All the posts are meant for all global readers and students. It is not just for our local Sec 3, 4 and 5 students.
Do feel free to let us know your thoughts on it,
6. How does the mass of Copper (II) oxide change when it is heated in Hydrogen and in Oxygen
Mass after heating in Hydrogen , Mass after heating in Oxygen
A) decrease , decrease
B) decrease , unchanged
C) unchanged , decrease
D) unchanged , unchangedAns: B
What are your thoughts?
This is a pretty easy question. Wonder how come no students attempted on
this question.
CuO(s) are reduced back to copper with hydrogen gas:
CuO(s) + H2(g) Cu(s) + H2O(g)
As such, there is a decrease in the mass of CuO.
Note:
Hydrogen gas are common reducing agent. In this case, it has reduced CuO
from Cu(2+) to Cu(0).
No reaction between the CuO and Oxygen gas upon heating. Thus the mass
of CuO remains unchanged.
Hope this helps,
Sean
Reply