If 18 lb of soda ash are mixed with 75 gal of water, what will the percentage of soda ash in the resulting slurry?

• A. 23.35%
• B. 2.9%
• C. 0.28%
• D. 2.8%

Answer: (D)

In a slurry, the percentage is usually by weight, so you compare the mass of solid to the total mass of the mixture. Convert the water volume to mass using water’s density: 75 gallons × 8.34 lb/gal ≈ 625.5 lb. The total mass is 625.5 lb + 18 lb = 643.5 lb. The weight percent of soda ash is 18 / 643.5 × 100 ≈ 2.80%. Therefore, the soda ash is about 2.8% of the slurry by weight.