Chemistry - General Information

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a) A continuous emission spectrum contains a spread of all the colours from red through to violet. A line spectrum has only distinct coloured lines against a black background. b) Sketch the four lines, be sure to have them converging towards the high frequency end of the spectrum. See Figure 6 in section "2.2.1 Emission spectra". You could label the colours red, blue, indigo, violet. Make sure you indicate the direction in which frequency, or wavelength, is increasing. c) The presence of discrete lines in an emission spectrum means that there are only particular energy levels where electrons can exist, otherwise the spectrum would be a smear of light. A line represents an electron falling from a higher to a lower energy level giving out a photon of light.

(a) Evidence showing the existence of energy levels in atoms is provided by line spectra. State how a line spectrum differs from a continuous spectrum. (1) (b) Sketch the visible line spectrum of hydrogen showing its four major lines. (2) (c) Explain how the formation of lines indicates the presence of energy levels. (2)

(a) 1s2 2s2 2p6 3s2 3p6 (b) possible positive ions: K+ / Ca2+ / Sc3+ /Ti4+ possible negative ions: Cl- / S2- / P3-

(a) State the full electron configuration for argon. (1) (b) Give the formulas of two oppositely charged ions which have the same electron configuration as argon.

a) Draw a dumbbell-shaped orbital along the z-axis; make sure that you label the axes. b) 1s2 2s2 2p6 3s2 3p6 3d5 / five unpaired electrons c) look online

(a) Using the framework of the x, y and z coordinates, draw the shape of the pz atomic orbital. (1) (b) State the electron configuration of Fe3+ ion. How many unpaired electrons are there in this ion? (2) (c) The element selenium (Z = 34) has electrons in the 4s, 3d and 4p orbitals. Draw an electron in box diagram to represent these electrons. (1)

D. 48

1 mol of any gas occupies 24 dm3 at room temperature and pressure. When 32 g of methane burn completely in oxygen at room temperature and pressure what volume of carbon dioxide, in dm3, will be formed? A. 16 B. 24 C. 32 D. 48

melting point trend

1. decreases down group 1 2. increase down 17 3. increase across a period and reach a maximum at group 14

C. 64

32 g of a metal, M, reacts with 8 g of oxygen to form an oxide. The formula of the oxide is MO. What is the atomic mass of M in g mol-1? A. 16 B. 32 C. 64 D. 128

B. I and III only

98 g of a pure hydrocarbon contains 84 g of carbon. Which statements are correct? I. The compound has an empirical formula of CH2. II. The compound has a molecular formula of C7H14. III. Not enough information has been given to deduce the molecular formula. A. I and II only B. I and III only C. II and III only D. I, II and III

hydroxyl group

A functional group consisting of a hydrogen atom joined to an oxygen atom by a polar covalent bond. Molecules possessing this group are soluble in water and are called alcohols.

carboxyl group

A functional group present in organic acids and consisting of a single carbon atom double-bonded to an oxygen atom and also bonded to a hydroxyl group (COOH or Carboxylic Acid)

homogeneous mixture

A mixture in which all of the substances are present in the same state and are speed equally through the mixture

heterogeneous mixture

A mixture in which the substances are present in different states and are not spread equally through the mixture

Saturated molecule

A molecule that only has single carbon-carbon bonds.

Unsaturated molecule

A molecule with one or more carbon-carbon double bonds.

A. The concentration of the acid decreases during the reaction.

A reaction between an acid and a metal carbonate takes 60 seconds before it is completed. Why is the initial rate of the reaction faster than the rate after 50 seconds? A. The concentration of the acid decreases during the reaction. B. The temperature of the reaction decreases as it proceeds. C. The particle size of the metal carbonate decreases as the reaction proceeds. D. The carbon dioxide produced dissolves in the water as the reaction proceeds.

Addition reaction

A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule

Substitution reaction

A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms.

A solid has a high melting point, does not conduct electricity as a solid, but does when it is dissolved in water. What type of substance is the solid? a) A metallic lattice b) A giant molecular, or network, solid c) A simple molecular substance d) An ionic solid

equilibrium

A state in which forward and reverse reactions are occurring at the same rate in a closed system.

C. Measuring the change in colour of the contents of the flask over time.

A student wished to follow the rate of the reaction between calcium carbonate and hydrochloric acid. Which of the following methods would not work? A. Measuring the volume of carbon dioxide gas evolved over time. B. Measuring the change in mass of the contents of the flask over time. C. Measuring the change in colour of the contents of the flask over time. D. Measuring the change in pH of the contents of the flask over time.

mole

A unit of amount equal to the number of atoms in exactly 12g of carbon-12

Amphiprotic

Able to act as a Bronsted-Lowry acid and Bronsted-Lowry base

A. lone pair-lone pair > lone pair-bond pair > bond pair-bond pair.

According to VSEPR theory, repulsion between electron pairs in a valence shell decreases in the order A. lone pair-lone pair > lone pair-bond pair > bond pair-bond pair. B. bond pair-bond pair > lone pair-bond pair > lone pair-lone pair. C. lone pair-lone pair > bond pair-bond pair > bond pair-lone pair. D. bond pair-bond pair > lone pair-lone pair > lone pair-bond pair.

H3PO4

Alkenes undergo addition reaction. Which molecule catalyst is often used from the change from Alkenes to Alcohols?

