what is the value

Question

Atoms are very small compared to objects on the macroscopic scale. The radius of a iridium atom is 136 pm. What is this value in meters and in centimeters?  m   cm

(b) The mass of a single iridium atom is 3.19×10^-22 g. Suppose enough Ir atoms were lined up like beads on a string to span a distance of 31.8 cm ( 13 inches). How many atoms would be required?  atoms

What mass in grams of Ir would be used?  g

Could you weigh out this amount of iridium using a typical laboratory balance? _____yesno

(c) Taking the density of iridium metal to be 22.6 g/cm³, calculate the mass of metal needed to form a piece of Ir wire with the same length as the distance in b, but with a diameter of 1.00 mm. Hint: The volume of a cylinder is π times its radius squared times its height. (V = π r² h)  g

How many iridium atoms does this represent?  atoms

Answer 1

a) 136 pm = 136*10^-12 m = 136*10^-10 cm

b) 31.8 cm line will be filled with iridium atoms, one atom can cover the diameter in size 272*10^-10 cm.

Number of atoms to fill the line will be = 31.8 cm / 272*10^-10 cm = 1.169*10⁹

the g of iridium needed = 1.169*10⁹ * 3.19×10^-22 g = 3.729*10^-13g

No, because the minimum amount that can be measured in the laboratory balance is 10^-4 g.

c) 1.00 mm= 0.1 cm r = 0.05 cm

v = ∧r²h = 3.1416 * .05² cm² * 31.8 cm = 0. 249757 cm³

d = m/v

m = d * v = 22.6 g cm^-3 * 0. 249757 cm³

m = 5.644 g