Some solid CaO in a test tube picks up water vapor from the surroundings to change

completely to Ca(OH). An observed total initial weight (CaO + test tube) of 10.860 g
goes eventually to 11.149 g. What is the weight of the test tube?

1 answer

CaO + H2O ==< Ca(OH)2

11.149 g = TT + CaO + H2O
-10.860 g = TT + CaO
-----------
0.289 g = H2O added.

Using stoichiometry, convert g H2O tog CaO. Then
10.860 g = TT + CaO
-xxxxxx g = CaO
----------
xxxxxxx g = TT
Post your work if you get stuck.