A student reacted black copper(II) oxide with warm dilute sulfuric acid to make copper(II) sulfate. When the reaction was over, some black solid had not dis...
Question 1 Report
A student reacted black copper(II) oxide with warm dilute sulfuric acid to make copper(II) sulfate. When the reaction was over, some black solid had not dissolved. Fig. 1.1 shows the apparatus the student used to separate this excess black solid from the aqueous copper(II) sulfate. Three parts of the apparatus are labelled A, B and C.
(a) Name the parts of the apparatus labelled A, B and C on Fig. 1.1. [3]
(b) Name the solid that is left behind as the residue. [1]
(c) State the name of the salt that is present in the filtrate. [1]
Answer Details
This question tests naming filtration apparatus and identifying the residue and filtrate when excess insoluble solid is removed after making a soluble salt.
(a) The labelled parts are: A = filter funnel [1]; B = filter paper (the folded cone inside the funnel) [1]; C = conical flask (a beaker is accepted) that collects what passes through [1]. [3]
(b) The excess black solid trapped on the paper as the residue is the unreacted copper(II) oxide [1] (it was added in excess so that all the acid reacted).
(c) The salt in the blue filtrate that passes through is copper(II) sulfate [1], formed by \(CuO + H_2SO_4 \rightarrow CuSO_4 + H_2O\).
Exam tip: in filtration the residue stays on the paper (insoluble) and the filtrate passes through (the dissolved salt).
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