 3: 2.
The resulting pH is:
pH = pKa + log 2/3 = 7.21 + log 0.6667 = 7.21 − 0.17609 = 7.03
The pH change (effect of addition): pH = 7.39 − 7.03 = − 0.36
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