I keep getting errors in a simple copper sulfate experiment

[DDNow]

Homework Statement

I need to find the total number of water molecules per copper sulfate molecule. The answer is 5. But, I keep getting ~4 with the average of two dehydrating experiments.

2. Homework Equations with my Attempts

I am just using simple factor equations for these. I am converting from the weight of water that I liberated to moles. Then, comparing moles to find experimental values for the number of water molecules in the copper sulfate. I hope you understand. This is the first time I've tried to use LateX

Test 1

0.340g H₂O * $$\frac{1 mol H_{2}O}{18.016g H_{2}O}$$ = 0.0189 mol H₂O

0.6449g CuSO₄ * $$\frac{1 mol CuSO_{4}}{159.62g CuSO_{4}}$$ = 0.00404 mol CuSO₄

Experimental number of H₂O Molecules is 4.68 or $$\frac{0.0189 mol H_{2}O}{0.00404}$$

That's fine for that one, I can round up to 5 for the ratio.

For the second test, I used the same equations with the measured weight of 0.328g H₂O and 0.729g CuSO₄.

This gives 0.0182 mol H₂O and 0.00457 mol CuSO₄.

The experimental value for the number of H₂O molecules comes out to 3.98.

This is where I am not doing so well (obviously). When I average these two and round off, I get 4. To the best of my knowledge, copper sulfate tetrahydrate doesn't exist.

So, am I just dealing with imperfect lab situations (technique, materials, etc..), or is there a fundamental flaw in my approach. Thanks for your time.

Mike

 

[GCT]

It's the former.

 

[Blueshift5]

I can understand your frustration with getting inconsistent results in your experiment. It is common to encounter errors in scientific experiments, especially when dealing with complex compounds like copper sulfate. Based on the information you provided, it seems like your approach is correct and there may be some external factors causing the discrepancies in your results. It could be due to variations in the materials used, technique, or even environmental factors like temperature and humidity. To ensure the accuracy of your results, I would recommend repeating the experiment multiple times and taking careful measurements to minimize errors. It may also be helpful to consult with your instructor or a more experienced researcher for further guidance. Remember, scientific research is an iterative process and it is normal to encounter challenges and errors along the way. Keep striving for accuracy and consistency, and you will eventually find the answer you are looking for.