To answer this problem, we write first the stoichiometric equation. Thus we have,
Cu2S + O2 => 2Cu + SO2
Next, we check if the equation is balanced or not.
(left) (right)
2 Cu = 2 Cu
1 S = 1 S
2 O = 2 O
So the stoichiometric equation is balanced, let's proceed in solving the theoretical yield of Cu given 5 g of Cu2S.
First, we solve for Cu2S in moles,
5 g Cu2S x <u>1 mol Cu2S </u> = 0.0314 mol Cu2S
159.16 g Cu2s
Secondly, convert moles of Cu2S to moles Cu. Note for every mole of Cu2S we get 2 moles of Cu. Thus,
0.0314 mo Cu2S x <u> 2 mol Cu </u> = 0.0628 mole Cu<u>
</u> 1 mol Cu2S
Lastly, we convert mole Cu to g Cu via multiplying by Cu's MW.
0.0628 mole Cu x <u>63.546 g Cu </u> = 3.99 g Cu or 4 g Cu<u>
</u> 1 mole Cu
<em>ANSWER: 4 g Cu</em>
The correct answer is
<span>3. Organic Chemistry.....</span>
Lord Kelvin, were he alive today, would be considered a Thermochemist. Thermochemistry is interested in the role of heat in chemical reactions. This includes the role of heat both as a biproduct of chemical reactions and a facilitator.
Kelvin's description of absolute zero is an important concept in thermochemistry. At absolute zero, there is no movement of molecules, and no energy available facilitate chemical reactions.
I believe the answer is C !