How many atoms are present in a 9.78-m lenth of 20-gauge copper wire? A 20-guage copper wire has a diameter of 0.03196 in. and the density of copper is 8.92 g/cm^3
help?
2007-09-18 06:55:53 · 2 answers · asked by mike g 1 in Science & Mathematics ➔ Chemistry
you gotta find the mass first
mass = pi*r^2*length*density = 3.14 * (0.03196 in * 2.54 cm/in /2)^2*9.78*100cm/m*8.92 = 45.16 grams
so u have 45.16 gr * 6.02E25 = 2.719 E25 atoms
2007-09-18 07:28:24 · answer #1 · answered by vasilios s 2 · 0⤊ 0⤋
1 inch =2.54cm so 0.03196 i =0.03196*2.54 =0.0811784cm
the section is pi*(0.0811784)^2/4 =5.175*10^-3cm^2
volume in cm =978*5.175*10^-3=5.062cm^3
weight is 5.062*8.92=45.15g
the atomic mass of copper is 63.55g
so 45.15/63.55=0.705 atome-gram
an atom gram consists of 6.022*10^23 atoms so
number 4.248*10^23 atoms
2007-09-18 14:28:31 · answer #2 · answered by maussy 7 · 0⤊ 0⤋