Mark scheme flashcards

Describe how you could obtain a pure, dry sample of the insoluble solid from the final reaction mixture. (3)

M1 filter (off the precipitate)

M2 wash (with distilled/deionised/pure water)

M3 dry in a warm oven / leave to dry / dry with filter paper

State what is meant by the term ionic bonding (2)

M1 electrostatic attraction/forces between ions

M2 of opposite charge

(metals and non-metals)

Explain why magnesium chloride has a high melting point. (3)

M1 attraction (between ions) is strong

M2 lots of ions (in structure) / giant structure / lattice / lots of/many bonds

M3 (therefore) lot of (thermal/heat) energy required to overcome attraction / to break down the lattice

Give two characteristics of a homologous series. (2)

M1 (can be represented by a) general formula

M2 each member differs from the next by a CH2 group OWTTE

M3 (each member has) same functional group

M4 (each member has) similar/same chemical properties / similar/same (chemical) reactions

M5 trend in physical properties (between successive members)

Test for cation

M1 add sodium hydroxide (solution)

M2 if blue precipitate forms solution contains copper(II) ion(s) / contains Cu2+ / is a copper compound

M3 if green precipitate forms solution contains iron(II) ion(s) / contains Fe2+ / is an iron compound

Test for anion

M4 add silver nitrate (solution)

M5 if white precipitate forms solution contains chloride ion(s) / contains Cl- / is a chloride

M6 if cream precipitate forms solution contains bromide ion(s) / contains Br- / is a bromide

Any explanation that links any three of the following points for diamond

M1 each (carbon) atom is (covalently) bonded to four other (carbon) atoms

M2 in a (giant) tetrahedral lattice /network / structure

M3 the (covalent) bonds are (very) strong

M4 (therefore) diamond is (very) hard (and so good for cutting tools)

Any explanation that links any three of the following points for graphite

M5 each (carbon) atom is (covalently) bonded to three other (carbon) atoms

M6 (the structure is) in layers

M7 weak forces (between layers)

M8 (the layers can) slide over each other/ rub off

M9 this makes graphite soft (so it can make marks on paper)

(b) When the fuel is burned, the student notices that a black solid forms on the bottom of the copper can.

(i) Identify the black solid.(1)

(ii) Explain why the black solid forms. (2)

(i) soot/carbon

(ii) M1 incomplete combustion (occurs)

M2 (because) the air/oxygen supply is limited OWTTE