Can someone spot the error in the question?

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SUMMARY

The discussion centers on errors in a high school chemistry exam question regarding hydrated copper sulfate. Participants identify inaccuracies, specifically that hydrated copper sulfate is not gray and that it decomposes rather than melts when heated. Additionally, they highlight a typo in the mass calculation in part d, which misleads students. The correct interpretation involves understanding the molar ratio of water to copper sulfate, which is five moles of water per mole of CuSO4.

PREREQUISITES
  • Understanding of chemical compounds, specifically hydrated copper sulfate.
  • Knowledge of chemical decomposition and melting points.
  • Familiarity with mass percent calculations in chemistry.
  • Basic grasp of stoichiometry, particularly mole ratios.
NEXT STEPS
  • Research the properties and reactions of hydrated copper sulfate.
  • Study the process of chemical decomposition versus melting.
  • Learn how to accurately calculate mass percent in chemical equations.
  • Explore stoichiometry and mole conversions in chemical reactions.
USEFUL FOR

Chemistry students, educators preparing exam materials, and anyone involved in high school science curriculum development will benefit from this discussion.

lioric
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TL;DR
This is a question from a local exam paper.
I can see a huge error in the question
Can someone confirm this error.
IMG_20190609_191325__01.jpg
 
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Well, you made an error saying that hydrated copper sulfate was gray:
https://en.wikipedia.org/wiki/Copper(II)_sulfate
You also made an error when you said you were going to melt copper sulfate over a flame (it decomposes to sulfur trioxide and copper oxide without melting).

But yes, there seems to be an error in the mass in part d. I'm assuming that's what you were talking about.
 
TeethWhitener said:
But yes, there seems to be an error in the mass in part d. I'm assuming that's what you were talking about.

Yes. I wanted to make sure that it was a typo that the teacher made
Also look at the last answer
Technically the student is correct. Since amount of water lost was to be divided by the total mass in the beginning of the question.
It's not the student's fault that the numerator is greater than the denominator. That happened because of the typo in the question.

BTW this is the question paper of my student. I helped her study for her high school exam.
If it was me, I would have complained about the question in the exam Hall. I wouldn't have written the answer to the wrong question.
 
I’m a bit surprised that the percent in part (e) they’d be interested in is a mass percent. If you convert the masses to moles, you find that there are 5 waters per CuSO4 molar unit, which is actually the case for hydrated copper sulfate. It’s a well-written question if you get rid of the mistakes.
 
TeethWhitener said:
I’m a bit surprised that the percent in part (e) they’d be interested in is a mass percent. If you convert the masses to moles, you find that there are 5 waters per CuSO4 molar unit, which is actually the case for hydrated copper sulfate. It’s a well-written question if you get rid of the mistakes.
Of course it's well written it was copied from an olevel paper. The teacher just changed the substance and masses.
 
I came.across a headline and read some of the article, so I was curious. Scientists discover that gold is a 'reactive metal' by accidentally creating a new material in the lab https://www.earth.com/news/discovery-that-gold-is-reactive-metal-by-creating-gold-hydride-in-lab-experiment/ From SLAC - A SLAC team unexpectedly formed gold hydride in an experiment that could pave the way for studying materials under extreme conditions like those found inside certain planets and stars undergoing...

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