FE Chemical Solids Handling Practice Problems

The current FE Chemical specification assigns 3-5 of the 110 exam questions to Solids Handling. Form A contains 3 original problems in this area. The sample below is published in full, with the same worked-solution format used throughout the book.

Free sample problem

A powder has equal mass fractions of 100 micrometer and 400 micrometer particles of equal density and shape. Sauter mean diameter d32=1/sum(w_i/d_i) is most nearly:

(A)100 micrometer
(B)160 micrometer
(C)250 micrometer
(D)400 micrometer

Show worked solution

Answer: (B)

d32=1/(0.5/100+0.5/400)=160 micrometres.

The surface-volume mean weights inverse diameter by mass fraction for equal density.

1/ d_{32} = \sum w_{i} / d_{i}

The inverse mean is 0.00625 per micrometre.

d_{32} = 1/ (0.005 + 0.00125) = 160 μ m

FE Reference Handbook — Solids Handling: Particle Size Distributions

Why the other choices appear

(A)Using only the fine fraction ignores coarse particles.
(C)Taking an arithmetic mean does not give surface-volume mean diameter.
(D)Using only the coarse fraction ignores the added surface from fines.

The complete FE Chemical practice exam contains 3 problems in this area and 110 problems overall, with an answer key, full solutions, and a score sheet by knowledge area.

Free FE Chemical problems in the other knowledge areas

Mathematics · Probability and Statistics · Engineering Sciences · Materials Science · Chemistry and Biology · Fluid Mechanics and Dynamics · Thermodynamics · Material and Energy Balances · Heat Transfer · Mass Transfer and Separation · Chemical Reaction Engineering · Economics · Process Design · Process Control · Safety, Health, and Environment · Ethics and Professional Practice

Retaking this exam? The FE exam retake guide turns the NCEES diagnostic report into an area-by-area plan.