The specific gravity of concentrated sulfuric acid is 1.84.
This value specifically applies to highly concentrated solutions, typically around 98% sulfuric acid by mass. This means that within a 100-gram sample of this solution, 98 grams are pure sulfuric acid. The specific gravity is a crucial property for understanding the density and behavior of this powerful acid.
Understanding Specific Gravity
Specific gravity is a dimensionless quantity that compares the density of a substance to the density of a reference substance, usually water at a specific temperature (often 4°C, where its density is approximately 1 g/mL). A specific gravity of 1.84 for sulfuric acid means that it is 1.84 times denser than water.
Mathematically, specific gravity (SG) is expressed as:
SG = (Density of Substance) / (Density of Reference Substance)
Because water's density is approximately 1 g/mL, the numerical value of specific gravity is often very close to the density of the substance in g/mL. Therefore, concentrated sulfuric acid has a density of approximately 1.84 g/mL.
Key Properties of Concentrated Sulfuric Acid (H₂SO₄)
Concentrated sulfuric acid is a vital industrial chemical with distinct characteristics due to its high density and reactive nature.
| Property | Value |
|---|---|
| Chemical Formula | H₂SO₄ |
| Specific Gravity | 1.84 (for 98% H₂SO₄) |
| Concentration | Typically 98% by mass |
| Appearance | Clear, colorless, viscous, oily liquid |
| Nature | Highly corrosive, strong oxidizing agent, powerful dehydrating agent |
| Boiling Point | ~337 °C (for 98% H₂SO₄) |
| Melting Point | ~10 °C (for 98% H₂SO₄) |
Why is Specific Gravity Important for Sulfuric Acid?
The specific gravity of sulfuric acid provides essential information for various applications and safety protocols:
- Quality Control: In industrial settings, specific gravity is used to quickly determine the concentration of sulfuric acid. A deviation from the expected specific gravity can indicate impurities or incorrect dilution.
- Storage and Handling: Its high density means concentrated sulfuric acid is significantly heavier than water. This impacts storage tank design, transportation logistics, and safety procedures.
- Industrial Processes: Many chemical reactions require precise concentrations of sulfuric acid. Knowing its specific gravity allows engineers to accurately measure and dose the acid in processes like fertilizer production, petroleum refining, and chemical synthesis.
- Safety: Understanding the density difference is critical for safety. If sulfuric acid is spilled into water, it will sink, and its highly exothermic dilution reaction can cause rapid boiling and splashing.
- Battery Acid: Diluted sulfuric acid is used in lead-acid batteries. The specific gravity of the electrolyte is a key indicator of the battery's state of charge.
Factors Influencing Specific Gravity
While 1.84 is the specific gravity for concentrated sulfuric acid, it can vary based on two primary factors:
- Concentration: This is the most significant factor. As the concentration of H₂SO₄ in water decreases, its specific gravity also decreases. For example, a 50% sulfuric acid solution would have a significantly lower specific gravity than a 98% solution.
- Temperature: Like most liquids, sulfuric acid expands with increasing temperature, leading to a slight decrease in its specific gravity. Conversely, cooling the acid increases its specific gravity. Standard specific gravity measurements are usually reported at a specific temperature, often 20°C or 25°C.
Understanding these factors is vital for accurate measurements and safe handling of sulfuric acid in any application.
