[Ohm]

Well.. i have a little question here ...

CuO + 2HCl ---- > CuCl2 + H2O

What mass of copper ( II ) Oxide is needed to produce 9g of water ?

My attempt at a solution :

Molar Mass of water = ( 1 x 2 ) + 16 = 18.00g
18g of water require ( 64 + 16 ) g of CuO
9g of water require 9 / 18 x ( 64 + 16 )g = 40g of CuO.

Apparently, my answer was wrong and i dont know why...

[opti384]

To me there seems to be no problem in your process.

[Ohm]

To me there seems to be no problem in your process.

well the answer is 36.

[opti384]

Well there's no problem with the equation.

And we know that if 1mol of copper oxide reacts 1mol of water is produced.

As we have 9g of water (0.5mol) there must have been 0.5 mol of copper oxide as well.

[Borek]

well the answer is 36.

No. Depending on the values used for molar masses the final result can be slightly different, it may also happen it will be differently rounded down, but I got 39.74 with EBAS - so the correct answer is close to your 40.