A student is asked to find the mass corresponding to of ( CuSO _ 4 5 H _ 2 O ) but…
CHEMISTRY · Single correct · A Level · Chemistry · Amount of substance · Amount of substance
Problem
A student is asked to find the mass corresponding to 0.100mol of CuSO4⋅5H2O but mistakenly uses the molar mass of anhydrous CuSO4 instead. Which statement best describes how the student’s numerical result compares with the correct value?
(a) The calculated mass is higher because omitting the waters of hydration increases the molar mass used.
(b) The calculated mass is lower because the contribution of the water molecules was omitted.
(c) The calculated mass is the same because any mass difference cancels when the amount is expressed in moles.
(d) The comparison cannot be made without knowing exactly how many water molecules are present in the hydrate sample.