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Topic: Reaction rates chem 12  (Read 1369 times)

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Offline Shay101789

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Reaction rates chem 12
« on: September 23, 2022, 11:16:34 PM »
For the reaction: 2Zn(g) + O2(g) = 2ZnO(s) If at time 0.0 seconds the weight of the whole system was 36.54g and after 60.0 seconds it was 37.23 g, what is the rate of production of ZnO in g/min?

My first thought process was to find the difference in the mass to find how much was produced:

37.23-36.54 = 0.69 g/min

… but here’s where I’m confused if that’s the reaction rate for the whole system how do I determine how much of that is from ZnO…

I feel like I’m not even going in the right direction :/

I know how to take the reaction rate of a reactant or product and convert it using a balanced equation but not sure how to apply that here. Thanks for the *delete me*!
« Last Edit: September 23, 2022, 11:33:03 PM by Shay101789 »

Offline Borek

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Re: Reaction rates chem 12
« Reply #1 on: September 24, 2022, 04:01:01 AM »
Question is poorly worded - "whole" system means all three substances, and their total mass doesn't change, that's mass conservation at work.

What it probably means is that the mass of the solid changes. You are right in your calculation of the mass increase.

No matter what exact compounds are there your solid contains two elements: Zn and O. Does the amount of Zn change?
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Offline Shay101789

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Re: Reaction rates chem 12
« Reply #2 on: September 24, 2022, 01:37:42 PM »
1:1 ratio of consumed and produced so factoring in the molar mass of Zn
There will be a change of 65.38 g / mol

0.69 g/min * 1 mol / 65.38 g = 0.01055 mol/min rxn

0.01055 mol/min * 2(82.38g) ZnO/1mol = 1.7g/min of ZnO

So the answer would be 1.7 g/min of ZnO being produced. This makes sense to me but my teacher got an answer of 3.5 g/min …

** edit - would I have to multiply it by 2 because there is 2 moles?? But I thought we already took that into account 😅

Offline Borek

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Re: Reaction rates chem 12
« Reply #3 on: September 24, 2022, 03:25:29 PM »
0.69 g/min * 1 mol / 65.38 g = 0.01055 mol/min rxn

No. What element is responsible for the mass change of the solid? What is its molar mass?
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