Assume that the formula of copper(II)oxide is CuO.Predict the mass of Cu that should remain after the reaction

Question

Sample data: mass of empty tube=41.80g;mass of tube plus oxide=43.00g;mass of tube after reduction=42.78g

Answer 1

(tube+oxide) - (tube) = 43.00g - 41.80g = 1.20g CuO

(tube>reduction) - (tube) = 42.78g - 41.80g = 0.98g Cu

Atomic weights: Cu=63.5  O=16  CuO=79.5

1.20gCuO x 1molCuO/79.5gCuO x 1molCu/1molCuO x 63.5gCuO/1molCu = 0.96g Cu should remain after reaction

There was actually 0.98g Cu left. Apparently the reduction was incomplete. Still a little O left in the Cu.