PCAT Chemical Processes – Mercury Meniscus
- Dec 18, 2017
- PCAT Question of the Day
Mercury is a liquid with greater cohesive than adhesive forces, when placed in a glass tube (such as in a barometer). The meniscus formed with such a liquid would appear:
Click for Explanation
The classic concave meniscus that we see with water in a graduated cylinder is because the water has greater adhesive forces between the water and the glass than cohesive forces (the water sticking to itself). Since the water “wants” to stick to the walls of the container, it crawls up the sides of the container a bit to get more surface area sticking to the cylinder. Those higher edges create that classic concave meniscus.
The situation described in the question is the reverse of that – stronger cohesive forces. So the meniscus we see would be the opposite: convex instead of concave. Thus, the answer is (A) Convex.
Search the Blog
Free ConsultationSchedule Now
Free MCAT Practice AccountNeed great MCAT practice?
Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.Learn More