For each of the volumes dispensed above, do the volumes dispensed by the buret agree with the volume of liquid that ended up in the graduated cylinder? If it was not, how much was it off by?
The Correct Answer and Explanation is:
To evaluate whether the volumes dispensed by the buret agree with the volume of liquid that ended up in the graduated cylinder, we would need to perform a comparison between the two measurements: the volume dispensed (measured by the buret) and the volume recorded in the graduated cylinder. The key steps for making this assessment are:
- Recording the Volume on the Buret: Start by noting the initial reading on the buret before dispensing any liquid. After dispensing the liquid into the graduated cylinder, record the final buret reading. The volume dispensed from the buret is simply the difference between the initial and final buret readings.
- Measuring the Volume in the Graduated Cylinder: After transferring the liquid, read the volume on the graduated cylinder. This measurement represents the amount of liquid that actually ended up in the graduated cylinder.
- Comparison: Compare the volume dispensed by the buret with the volume observed in the graduated cylinder. If they match, then the buret’s measurement agrees with the cylinder’s volume. However, if they do not match, the difference between these two measurements will reveal how much the buret’s dispensing was off by.
- Possible Sources of Error:
- Parallax error: When reading the meniscus of the liquid in the buret or graduated cylinder, a misalignment in eye position can cause errors.
- Buret Calibration: The buret may not be perfectly calibrated, leading to small discrepancies between the actual and measured volumes.
- Residual Liquid: If any liquid remains in the buret tip after dispensing, the total volume delivered will be less than expected.
If a discrepancy is observed, the amount by which the volumes differ will indicate how much the buret measurement was off. For example, if the buret dispensed 25.0 mL of liquid but the graduated cylinder shows only 24.7 mL, the buret measurement is off by 0.3 mL.
Thus, if there’s any variation, identifying and understanding the error source can help reduce discrepancies in future measurements.
