Question

(a) Calculate the density of a 374.5-g sample of copper if it has a volume of 41.8 cm3. (b) A student needs 15.0 g of ethanol for an experiment. If the density of ethanol is 0.789 g>mL, how many milliliters of ethanol are needed? (c) What is the mass, in grams, of 25.0 mL of mercury 1density=13.6 g>mL2?

Answer 1

Answer:

For a: The density of the sample of copper is $8.96g/cm^3$

For b: The volume of ethanol needed is 19.0 mL

For c: The mass of mercury is 340. grams

Explanation:

To calculate density of a substance, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$      ......(1)

• For a:

Mass of copper = 374.5 g

Volume of copper = $41.8cm^3$

Putting values in equation 1, we get:

$\text{Density of copper}=\frac{374.5g}{41.8cm^3}\\\\\text{Density of copper}=8.96g/cm^3$

Hence, the density of the sample of copper is $8.96g/cm^3$

• For b:

Mass of ethanol = 15.0 g

Density of ethanol = 0.789 g/mL

Putting values in equation 1, we get:

$0.789g/mL=\frac{15.0g}{\text{Volume of ethanol}}\\\\\text{Volume of ethanol}=\frac{15.0g}{0.789g/mL}=19.0mL$

Hence, the volume of ethanol needed is 19.0 mL

• For c:

Volume of mercury = 25.0 mL

Density of mercury = 13.6 g/mL

Putting values in equation 1, we get:

$13.6g/mL=\frac{\text{Mass of mercury}}{25.0mL}\\\\\text{Mass of mercury}=(13.6g/mL\times 25.0mL)=340.g$

Hence, the mass of mercury is 340. grams