Density Calculation Practice Answer Key (CHEM 1405)

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Solve each of the equations listed below. Use the following equations to help you:

$LaTeX: D=\frac{m}{V}$ $D=\frac{m}{V}$ mass = grams volume = cm³, mL

$LaTeX: V=l\times w\times h$ $V=l\times w\times h$

1) What is the density of an object with a mass of 60 g and a volume of 2 cm³?

$LaTeX: D=\frac{m}{V}=\frac{60g}{2cm^3}=30g/cm^3$ $D=\frac{m}{V}=\frac{60g}{2cm^3}=30g/cm^3$

2) You are given the following information: mass = 48 g; volume = 24 mL. What is the density of this substance?

$LaTeX: D=\frac{m}{V}=\frac{48g}{24mL}=2.0g/mL$ $D=\frac{m}{V}=\frac{48g}{24mL}=2.0g/mL$

3) If you have a rectangular gold brick that is 2 cm by 3 cm by 4 cm and has a mass of 48 g, what is its density?

$LaTeX: V=l\times w\times h=2cm\times3cm\times4cm=24cm^3\approx20cm^3(1S.F.)$ $V=l\times w\times h=2cm\times3cm\times4cm=24cm^3\approx20cm^3(1S.F.)$

$LaTeX: D=\frac{m}{V}=\frac{48g}{24cm^3(1SF,unrounded)}=2g/cm^3$ $D=\frac{m}{V}=\frac{48g}{24cm^3(1SF,unrounded)}=2g/cm^3$

4) Bob, who weights 150 pounds, found a rock. What is the density of a rock if its mass is 36 g and its volume is 12 mL?

$LaTeX: D=\frac{m}{V}=\frac{36g}{12mL}=3.0g/mL$ $D=\frac{m}{V}=\frac{36g}{12mL}=3.0g/mL$

5) If a block of wood has a density of 0.6 g/cm³ and a mass of 120 g, what is its volume?

$LaTeX: 120g\times(\frac{1cm^3}{0.6g})=200g$ $120g\times(\frac{1cm^3}{0.6g})=200g$

6) What is the mass of an object that has a volume of 34 cm³ and a density of 6 g/cm³?

$LaTeX: 34cm^3\times(\frac{6g}{1cm^3})=200g$ $34cm^3\times(\frac{6g}{1cm^3})=200g$

7) What is the density of a 75 g block of wood measuring 12cm x 8 cm x 9 cm?

$LaTeX: V=l\times w\times h=12cm\times8cm\times9cm=864cm^3\approx900cm^3(1S.F.)$ $V=l\times w\times h=12cm\times8cm\times9cm=864cm^3\approx900cm^3(1S.F.)$

$LaTeX: D=\frac{m}{V}=\frac{75g}{864cm^3(1SF,unrounded)}=0.09g/cm^3$ $D=\frac{m}{V}=\frac{75g}{864cm^3(1SF,unrounded)}=0.09g/cm^3$

8) What is the density of a 22 kg boy who’s volume is 6,400 mL?

$LaTeX: 22kg\times(\frac{1000g}{1kg})=22,000g$ $22kg\times(\frac{1000g}{1kg})=22,000g$

$LaTeX: D=\frac{m}{V}=\frac{22,000g}{6,400mL}=3.4g/mL$ $D=\frac{m}{V}=\frac{22,000g}{6,400mL}=3.4g/mL$

9) What is the mass of 300 mL of a liquid with a density of 2.3 g/mL?

$LaTeX: 300mL\times(\frac{2.3g}{1mL})=700g$ $300mL\times(\frac{2.3g}{1mL})=700g$

10) What is the volume of a substance with a mass of 0.35 g and a density of 0.9 g/cm³?

$LaTeX: 0.35g\times(\frac{1cm^3}{0.9g})=0.4cm^3$ $0.35g\times(\frac{1cm^3}{0.9g})=0.4cm^3$