chem lab (analysis1)

Question 1

what is chemical analysis

Answer 1

the determination of the
-identity of the chemical substance(qualitative)
-amount of a particular substance (quantitative)

Question 2

2 types of chemical analysis and their definition

Answer 2

1. clinical analysis/non-instrumental analysis is a group of analytical methods the only requires chemicals, balance, calibrated glassware, and other common laboratory apparatus. An instance is the TITRATION.
2. instrumental analysis uses an analytical instrument in chemical analysis to determine the identity or amount of the analyte. An instance is BEER’S LAW

Question 3

what is an analytical instruments?

Answer 3

devices that measure a
physical or chemical property of the analyte

Question 4

3 major categories of instrumental analysis

Answer 4

• Spectroscopic methods (Spectroscopy)
• Electroanalytical methods
• Separative methods

Question 5

what is electromagnetic spectrum?

Answer 5

term used by scientist to describe the entire
range of light in the universe. The spectrum ranges from radio waves to gamma
rays.

Question 6

in what ways can light be described?

Answer 6

in terms of frequency, hertz (Hz) and wavelength

Question 7

hertz

Answer 7

measures the frequency or the number of waves that pass by a point in
one second

Question 8

wavelength

Answer 8

measures the distance from the peak if one wave to the peak of
the next

Question 9

what does it means when the hertz and wavelength become inversely related to each other?

Answer 9

the larger the
frequency, the smaller the wavelength

Question 10

spectroscopy

Answer 10

-study of the interaction of energy with radiated
matter
-an area of science that is concerned with absorption, emission, and
scattering of electromagnetic radiation by atoms and molecules.
(Hanson, et. al., n.d.)

Question 11

spectrometry

Answer 11

the measurement of the interactions between light
and matter. Also includes the reactions and measurements of radiation
intensity and wavelength.

Question 12

spectrophotometry

Answer 12

method used to measure how much a chemical
substance absorbs light by measuring the intensity of light, when a
beam of light passes through the sample solution

Question 13

what is the basic principle of spectrophotometry

Answer 13

each
compound absorbs, transmits, or reflects light (light as in
electromagnetic radiation) over a certain wavelength. The
absorb light or transmitted light is then measured which is
unique for every chemical substance.

Question 14

spectrophotometer

Answer 14

the instrument used to measure
the intensity of light absorbed after it passes through the
sample solution.

Question 15

colorimetry

Answer 15

-one of the earliest spectroscopic

Question 16

in year 1856, early colorimetric analysis is the Nessler’s method for?

Answer 16

ammonia

Question 17

what does nessler’s method uses and involve

Answer 17

• Nessler’s method uses visual comparison between
  the colour produced by an unknown amount of a
  substance in sample solution with the same colour
  produced by a known amount of the same substance
  in standard solutions.
• Nessler’s method involves preparation of standard
  solutions with varying concentrations.
• the colour of the sample solution that approximately
  matches the colour of one of the prepared standards is
  the concentration of the unknown solution.

Question 18

Modern day colorimetric methods no longer use Nessler’s
tube but colorimeters. TRUE OF FALSE?

Answer 18

true

Question 19

colorimeters

Answer 19

-used to determine the concentration of
substances that absorb light in the visible region (wavelength
= 400 – 800 nm).
-light-sensitive device measuring the transmittance and
absorbance of light passing through a liquid sample.
-only applicable to colored solutions.
-Designed to perform a psychophysical sample analysis or
measurements correlate to the human perception.

Question 20

the principle of colorimeter is based on?

Answer 20

Beer – Lambert’s
Law

Question 21

The Beer-lambert law states that

Answer 21

“there is a linear
relationship between the concertation and the
absorbance of the solution, which enables the
concentration of a solution to be calculated by
measuring its absorbance”.

Question 22

The absorbance depends on two external assumptions: namely?

Answer 22

• The absorbance is directly proportional to the
  concentration (c) of the solution of the sample used
  in the experiment.
• The absorbance is directly proportional to the length
  of the light path (l) which is equal to the width of the
  cuvette.