18:25 ll 15
You are given an unknown Substance and
told that it could be one of the three substances.
L. Mor N. You developed the two sets of
chromatograms below. From the chromatograms,
deduce the identity of X
台
solvent -
front
starting -
line
XLMN
developed
with water
XL M N
developed
with ethanol
A It could be either Lor M.
B It could be either Mor N.
C It must be La
DIt must be N.
Problem-solving strategy:
If two substances are identical, they will
have the same height on a chromatogram
regardless of the solvent used.
3. Dyes that are allowed in loods are given E
numbers. Four such E numbers commonly
used in soups are E120, E122, E124 and E162.
The chromatogram below was obtained from
three tomato soups X, Y and Z. Soup 2 was a
new soup on the market. A chemist was testing
it to ensure that all of the dyes used in making
the soup were legal.
Х
Y
Z
E120 122 E124 E162
a) Explain wity water can be used as a solvent.
b) Why was the pencil line, on which the spots
were placed, drawn above the level of the
solvent?
c) Which soup contains all lour E numbers?
d) Are the E numbers in soup 2 legp? Explain
your awer.
IM​

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).

level 4 to level 2 : ))