Why the experimental error for CaOH is larger than MgO?

In summary, the conversation is about a lab on the experimental application of Hess's law. Two experiments were conducted using different substances and the standard heat of formation was calculated. A question was raised about the large experimental error for the calcium hydroxide and the impact of assuming it was in solid form. The person is unsure about what calculation to do or how to explain the discrepancy and is seeking help. However, there seems to be some confusion in the original post about the substances used and the error being mentioned twice.
  • #1
Alpha123
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Homework Statement



I did a lab on the experimental application of Hess's law. There were two experiments where a substance in a solution was dissolved and the temperatures were recorded. Then the standard heat of formation for the substance was calculated. The first experiment used MgO and HCL and the second experiment used CaOH and water.

A question in the lab was :

"Explain why the experimental error for the calcium error for the calcium hydroxide is much larger than magnesium oxide.In this experiment, it was assumed that the calcium hydroxide formed was in the solid form, whereas some of the solid that formed must have dissolved. Using this information, determine by calculation how much of an impact the above assumption had on the final experimental value for the heat of formation of calcium hydroxide."

I don't quite understand what calculation to do here, or an explanation for this either. It cannot be the percentage error as i have already calculated those in an earlier question. Any help on this question would be very much appreciated, thank you.
 
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  • #2
Can you account for the discrepancy with an assumption of partial hydrolysis?
 
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Likes Alpha123
  • #3
I don't know what that means, we haven't learned it in class.
 
  • #4
Sounds cryptic to me.

But to be honest - your post starts with CaOH instead of Ca(OH)2 and contains statements like

Alpha123 said:
the experimental error for the calcium error for the calcium hydroxide

so I am not convinced the problem is correctly represented.
 

1. Why is the experimental error for CaOH larger than MgO?

The experimental error for a substance depends on various factors such as the precision of the measuring instruments, the technique used in the experiment, and the inherent properties of the substance. In the case of CaOH and MgO, CaOH is a more reactive compound and is prone to absorb moisture from the air, leading to a higher experimental error.

2. Can the experimental error for CaOH and MgO be reduced?

The experimental error can be reduced by using more accurate measuring instruments and techniques, such as using a balance with a higher precision or performing multiple trials to calculate an average value. Additionally, taking proper precautions to prevent moisture absorption can also help reduce the experimental error.

3. Does the experimental error for CaOH and MgO affect the accuracy of the results?

Yes, a larger experimental error can affect the accuracy of the results. However, it is important to note that the experimental error is a measure of the precision of the results and does not necessarily reflect the accuracy. It is always advisable to perform multiple trials and calculate an average to minimize the impact of experimental error on the accuracy of the results.

4. Are there any other factors that can contribute to a larger experimental error for CaOH than MgO?

Yes, apart from the inherent properties of the substances, there are other factors that can contribute to a larger experimental error for CaOH than MgO. These include human error, environmental conditions, and the purity of the substances used in the experiment.

5. How can we minimize the impact of experimental error on the results for CaOH and MgO?

To minimize the impact of experimental error, it is important to follow proper experimental techniques, use accurate measuring instruments, and perform multiple trials. Additionally, taking precautions to prevent any external factors that can contribute to a larger experimental error, such as moisture absorption, can also help in obtaining more accurate results.

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