Final answer:
The mass of the mystery substance is 117.498 g, its density is 2.665 g/mL, and the percentage error compared to the actual density of 2.34 g/mL is approximately 13.889%.
Step-by-step explanation:
To calculate the mass of the mystery substance, subtract the mass of the beaker from the combined mass of the beaker and the substance. The mass of the mystery substance is 287.888 g (combined mass) minus 170.39 g (beaker mass), which equals 117.498 g.
Next, to find the density of the mystery substance, divide its mass by its volume. The density is 117.498 g (mass) divided by 44.1 mL (volume), which equals approximately 2.665 g/mL.
Finally, to determine the percentage error in the density measurement, subtract the actual density from the measured density, divide by the actual density, and then multiply by 100. The percentage error is |(2.665 g/mL - 2.34 g/mL) / 2.34 g/mL| × 100, which equals approximately 13.889%.