Question

An alloy of iron (54.7%), nickel (45%) and manganese (0.3%) has, a density of $8.17g/c{m}^3$ . How many iron atoms are there in a block of alloy measuring $10cm\times 20cm\times 15cm$ ?

Answer 1

Volume of the block of alloy $=10\times 20\times 15c{m}^3$
$=3000c{m}^3$
Mass of the block $=3000\times 8.17g=24510g$
Mass of iron in the block $=\frac{54.7}{100}\times 24510=13406.97g$
Number of iron atoms in the block $=\frac{Mass}{Atomicmass}\times 6.023\times {10}^{23}$
$=\frac{13406.97}{56}\times 6.023\times {10}^{23}$
Atomic mass $=1.442\times {10}^{26}$