A mole fraction calculator is a tool used to determine the proportion of a specific component within a mixture in chemistry, particularly in solution chemistry and thermodynamics.
For instance, consider a solution of ethanol and water:
- 2 moles of ethanol
- 3 moles of water
The mole fraction of ethanol would be:
2 / (2 + 3) = 0.4 or 40%Mole Fraction Calculator
| Mixture Components | Moles | Mole Fraction |
|---|---|---|
| H₂ | 3 | 0.429 |
| O₂ | 2 | 0.286 |
| N₂ | 2 | 0.286 |
| Total | 7 | 1.000 |
| Solution Components | Moles | Mole Fraction |
|---|---|---|
| Ethanol | 1 | 0.167 |
| Water | 5 | 0.833 |
| Total | 6 | 1.000 |
| Alloy Components | Moles | Mole Fraction |
|---|---|---|
| Copper | 2 | 0.400 |
| Zinc | 1 | 0.200 |
| Nickel | 2 | 0.400 |
| Total | 5 | 1.000 |
Mole Fraction Formula
The mole fraction formula is expressed as:
X_i = n_i / n_totalWhere:
X_iis the mole fraction of component in_iis the number of moles of component in_totalis the total number of moles in the mixture
This formula is versatile and applicable to various scenarios in chemistry and chemical engineering. For example, in a gas mixture of nitrogen and oxygen:
- 3 moles of N₂
- 1 mole of O₂
The mole fraction of nitrogen would be:
X_N₂ = 3 / (3 + 1) = 0.75 or 75%How do you calculate mole fraction?
Calculating mole fraction involves a step-by-step process:
Identify all components in the mixture
Determine the number of moles for each component
Calculate the total number of moles
Divide the moles of each component by the total moles
Let’s apply this to a more complex example:
A solution contains:
- 2 moles of NaCl
- 3 moles of KCl
- 5 moles of H₂O
Step 1: Components identified (NaCl, KCl, H₂O) Step 2: Moles determined (2, 3, 5 respectively) Step 3: Total moles = 2 + 3 + 5 = 10 Step 4:
- X_NaCl = 2 / 10 = 0.2
- X_KCl = 3 / 10 = 0.3
- X_H₂O = 5 / 10 = 0.5
This calculation demonstrates how mole fractions always sum to 1, reflecting the entire composition of the mixture.
How to convert from mole ratio to mole fraction?
Converting between them is straightforward:
Express the mole ratio as a fraction
Sum all parts of the ratio
Divide each part by the sum
Consider a mole ratio of C:H:O as 1:2:1 in a compound.
Ratio as fractions: 1/4 : 2/4 : 1/4
Sum of parts: 1 + 2 + 1 = 4
Mole fractions:
X_C = 1/4 = 0.25
X_H = 2/4 = 0.50
X_O = 1/4 = 0.25
References
- National Institute of Standards and Technology (NIST): Thermodynamics Research Center
- Royal Society of Chemistry: Mole Fraction
- American Chemical Society: Principles of General Chemistry
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