A student needs half a mole of copper metal to make a set of electrodes. Using the relative atomic mass of copper, Ar(Cu) = 64, what mass of copper should b...
Question 1 Report
A student needs half a mole of copper metal to make a set of electrodes. Using the relative atomic mass of copper, Ar(Cu) = 64, what mass of copper should be weighed out for this experiment?
Answer Details
The mass needed is 32 g. Mass = moles × Ar = 0.5 × 64 = 32 g, which makes sense because half a mole must weigh half of the molar mass.
Choosing 64 g weighs out a full mole and ignores the word half. Choosing 128 g multiplies by 2 instead of by 0.5, a very common slip when the fraction is written as a word rather than a decimal. Choosing 16 g quarters the molar mass, treating half a mole as half of a half. Writing the numbers into mass = n × Ar before calculating stops all three errors, and gives about 3.01 × 1023 copper atoms.
Download The App On Google Playstore
Everything you need to excel in your exams
