Final answer:
To measure 1.25 mL using a 3 mL syringe, you should draw up the plunger to the 1.2 mL mark and then further to halfway between the 1.2 and 1.3 mL markings or directly to the 1.25 mL mark, reading at the bottom of the meniscus. For tasks requiring greater accuracy, a graduated cylinder may be used.
Step-by-step explanation:
To measure 1.25 mL using a 3 mL syringe, you would first ensure that the syringe is clean, accurate, and properly calibrated. Syringes often have markings at various intervals to help with precise measurements. Although it is more common to have graduations for every 0.1 mL, some syringes may also have smaller increment markings.
If the syringe has markings at every 0.1 mL, you would draw up the plunger until the liquid level is at the 1.2 mL marking. Then, carefully draw up more liquid to reach halfway between the 1.2 mL and 1.3 mL markings. If the syringe has smaller increment markings, simply align the plunger to the 1.25 mL mark directly. It is important to make a reading at the bottom of the meniscus—the curve seen at the top of the liquid. The surface tension causes the liquid to form this meniscus, and the correct volume is determined from the point at which the meniscus's bottom touches the syringe marking.
Some measurements require the use of a graduated cylinder for greater accuracy. For example, in a quality control scenario, the chemist would use the most appropriate measuring tool to ensure precision. The context provided in the question does not indicate a need for such precision, but if you were measuring for a critical application, a syringe might not be precise enough, and you would use a graduated cylinder instead.