Video Transcript
Fill in the blank. Gravimetric methods play an
important role in chemical analysis especially in blank. (A) Determining the amount of
analyte through qualitative analysis. (B) Determining the amount of
analyte through quantitative analysis. (C) Identifying the type of metal
precipitated through qualitative analysis. (D) Identifying the type of metal
precipitated through quantitative analysis. (E) Determining the concentration
of acid or base by qualitative analysis.
Chemists often need to identify or
quantify the composition of a material or mixture. An effective way to identify a
substance is to examine its chemical and physical properties. A known pure substance will have
unique physical properties, such as boiling point, solubility, or color. For example, at one atm, pure water
will boil at 100 degrees Celsius. So if a sample of water with
questionable purity boils at a different temperature, usually higher than 100
degrees Celsius, we can say the sample is impure. This type of analysis is known as
qualitative analysis.
Qualitative analysis is useful if
we want to determine the identity of an unknown substance, but what if we need to
determine the quantity? For example, we may need to
determine the mass, concentration, or number of moles of a substance present in a
sample or predict the amount of substance that would be made in a chemical
reaction. When we use methods to quantify a
substance, we are doing quantitative analysis.
This question is asking about a
specific quantitative technique called gravimetry or gravimetric analysis. In gravimetric analysis, we are
trying to quantify a substance based on its mass. The specific substance we are
trying to determine the mass of is known as the analyte.
Since we know that gravimetric
analysis is a quantitative method, we can eliminate answer choices (A), (C), and (E)
because these options use the term qualitative. This leaves answer choices (B) and
(D). We can eliminate answer choice (D)
because identifying is a term used when describing qualitative analysis. Answer choice (B) must be the
correct answer because it describes a quantitative analysis technique used to
determine the amount or mass of an analyte.
In conclusion, the answer choice
that completes the statement is answer choice (B). Gravimetric methods play an
important role in chemical analysis, especially in determining the amount of analyte
through quantitative analysis.
