During a heavy monsoon shower a circular city of radius receives of uniform rainfall in
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
During a heavy monsoon shower a circular city of radius 20km receives 2.0cm of uniform rainfall in 24h. The density of water is 1.0×103kgm−3. Avogadro’s number is 6.02×1023mol−1 and the molar mass of water is 18gmol−1.
Use the data to make an order-of-magnitude estimate of how many water molecules fall on the city during the shower by following the steps below.
(i) Calculate the total volume of rainwater that falls on the city.
(ii) Determine the mass of this volume of water.
(iii) Estimate the total number of water molecules involved and write the result in scientific notation.
(iv) State the order of magnitude of your answer and identify two assumptions that could most affect its accuracy.