Magnesium oxide smoke lost during the reaction?

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Discussion Overview

The discussion revolves around the impact of potential loss of magnesium oxide (MgO) smoke during the reaction of magnesium with oxygen gas on the Mg:O ratio. Participants explore the implications of mass loss on empirical formula calculations, including experimental setups and assumptions made during measurements.

Discussion Character

  • Homework-related
  • Exploratory
  • Technical explanation

Main Points Raised

  • One participant questions whether the Mg:O ratio would change if some magnesium oxide smoke escaped during the reaction, suggesting that the ratio might remain unchanged.
  • Another participant proposes a thought experiment where the loss of ash mass is considered, prompting a reevaluation of the ratio calculation.
  • A participant who has conducted a similar experiment speculates that if ash mass is lost, the numbers for calculating the ratio would be smaller, yet suggests that the ratio might still remain unchanged due to the reduction of MgO.
  • Several participants emphasize that the balance used for weighing does not inherently recognize the substance being measured, and that the interpretation of mass is assigned by the user.
  • One participant points out two assumptions made during calculations: that the product is pure MgO and that all magnesium was converted to oxide without loss.
  • A suggestion is made to subtract a percentage from the mass found and repeat the calculations to see if the ratio remains identical to previous results.

Areas of Agreement / Disagreement

Participants express differing views on whether the Mg:O ratio would remain unchanged with mass loss. Some believe it may change, while others argue it could stay the same, indicating a lack of consensus on this point.

Contextual Notes

Participants highlight assumptions regarding the purity of the product and the completeness of the reaction, which may affect the calculations but remain unresolved in the discussion.

Cuisine123
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Homework Statement


Would the Mg : O ratio be affected if some magnesium oxide smoke escaped during the reaction of Mg with oxygen gas?

Please explain with a sample calculation. Thanks.

Homework Equations


I know that the empirical formula is MgO.

The Attempt at a Solution


I don't understand how to do this question., but I think that the ratio will remain unchanged?
 
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I assume you are calculating the ratio by weighing the magnesium ribbon before combustion and then weighing the ash after combustion. If some ash mass is lost, what will this do to your calculation?

You need to set up a thought experiment and then remove a little of the mass of ash and recalculate. What happens to the ratio?
 
chemisttree said:
I assume you are calculating the ratio by weighing the magnesium ribbon before combustion and then weighing the ash after combustion. If some ash mass is lost, what will this do to your calculation?

You need to set up a thought experiment and then remove a little of the mass of ash and recalculate. What happens to the ratio?

I have already done an experiment to find out the empirical formula for Magnesium Oxide, but this is a follow-up question..If some ash mass is lost, then I guess the numbers to calculate the ratio would be smaller?
But since MgO is already reduced, then I guess the ratio will remain unchanged?

Also, how can I show it with a sample calculation? Thanks.
 
When you weighed the MgO, the balance didn't know it was MgO. All the balance tells you is how much mass is in the pan. YOU assign meaning to the reading.
 
chemisttree said:
When you weighed the MgO, the balance didn't know it was MgO. All the balance tells you is how much mass is in the pan. YOU assign meaning to the reading.

Sorry, I still don't understand.
 
When doing calculations for th eesxperiment, you are making two assumptions - even if you are not aware of the fact that you are doing them.

First, you assume that the product that you have weighted is pure MgO.

Second, you assume that all Mg was converted to the oxide and none was lost.

Do you see now?

As for the calculations:

If there were some MgO lost in the form of "smoke", final mass of the product will be smaller. Subtract 10% from the mass you have found and repeat the calculations identical to those you have already performed. What ratio did you get this time? Is it identical to the one you got previous time?
 

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