[ch3mgirl]

I'm not sure how to go about answering a few questions. Could someone walk me through how to solve the following?

The chemical equation is: 2ZnS + 3O₂  2ZnO + 2SO₂

1. How many molecules of sulfur dioxide could be produced from 0.485g of Zns?
(Would I go about converting the g to moles to molecules first?)

2. If the reaction of 0.485g of ZnS produced 0.288g of ZnO, what was the yield of the reaction in percentage terms?

Any help is greatly appreciated... thank you!

[DevaDevil]

1. How many molecules of sulfur dioxide could be produced from 0.485g of Zns?
(Would I go about converting the g to moles to molecules first?)

yes you would: grams -> moles, then determine how many moles of SO₂ were made, then convert to molecules.


2.
what is the definition of %yield?

[ch3mgirl]

1. How many molecules of sulfur dioxide could be produced from 0.485g of Zns?
(Would I go about converting the g to moles to molecules first?)

yes you would: grams -> moles, then determine how many moles of SO₂ were made, then convert to molecules.


2.
what is the definition of %yield?

Okay, so could someone check me on this first one?

The chemical equation is: 2ZnS + 3O2    2ZnO + 2SO2

moles of ZnS = 0.485g (1 mol/97.456g) = 0.00498 mol
the ration between Zns and SO₂ is 2:2 (or 1:1)
moles of SO₂ = 0.00498
so,
0.00498 mol SO₂ (6.022x10²³ molecules/1 mol SO₂) = 3.00 x 10²³ molecules

Is this correct?

[DevaDevil]

yes it is

[ch3mgirl]

Thanks so much!

Okay, now for the second part... let me know if I completely butchered this...

moles of ZnS = 0.485g(1 mol/97.456g)= 0.00498
moles of ZnO = 0.288g (1 mol/81.408g)= 0.00354 mol

Theoretical Tield ZnO: 2 moles ZnO/2 moles ZnS x (0.00498 mol Zns) = 0.00498 mol ZnO
% yield: 0.00354/0.00498 x (100%) = 71.1%

is this correct?

[rabolisk]

Correct.

[ch3mgirl]

Excellent, thanks so much for all your feedback and *delete me* 

[sjb]

0.00498 mol SO₂ (6.022x10²³ molecules/1 mol SO₂) = 3.00 x 10²³ molecules

Is this correct?

You seem to be wrong in terms of magnitude here - 5 x 10^-3 x 6 x 10²³ != 3 x 10²³.