1. **State the problem:** Calculate the annual hydrogen fluoride (HF) emissions in tons per year (t/y) from a metal production process. 2. **Given data:** - Production rate: 42,000 tons per year - Operating hours: 8,760 hours per year - Emission factor: 2.32 lbs HF per 100 lbs of metal - Conversion factor: 2,000 lbs per ton 3. **Formula used:** $$\text{Emissions (t/y)} = \frac{\text{Production (tons)} \times \text{Operating hours} \times \text{Emission factor (lbs HF/100 lbs)}}{\text{Conversion factor (lbs/ton)} \times 100}$$ 4. **Calculate emissions:** $$\text{Emissions} = \frac{42,000 \times 8,760 \times 2.32}{2,000 \times 100}$$ 5. **Simplify numerator and denominator:** $$\text{Emissions} = \frac{42,000 \times 8,760 \times 2.32}{200,000}$$ 6. **Calculate numerator:** $$42,000 \times 8,760 = 367,920,000$$ $$367,920,000 \times 2.32 = 853,574,400$$ 7. **Divide numerator by denominator:** $$\text{Emissions} = \frac{853,574,400}{200,000}$$ 8. **Simplify fraction by canceling zeros:** $$\text{Emissions} = \frac{\cancel{853,574,400}}{\cancel{200,000}} = 4,267.872$$ 9. **Final answer:** The annual HF emissions are approximately **4,267.87 tons per year**. This calculation shows how to convert production and emission factors into total emissions using unit conversions and multiplication.