1) A spherical ball of lead has a diameter of 4.00 cm. What is the mass of the sphere if lead has a density of 11.34 g/cm3. (The volume of a sphere is (4/3) πr3 where r is the radius.)
_______g
2) An experiment requires 15.1 g of cyclohexane, whose density at 25°C is 0.7781 g/mL. What volume of cyclohexane should be used?
_________ml
3)A cylindrical rod formed from silicon is 16.3 cm long and has a mass of 2.11 kg. The density of silicon is 2.33 g/cm3. What is the diameter of the cylinder? (The volume of a cylinder is given by πr2h, where r is the radius, and h is its length.)
________cm
4) After the label fell off a bottle containing a clear liquid believed to be benzene, a chemist measured the density of the liquid to verify its identity. A 25.0-mL portion of the liquid had a mass of 21.95 g. A chemistry handbook lists the density of benzene at 25°C as 0.8787 g/mL. Is the calculated density in agreement with the tabulated value?
A - Yes B - No
PLEASE HELP!!
Answers (1)
1.)
Solve for volume:
V = (4/3) π r^3
V = (4/3) π (2 cm)^3
V = 33.5 cm^3
Find mass:
Density = mass / Volume
(11.34 g/cm^3) = mass / (33.5 cm^3)
mass = 379.89 g -- ANSWER!
2.)
Density = mass / Volume
0.7781 g/mL = (15.1 g) / (Volume)
Volume = 19.406 mL -- Answer!
3.)
Volume = mass / Density
V = (2.11 kg * 1,000 g / 1 kg) / (2.33 g/cm^3) = 905.58 cm^3
Find diameter (first find radius):
V = π r^2 h
radius = sqrt(V / π * h)
r = sqrt( 905.58 cm^3 / π * (16.3 cm) )
r = 4.205 cm
Diameter = Radius * 2 = 4.205 cm * 2 = 8.41 cm -- ANSWER
4.)
D = m / V = 21.95 g / 25 mL = 0.878 g/mL
Answer is B - No
(The calculated density was 0.878 g/mL NOT 0.8787 g/mL)
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I hope you understand and do not just copy. These are very important concepts.