Increasing the volume of solution lowers experimental error?

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Discussion Overview

The discussion revolves around the relationship between the volume of HCl solutions used in a laboratory experiment and the resulting experimental error in determining the rate law for the reaction between HCl and Mg. Participants explore why a larger volume of solution might yield more accurate results compared to a smaller volume.

Discussion Character

  • Homework-related
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests that the increased volume of solution provides more surface area for reaction, potentially leading to greater results.
  • Another participant questions how relative uncertainty in volume measurements changes with larger volumes, noting that this also depends on the absolute uncertainty of the measuring device.
  • A later reply clarifies that the same measuring device was used for both 50 mL and 100 mL measurements, implying that the absolute error remains constant.
  • Further discussion highlights that while absolute error is the same, the relative error may differ between the two volumes, prompting a question about which set of measurements would have smaller relative error and the reasoning behind it.

Areas of Agreement / Disagreement

Participants express differing views on the implications of volume on experimental error, with some focusing on surface area effects and others on measurement uncertainty. The discussion remains unresolved regarding the specific reasons for the observed differences in accuracy.

Contextual Notes

Participants note that the discussion depends on the definitions of relative and absolute error, as well as the characteristics of the measuring devices used, which may not have been fully explored.

Macroer
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Homework Statement



This was part of a lab i preformed to determine rate law for HCl and Mg.


50 mL of 0.5M, 1M, 1.5M and 2M HCl solutions were made using water and this was used with Mg ribbon to find the rate law. The same 0.5M, 1M, 1.5M, 2M HCl solutions were made in 100mL solution that contained water. I was told that the 100mL solution of HCl diluted in water provided more accurate results, than the 50mL solution of HCl dilluted in water. I was wondering why this is the case?

Homework Equations


The Attempt at a Solution


Don't have that great an idea, but the increased volume of solution provides more surface area for reaction, therefore greater results?
 
Last edited:
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What happens to the relative uncertainty in your volume measurements when you use larger volumes?
(Note this also depends on the absolute uncertainty your measuring device produces. Switching from a 10 mL volumetric pipet to a 1000 mL beaker to measure volume is not advisable!)
 
PhaseShifter said:
What happens to the relative uncertainty in your volume measurements when you use larger volumes?
(Note this also depends on the absolute uncertainty your measuring device produces. Switching from a 10 mL volumetric pipet to a 1000 mL beaker to measure volume is not advisable!)

This wasn't the case as the same measuring device, with the same scale was used in both 50mL and 100mL
 
Macroer said:
This wasn't the case as the same measuring device, with the same scale was used in both 50mL and 100mL

Correct. Now if you measure 50 mL and 100 mL quantities on the same measuring device, the absolute error is the same for both sets of measurements. Which set of measurements will have the smaller relative error and why?
 

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