CHEM EXAM Flashcards
(22 cards)
Deduce the number of protons and electrons in an Fe3+ ion. atoic number is 26
proton is 26 electron is 23
The elements in Group VII of the Periodic Table are known as the halogens. Halogens can form
halide ions.
(a) Identify the halogen with the lowest density at r.t.p. (room temperature and pressure).
fluorine
State what is meant by the term covalent bond.
electron(s) shared between two atoms
Name one halide ion which bromine molecules can displace. and why
iodide, bromine is more reactive than iodide
Name a halide compound which can be used to detect the presence of water.
cobalt(II) chloride
Define the term base.
proton acceptor
State what is meant by the term alkali.
a soluble base
Thymolphthalein is an indicator.
State the colour of thymolphthalein in:
● NaOH(aq)
● CH3COOH(aq)
blue
colourless
Name an indicator which can be used to identify the substance with the highest
concentration of H+
(aq) ions
universal indicator
Write the ionic equation which represents a neutralisation reaction between any acid and any
alkali.
H+ + OH– → H2O
State two characteristics of an equilibrium
the rate of forward reaction equals (the rate of the) reverse reaction
concentrations of reactants and products are constant
State what is meant by the term closed system
nothing can enter or leave
Which test is used to show that a sample of water is pure
(a) Evaporate the water to see if any solids remain
(b) heat the water to check its boiling point
(c) Test with anhydrous cobalt (II) chloride
(d) use the universal indicator to check its PH
Heat the water to check its boiling point
Chromatography is used to separate and identify the components in both coloured and colourless mixtures. for colourless mixtures the chromatograam has to be treated with another chemical what is the name of this type of chemical
locating agent
Lithium reacts with fluorine to form the compound lithium fluoride which statement about this reaction is correct
(a) Each fluorine atom gains one electron
(b) Each fluorine atom gains two electrons
(c) Each fluorine atom loses one electron
(d) Each fluorine atom loses two or more electrons
each fluorine atom gains one electron
Solid X has a high boiling point. its structure has positive ions surrounded by a sea of electrons.
which other properties does solid X have.
(a) brittle and an electrical conductor
(b) brittle and an insulator
(c) malleable and an electrical conductor
(d) malleable and an insulator
malleable and an electrical conductor
The equation for the decomposition of magnesium nitrate is shown. 2Mg(NO3)2–> 2MgO+4NO2+O2 which volume of gas is produced when 0.1 moles of magnesium nitrate is decomposed completely
6
Which statement about the elctrolysis of molten lead(II) bromide are correct
1 Lead ions mmove to the anode and are oxidised
2 Lead ions move to the cathode and are reduced
3 Bromide ions move to the anode and are oxidised
4 Bromide ions move to the cathode and are reduced
2 and 3
Aqueous copper(II) sulfate is electrolysed using carbon electrodes. which statement is correct
A. Bubbles of hydrogen are formed at the anode
B. bubbles of oxygen gas are formed at the cathode
C. copper is deposited at the anode
D. The blue colour of the solution fades
The blue color of the solution fades
Which statements about hydrogen fuel cells are correct
1. The reaction between hydrogen and oxygen is endothermic
2. The waste product in a hydrogen fuel cell is water
3. A chemical reaction in the cell produces hydrogen which is used as a fuel
4. A hydrogen fuel cell is used to generate electricity
2 and 4
What is metallic bonding
The attraction between a lattice of positive ions and delocalized electrons
state the meaning of the term diatomic
Molecule consists of two of the same atom covalently bonded
