chem math question

Question

Calculate the mass of each of the following:

 

(a) a sphere of gold with a radius of 12.1 cm; the density of gold is 19.3 g/cm³.) Enter your answer in scientific notation.

(b) a cube of platinum of edge length 0.047 mm (density = 21.4 g/cm³). Enter your answer in scientific notation.

(c) 39.7 mL of ethanol (density = 0.798 g/mL). Answer in grams.

Answer 1

a)

V = (4/3)*pi*12.1^3 = 7.43E3 cm^3

m = V * d = 7.43E3 cm^3 * 19.3 g/cm^2 = 1.43E5 g

b)

0.047mm = 4.7E-2mm = 4.7E-3 cm

V = (4.7E-3 cm )^3 = 1.0E-7 cm^3

m = V * d = 1.0E-7 cm^3 * 21.4 g/cm^3 = 2.1E-6 g

c)

m = V * d = 39.7 mL * 0.798 g/mL = 3.17E1 g