Question

How many molecules are in each sample?

Answer 1

Answer:

To find the number of molecules first find the number of moles.

number of moles (n) = mass / molar mass (M)

then use the formula

N = n × L

where n = number of moles

N = number of entities

L = Avogadro's constant = 6.02 × 10^23entities to find the number of molecules

A. 4.9 g H2O

m = 4.9g

M = (2*1)+(16×1) = 2 + 16 = 18g/mol

n = 4.9/18 = 0.272mol

N = 0.272 × 6.02 × 10^23

= 1.6374*10^23 molecules of H2O

B. 54.4g of N2

m = 54.4g

M(N2) = 14×2 = 28g/mol

n = 54.4/28 = 1.942mol

N = 1.942 * 6.02*10^23

= 1.1690*10^24 molecules of N2

C. 89 g CCI4

m = 89g

M(CCl4) = 12 + (35.5 × 4) = 154g/mol

n = 89/154 = 0.577mol

N = 0.577 × 6.02 × 10^23

= 3.473*10^23 molecules of CCl4

D. 11 g C6H12O6

m = 11g

M(C6H12O6) = (12×6)+(12×1)+(16×6) =

180g/mol

n = 11/180 = 0.0611mol

N = 0.0611 × 6.02×10^23

= 3.678*10^22 molecules of C6H12O6

Hope this helps