A technician prepares four separate samples to calibrate a mass balance
CHEMISTRY · Multi-part · A Level · Chemistry · Amount of substance · Amount of substance
Problem
A technician prepares four separate samples to calibrate a mass balance. The masses and chemical identities of the samples are listed below.
• 18.0 g of liquid water, H₂O (ℓ)
• 30.0 g of carbon dioxide, CO₂ (g)
• 65.0 g of copper metal, Cu (s)
• 58.5 g of sodium chloride, NaCl (s)
Each sample is pure and dry.
(a) Calculate the amount of substance, in moles, present in each of the four samples. Show all work, including units.
(b) Using your results from part (a), rank the samples from the greatest to the fewest number of chemical entities (atoms, molecules, or formula units, as appropriate).
(c) Identify which sample contains the greatest number of oxygen atoms. Support your answer with appropriate reasoning or calculations.