Question: an oil drum weights 11.8kg. when it is filled, pentane it weighs 55.32kg. how many molecules of pentane c5h12 exist in this oil drum?
Answer:
3.64×10²⁶ molecules
Step-by-step explanation:
Applying,
n = M/M.M................... Equation 1
Where n = number of moles of pentane, M = mass of pentane, M.M = reacting mass of pentane
From the question,
Given: M = 55.32-11.8 = 43.52 kg = 43520 g
Constant: M.M of octane (C₅H₁₂) = [(12×5)+(1×12)] = 60+12 = 72 g/mol
Substitute these values into equation 1
n = 43520/72
n = 604.44 moles
Therefore,
number of molecules = n×(6.02×10²³)
number of molecules = 604.44(6.02×10²³)
number of molecules = 3.64×10²⁶ molecules