To calculate the mass of nitrogen in a fertilizer, you multiply the fertilizer's total mass by the mass percentage of nitrogen it contains. This is a straightforward calculation based on the fertilizer's composition.
Understanding Fertilizer Composition
Fertilizers are often labeled with an N-P-K ratio, representing the percentage of Nitrogen (N), Phosphorus (P), and Potassium (K) by weight. For example, a 20-10-5 fertilizer contains 20% nitrogen, 10% phosphorus, and 5% potassium.
Calculation Steps
Here's how to calculate the mass of nitrogen:
- Identify the total mass of the fertilizer. This is usually indicated on the fertilizer bag (e.g., 10 lb).
- Determine the percentage of nitrogen in the fertilizer. This is the first number in the N-P-K ratio (e.g., 20% in a 20-10-5 fertilizer).
- Convert the percentage to a decimal. Divide the percentage by 100 (e.g., 20% becomes 0.20).
- Multiply the total mass of the fertilizer by the decimal value. This gives you the mass of nitrogen in the fertilizer.
Example Calculation
Let's use the example from the provided reference: a 10.0 lb bag of 20-10-5 fertilizer.
| Step | Description | Calculation | Result |
|---|---|---|---|
| 1. Total Mass | Mass of the fertilizer bag | 10.0 lb | |
| 2. Nitrogen Percentage | Percentage of nitrogen by weight | 20.0% | |
| 3. Convert to Decimal | Divide the percentage by 100 | 20.0 / 100 | 0.20 |
| 4. Calculate Nitrogen Mass | Multiply total mass by nitrogen decimal value | 10.0 lb * 0.20 | 2.0 lb |
Therefore, a 10.0 lb bag of 20-10-5 fertilizer contains 2.0 lb of nitrogen.
In summary, according to homework.study.com, to get the mass of nitrogen in the fertilizer, we simply multiply the mass percent with the total mass of the fertilizer.
