Questions: 7) Find the mass of 250.0 mL of benzene. The density of benzene is 0.8765 g / mL. 8) A block of lead has dimensions of 4.50 cm by 5.20 cm by 6.00 cm. The block has a mass of 1587 g. From this information, calculate the density of lead.

Solution Steps

To find the mass of benzene, we use the formula: \[ \text{mass} = \text{density} \times \text{volume} \] Given:

• Density of benzene, \( \rho = 0.8765 \, \text{g/mL} \)
• Volume of benzene, \( V = 250.0 \, \text{mL} \)

Substitute the values into the formula: \[ \text{mass} = 0.8765 \, \text{g/mL} \times 250.0 \, \text{mL} = 219.125 \, \text{g} \]

To find the volume of the lead block, we use the formula for the volume of a rectangular prism: \[ \text{volume} = \text{length} \times \text{width} \times \text{height} \] Given:

• Length, \( l = 4.50 \, \text{cm} \)
• Width, \( w = 5.20 \, \text{cm} \)
• Height, \( h = 6.00 \, \text{cm} \)

Substitute the values into the formula: \[ \text{volume} = 4.50 \, \text{cm} \times 5.20 \, \text{cm} \times 6.00 \, \text{cm} = 140.4 \, \text{cm}^3 \]

To find the density of lead, we use the formula: \[ \text{density} = \frac{\text{mass}}{\text{volume}} \] Given:

• Mass of the lead block, \( m = 1587 \, \text{g} \)
• Volume of the lead block, \( V = 140.4 \, \text{cm}^3 \)

Substitute the values into the formula: \[ \text{density} = \frac{1587 \, \text{g}}{140.4 \, \text{cm}^3} = 11.31 \, \text{g/cm}^3 \]

Final Answer