Q4 Exam Questions Flashcards
(32 cards)
Define (i) atomic number, (ii) mass number
Atomic number = number of protons in the nucleus of an atom.
Mass number = number of protons and neutrons in the nucleus of an atom.
Taking the valency of gallium (Ga) as 3, write the formula for the simplest compound formed from (i) gallium and nitrogen, (ii) gallium and oxygen.
Gallium and nitrogen = GaN
Gallium and oxygen = Ga2O3
Predict the two possible shapes of a molecule AB, where n = 2
V-shape
Identify the energy change associated with the following balanced equation: X+ (g) —> X2+ (g) + e-
Second ionisation energy
What is diffusion?
The spreading of molecules from an area of high concentration to low concentration.
Stage 2 and 4 of mass spectrometry
2 = ionisation
4 = separation
A laboratory technician diluted 25.0 cm^3 of a 0.12 M solution to 30.0 cm^3 by adding deionised water. Find the new concentration of the solution in moles per litre.
25x0.12/30 = 0.1M
What is an enzyme?
A biological catalyst that alters the rate of a reaction.
Draw a structure of propane-1,2,3-triol (glycerol) to show al of its atoms and al of its bonds.
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H-C-C-C-H
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OH OH OH
The set of elements {Li, Na, K} is one of Dobereiner’s triads. Refer to this example to explain Dobereiner’s contribution to the development of the periodic table.
Li, Na, and K groups all have similar chemical properties.
The atomic mass of Na is the average of Li and K.
Why is a photon emitted as the electron moves from one energy level to another as shown?
The electron in the outer shell has more energy/in an excited state.
Why is the second ionisation energy of lithium significantly larger than its first?
The second electron comes from the shell that is closer to the nucleus.
What colour is observed in a flame test on a salt of (i)lithium, (ii) copper?
Lithium = red
Copper = blue/green
State Avogadro’s Law
Equal volumes of all gases, at the same temperature and pressure, have the same number of molecules.
One of the largest diamonds ever mined was found in Botswana in June 2021. The diamond had a mass of 1098 carats and contained exactly 18.3 moles of carbon. Assuming this stone contained only carbon, calculate the mass of one carat expressed in grams.
18.3x12(carbon) = 219.6g of Carbon in 1098 carats
One carat = 219.6/1098 = 0.200g
What reagents are used to confirm the presence of nitrate ions in an aqueous solution?
Iron (III) sulfate
Which one ofthe following four compounds would you expect to have the strongest carbon to carbon bonding: ethane, ethene, ethyne, benzene?
Ethyne
The structure of aspirin is shown. Calculate the average daily dose (in mg) when a person took a total of 0.146 moles of ‘low dose’ aspirin over 365 days.
Aspirin = C9H8O4, Mr = 180
0.146x180 = 26.280g aspirin in 365 days
26.28/365 = 0.0720g per day
0.0720x1000 = 72.0mg per day
Draw a labelled diagram of Thompsons plum pudding model of the atom
The diagram represents the 10 electrons in the 4s and 3d sub-levels of a neutral atom of a certain element in its ground state. What is the element?
Nickel
What isotope is produced when the nucleus of an 241/95Am atom releases an alpha particle?
Neptunium237
Write the chemical formulae for: (i) magnesium sulfite, (ii) copper(ll) oxide.
Magnesium sulfite = MgSO3
Copper (III) oxide = CuO
Give two possible shapes of a covalent molecule with the general formula QX3
Trigonal
Each of the small metal canisters shown in the photograph contains 0.36 moles of carbon dioxide. The contents of one canister were released into a flat bicycle tube.
The gas inflated the tube to a volume of 1.0x 103 m3ata temperature of 293 K. Calculate the pressure of the gas inside the tube correct to two significant figures.
