Photo AI
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. One student put a drop of each ink onto a line on chromatography paper and se... 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 error made by the student was that the spots of ink were placed too low, below the solvent level. This would result in the ink spots dissolving directly into the solvent rather than traveling along the chromatography paper, preventing proper separation.
Step 2
Show outer electrons only.
Answer
The dot and cross diagram for a molecule of methane (CH₄) shows a central carbon atom with four hydrogen atoms attached. Representing the outer electrons:
H
•
|
H - C - H
|
•
H
The carbon atom has one shared pair of electrons with each hydrogen atom, involving a total of four pairs.
Step 3
Explain why diamond has a very high melting point.
Answer
Diamond has a very high melting point due to its strong covalent bonds and its giant molecular structure. The large number of bonds requires a significant amount of energy to break, which contributes to its high melting point. Additionally, the lattice structure means that the atoms are held tightly together, further increasing the energy required for melting.