8. When 15 grams of H2O decomposes how many grams of O2 are formed?

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Discussion Overview

The discussion revolves around a chemistry problem regarding the decomposition of water (H2O) and the calculation of the mass of oxygen (O2) produced from a given mass of water. The scope includes mathematical reasoning and conceptual understanding related to chemical ratios and atomic weights.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant expresses uncertainty about how to approach the problem, indicating a lack of understanding from previous chemistry classes.
  • Another participant suggests using the atomic weights of hydrogen and oxygen to establish a ratio for the calculation.
  • A similar point is reiterated, emphasizing that the problem may involve converting units, and that ratios do not depend on units.
  • A further contribution provides a specific calculation involving the total mass of water and the mass of oxygen, suggesting that this information can lead to a straightforward calculation.
  • A participant expresses gratitude for the assistance received, indicating a potential understanding of the problem after the discussion.

Areas of Agreement / Disagreement

Participants appear to agree on the method of using atomic weights and ratios to solve the problem, but there is no consensus on the specific steps or calculations involved, as some details remain unclear.

Contextual Notes

There are limitations regarding the assumptions made about unit conversions and the specific details of the calculation process, which are not fully resolved in the discussion.

Who May Find This Useful

This discussion may be useful for students struggling with stoichiometry and the decomposition of compounds in chemistry, particularly those preparing for tests involving similar calculations.

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[SOLVED] 8. When 15 grams of H2O decomposes how many grams of O2 are formed?

Here's the question:

When 15 grams of H2O decomposes how many grams of O2 are formed?

I have no idea how to even start that problem...I guess I missed that part in Chem class. *sighs*
 
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You need to ratio the weights of the constituent parts of water. How much does a hydrogen atom weigh? How much does an oxygen atom weigh?
 
russ_watters said:
You need to ratio the weights of the constituent parts of water. How much does a hydrogen atom weigh? How much does an oxygen atom weigh?

Adding to this, the teacher will probably have the question on a test but it will be in pounds or ounces. Most people dick around with converting from grams to ounces, because they forget that ratios do not have units. Divide the units you know, which are probably grams, then apply that ratio to whatever units the question has. It could be grams, it could be pounds, it could be anything.
 
Each (1.008 + 1.008 + 16.00) mass of water contains (16.00) mass of oxygen. Now you have enough information for the ratio and the calculation for how much oxygen by mass is simple.
 
Thanks everyone...I think I've got in now. I really appreciate you help. 8)
 

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