Final answer:
To weigh out 55 mg of a substance with a balance that has a 10 mg sensitivity and 95% accuracy, you should ensure the balance is calibrated, tare it with your container, add the substance gradually, and adjust until you reach the target weight. Be aware of measurement uncertainty, as the actual mass may slightly differ from the displayed mass.
Step-by-step explanation:
Weighing out 55 mg of a substance using a prescription balance with a sensitivity requirement of 10 mg and an accuracy of 95% involves a meticulous and careful process. First, it is important to understand that the sensitivity of the balance indicates the smallest difference in mass that can be detected, while the accuracy reflects the closeness of the measured value to the true value. The balance in question can distinguish masses as small as 10 mg.
To weigh the substance:
- Ensure that the balance is calibrated and set to zero before use.
- Place a container or weighing paper on the balance to hold the substance, and use the tare function to zero the balance again if necessary.
- Carefully add the substance to the container or weighing paper, approaching the 55 mg target gradually to prevent overshooting.
- Since the sensitivity is 10 mg, add the substance in small increments that are likely below this value to incrementally reach as close to 55 mg as possible.
- Continue adjusting until the balance reading stabilizes at or near the desired weight.
- Given the 95% accuracy, there should be minimal deviation between the displayed mass and the actual mass. However, it's crucial to account for any potential error, understanding that the actual mass may slightly differ due to the accuracy limit.
Note that even with highly sensitive balances, a certain degree of measurement uncertainty always exists. In practice, a balance with these specifications would suffice for most laboratory applications, but when exactness is critical, additional calibration or more sophisticated equipment might be necessary.