Thermal Decomposition

What is the ratio of moles of CuO produced per moles of malachite decomposed?

I have 0.004522431/0.01257071 but am not that confident that I am going the right direction. Can any one tell me if I am going in the right direction or do I need to start over.

Here is where I am at so far, maybe I am off some where else.

moles of malachite in 1g: 221.12 mw
1g x 1 mole = 0.004522431
221.12 g

0.004522431 moles of malachite

moles of CuO produced: 79.55 mw
1 g x 1 mole = 0.01257071
79.55

0.01257071 moles of CuO

ratio of moles of CuO produced per moles of malachite decomposed:

0.004522431 / 0.01257071

http://en.wikipedia.org/wiki/Malachite

I would think it would be 2 CuO/mol malachite, from the aticle above. Check my thinking.

If you will multiply your ratio by 2,(the last post you did of 0.004522/0.01257) you will get 0.719 which is correct. By the way, you went about this the hard way.

malachite is Cu2CO3(OH)2 molar mass is 221.1
CuO is 79.5
There are two Cu atoms in malachite; therefore, 2CuO/CuCO3(OH)2 = 2*79.5/221.1 = 0.719

To determine the ratio of moles of CuO produced per moles of malachite decomposed, you need to use the balanced equation for the thermal decomposition of malachite.

The balanced equation for the thermal decomposition of malachite is:
2CuCO3(s) --> 2CuO(s) + CO2(g)

From the equation, it is clear that for every 2 moles of malachite (CuCO3), 2 moles of CuO are produced.

So, the ratio of moles of CuO produced per moles of malachite decomposed is 2:2, or simply 1:1.

In your calculation, it seems you have calculated the ratio as 0.004522431/0.01257071, which suggests you have the actual values for the moles instead of the molar ratio. To find the ratio, you need to use the coefficients from the balanced equation as explained above.

Therefore, you need to start over and use the balanced equation to determine the ratio correctly.