Video Transcript
What apparatus is shown in the
illustration? (A) A gas syringe apparatus for
measuring the volume of the gas produced. (B) A titration experiment for
measuring the concentration of the hydrochloric acid. (C) A graduated cylinder for
measuring the volume of the liquid in the beaker. (D) A graduated cylinder for
measuring the volume of the gas in the rubber tubing. Or (E) a water displacement
apparatus for measuring the volume of the gas produced.
Let’s have a look at the devices
described in our answer choices to compare them to the apparatus given in the
illustration. Gas syringes, as the name suggests,
are used to measure the volume of gases. A gas syringe can be connected
using rubber tubing to an Erlenmeyer flask where gas is being produced, likely from
a reaction. As the gas is produced and enters
the syringe, it will push the plunger back and the volume of the gas collected can
then be read from the gradations on the syringe. We can see that a gas syringe is
not present in the illustration, so we can eliminate answer choice (A).
In a titration experiment,
generally, a buret is clamped upright using a stand over a vessel, such as an
Erlenmeyer flask. Burets are extremely precise pieces
of glassware with many gradations along their long, thin cylindrical shape and a
stopcock to control the flow of liquid out of the buret. We can see that the illustration
given does not match the setup of a titration experiment. We can eliminate answer choice
(B).
Both answer choices (C) and (D)
mention a graduated cylinder, which can also be called a measuring cylinder. Graduated cylinders are used very
commonly in chemistry as they can be used to measure the volume of substances using
the gradations along their long, cylindrical shape. Graduated cylinders come in many
different sizes, and the most common use is to measure the volume of a liquid. However, we can see from the
illustration that the liquid in the beaker is not being poured into the graduated
cylinder to measure its volume, so we can eliminate answer choice (C).
Another way a graduated cylinder
can be used is by filling it with water and inverting it into another vessel with
water, such as a beaker. Now filled with water, this setup
can utilize the gradations of the graduated cylinder to measure the volume of
another substance. For example, if a gas is being
produced and its volume needs to be measured, water displacement in the graduated
cylinder can be used. The vessel in which the gas is
being produced can be sealed off with the exception of some type of tubing that can
be placed under the opening of the graduated cylinder.
As the gas is produced and flows
through the tubing, it can bubble up through the water in the cylinder and displace
the water back down into the water bath, as long as the opening of the cylinder is
kept below the surface of the water. Then, the volume of the gas
produced can be read from the gradations of the cylinder. This setup is called a water
displacement apparatus, and we can see that it does match the illustration
shown. And it is being used to measure the
volume of hydrogen gas produced from the reaction between the zinc plate and the
hydrochloric acid.
Additionally, the graduated
cylinder in this apparatus is not being used simply to measure the gas in the rubber
tubing. The gas produced in the reaction
moves through the tubing to reach the graduated cylinder. So we can eliminate answer choice
(D). Therefore, the apparatus that is
shown in the illustration is answer choice (E): a water displacement apparatus for
measuring the volume of the gas produced.
