Unit Converter (Chemistry-Focused)
Convert between common units used in general chemistry—fast and accurate. Supports length (nm, cm, m), mass (g, kg, lb), volume (mL, L), pressure (atm, mmHg, kPa), energy (J, kJ, cal), and temperature (°C, K, °F).
Background
This converter uses exact or standard factors favored in chemistry and physics. Examples: 1 atm = 101 325 Pa (exact), 1 bar = 100 000 Pa (exact), 1 cal = 4.184 J (thermochemical), and 1 L = 1000 mL. Temperature conversions are handled with affine formulas (°C↔K, °C↔°F).
How to use the converter
1) Pick the quantity (length, mass, volume, pressure, energy, temperature).
2) Enter a value, then choose from and to units.
3) Click Convert (or press Enter) to get the answer and the factor used.
4) Use Swap to flip units and auto-recompute.
Chemistry-friendly notes
- Pressure: 1 atm = 101 325 Pa (exact); 1 bar = 100 000 Pa (exact).
- Energy: 1 cal = 4.184 J (thermochemical convention), 1 kcal = 4184 J.
- Volume: 1 mL = 1 cm³; 1 L = 1000 mL = 10⁻³ m³.
- Temperature uses affine formulas (offset + scale), not a single factor.
Example Problems & Step-by-Step Solutions
Example 1 (Pressure)
Convert 0.980 atm to mmHg.
- Use 1 atm = 760 mmHg (standard convention).
- 0.980 × 760 = 744.8 mmHg.
Example 2 (Energy)
Convert 3.50 kJ to calories.
- 1 cal = 4.184 J ⇒ 1 kJ = 1000 J = 1000 / 4.184 cal ≈ 239.006 cal.
- 3.50 kJ × 239.006 ≈ 836.5 cal.
Example 3 (Temperature)
Convert 25 °C to K and °F.
- K = °C + 273.15 ⇒ 25 + 273.15 = 298.15 K.
- °F = (9/5)·°C + 32 ⇒ (9/5)·25 + 32 = 77 °F.
Frequently Asked Questions
Q: What’s the difference between mmHg and Torr?
1 Torr is defined as exactly 1/760 atm. 1 mmHg is very close (based on mercury column definition); for most general chemistry problems they’re treated as interchangeable.
Q: Which calorie do you use?
The thermochemical calorie: 1 cal = 4.184 J. (Nutrition “Calorie” is 1 kcal.)
Q: Are these factors precise enough for exams?
Yes for Gen Chem. When your instructor specifies different constants, match their values.
