Question 259794

A chemist is performing a reaction as follows,

Co(NO.)3 (aq) + (NHA) 2S (aq) > Co2S3 (s) + NHANO3 (aq)

Upon completion of the reaction the chemist measured the precipitate (solid) formed by extracting it and drying

it. Upon drying the precipitate, he was not satisfied by the reading he obtained in the first round of measurement

in which he got a reading of 75mg, thus he measured the precipitate 2 more times and recorded the following

readings on the weighing scale 0.078g and 7.6x 10-*kg. Using the given information calculate the percentage

error that has been recorded in these readings. In doing so, the chemist has also forgot to balance the above

chemical reaction, which you need to balance and help him out.