Topic #7: Guide Questions

• What are the steps/techniques in using the

  analytical balance?

  • Prior to Weighing - Clean the balance and ensure that it is properly calibrated.
• What are the steps/techniques in using the

  analytical balance?

  • Prior to Weighing - Warm up the balance and check the leveling position by adjusting the leveling feet.
• What are the steps/techniques in using the

  analytical balance?

  • During Weighing - Ensure that the container used to hold the samples is tared first after being placed on the balance.
• What are the steps/techniques in using the

  analytical balance?

  • During Weighing - Always close the draft shields to avoid any outside residues to contaminate the sample or other environmental factors.
• What are the steps/techniques in using the

  analytical balance?

  • During Weighing - Wait for the reading to stabilize before recording the weight.
• What are the steps/techniques in using the

  analytical balance?

  • After Weighing - Be careful when removing the sample and container off the balance.
• What are the steps/techniques in using the

  analytical balance?

  • After Weighing - Wipe the weighing pan if necessary.
• What are the steps/techniques in using the

  analytical balance?

  • After Weighing - Follow any specific procedures for shutting down the analytical balance.
• What are some of the determinate and

  indeterminate sources of errors in weighing?Determinate Errors

  • Instrumental – non-ideal instrument behavior, by faulty calibrations or by use under inappropriate conditions.
• What are some of the determinate and

  indeterminate sources of errors in weighing?Determinate Errors

  • Sample Handling – contaminants or residues left on the balance pan or container.
• What are some of the determinate and

  indeterminate sources of errors in weighing?Determinate Errors

  • Personal – result from carelessness, inattention, or personal limitations of the experimenter.
• What are some of the determinate and

  indeterminate sources of errors in weighing?

  Indeterminate Errors

  • Environmental Variations – unpredictable changes in temperature or air pressure.
• What are some of the determinate and

  indeterminate sources of errors in weighing?

  Indeterminate Errors

  • Operator Handling – inconsistent handling or placement of the sample.
• What are some of the determinate and

  indeterminate sources of errors in weighing?

  Indeterminate Errors

  • Instrument Fluctuations – small, random electronic noise or balance drift.
• Why do we need to calibrate equipment such as

  analytical balance prior to doing measurement?

  • Calibrating needs to be done to ensure the measurement results are accurate and reliable. It minimizes any measurement uncertainty or errors in the readings.