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Some students were asked to separate and identify the dyes in four inks, W, X, Y and Z - Edexcel - GCSE Chemistry - Question 3 - 2018 - Paper 1
Question 3
Some students were asked to separate and identify the dyes in four inks, W, X, Y and Z. A student put a drop of each ink onto a line on chromatography paper and set ... show full transcript
Worked Solution & Example Answer:Some students were asked to separate and identify the dyes in four inks, W, X, Y and Z - Edexcel - GCSE Chemistry - Question 3 - 2018 - Paper 1
Step 1
Explain the error made by the student when the apparatus was set up.
Answer
The student made the error of placing the ink spots below the solvent level. As a result, the inks would dissolve into the solvent, which would not enable proper chromatography. The inks should be placed on the line above the solvent level to allow for effective separation.
Step 2
Show outer electrons only.
Answer
The dot and cross diagram for the methane molecule, CH₄, is as follows:
H
|
H - C - H
|
H
In this diagram, the hydrogen atoms (H) have one dot each representing their single outer electron, while the carbon atom (C) shares its four valence electrons through bonds with the hydrogen atoms.
Step 3
Explain why diamond has a very high melting point.
Answer
Diamond has a very high melting point because of its strong covalent bonds forming a giant lattice structure. This structure results in a large number of bonds that need substantial energy to break. Consequently, diamond requires a significant amount of heat to reach the temperature needed for these bonds to break.