Nickel, Palladium, Platinum

Alkenes undergo addition reactions. Which metal catalyst is often used in the hydrogenation reactions that converts them into alkanes? State the name of the catalyst only.

secondary alcohol

An alcohol in which the -OH group is attached to a carbon atom that is attached to two carbon chains and one hydrogen atom.

tertiary alcohol

An alcohol in which the hydroxyl (-OH) group is attached to a carbon that is in turn attached to three other carbons.

alkyl group

An alkane with a hydrogen atom removed

c) Electrons and protons

An atom of any element contains equal numbers of which of the following sub-atomic particles: a) Electrons, neutrons and protons b) Electrons and neutrons c) Electrons and protons d) Neutrons and protons

Pauli Exclusion Principle

An atomic orbital may describe at most two electrons, each with opposite spin direction

d) It is found in period 2 in the p-block of the periodic table.

An element has the electron configuration 1s2 2s2 2p5. Which of the following is correct about this element? a) It is found in period 1 in the p-block of the periodic table. b) It is found in period 2 in the s-block of the periodic table. c) It is found in period 2 in the d-block of the periodic table. d) It is found in period 2 in the p-block of the periodic table.

calorimeter

An instrument that measures the heat changes that occur during a reaction

b) Cu+

An ion has the electron configuration 1s2 2s2 2p6 3s2 3p6 3d10. Which of the following ions could it be? a) Ni2+ b) Cu+ c) Cu2+ d) Co3+

isotopes

Atoms of the same element that have different numbers of neutrons and different mass number

isotope

Atoms of the same element with different mass numbers as they contain different numbers of neutrons in their nucleus.

d) It has a smaller atomic radius than strontium (WHY: the atomic radius of barium is larger than that of strontium as it has an additional occupied main energy level which gives it a larger atomic radius, not smaller.)

Barium is an element in group 2 of the periodic table. Identify which of the following statements about barium is incorrect. a) It has six occupied main energy levels b) It has a lower first ionisation energy than magnesium c) It has two electrons in its valence shell d) It has a smaller atomic radius than strontium

Ethers

C-O-C

D. It enables the position of equilibrium to be reached faster.

Catalysts provide an alternative pathway for a chemical reaction. What is true about this alternative pathway? A. It provides a lower enthalpy change for the reaction. B. It provides a higher activation energy for the reaction. C. It lowers the temperature of the reaction. D. It enables the position of equilibrium to be reached faster.

Hydrogen Emission Spectrum

Color lines indicate the wavelengths of light that are released

Oxygen, O2 - Double bond (Bond order is 2) Stronger bond costs more energy to break, provided by shorter wavelength UV radiation. Ozone, O3 - One-and-a-half bond (Bond order is 1.5) Weaker bond costs less energy to break, provided by longer wavelength UV radiation. In the atmosphere, high-energy UV breaks the strong bonds in O2 so that O3 can be formed. Lower-energy UV breaks the weaker bonds in O3. This cycle is crucial for life on earth as it absorbs two types of UV radiation and maintains O3 levels in the atmosphere.

Compare the bond strength in ozone with the bond strength in oxygen and describe its importance for the atmosphere.

A. +185

Consider the following three bond enthalpies (in kJ mol-1) H—H -> 436 Cl—Cl -> 243 H—Cl -> 432 What is the enthalpy change (in kJ) for the reaction below? 2HCl(g) → H2(g) + Cl2(g) A. +185 B. +237 C. -185 D. -237

c) K (WHY: Ionisation energies decrease down a group and generally increase across a period. Of these elements, K has the largest atomic radius and the lowest first ionisation energy value.)

Deduce which of the following elements has the lowest first ionisation energy value. a) C b) Mg c) K d) He

a) First ionisation energy and electronegativity (WHY: First ionisation energy and electronegativity increase across a period with increasing nuclear charge and decreasing atomic radius.)

Deduce which of the following increases across a period (from left to right) in the periodic table. a) First ionisation energy and electronegativity b) Electronegativity and ionic radius c) Atomic number and atomic radius d) First ionisation energy and atomic radius

c) Mg2+ (WHY: On first inspection it might seem that fluoride, F-, is the correct answer, because it is furthest to the right in period 2. But the question refers to ions: the electron configurations of all four of these ions are identical, 1s2 2s2 2p6. The atomic numbers (Z) are 8, 9,11 and 12, respectively. Magnesium has the highest atomic number (Z = 12), therefore, the valence electrons 'feel' the strongest attraction from the nucleus, so it has the smallest ionic radius. The data supports this: the ionic radii of the ions are: 190, 181, 98, 65 pm for O2-, F-, Na+and Mg2+, respectively.)

Deduce which of the following ions has the smallest ionic radius. a) F- b) Na+ c) Mg2+ d) O2-

a) Iodide ions are displaced to produce aqueous iodine molecules (WHY: chlorine displaces the iodide ions from solution according to the following equation: Cl2 (aq) + 2I− (aq) → 2Cl− (aq) + I2 (aq). Chlorine is more reactive than iodine (it is a more powerful oxidising agent than iodine), therefore, it can displace iodide ions in solution.)

Deduce which of the following occurs when chlorine water is added to an aqueous solution of potassium iodide (KI). a) Iodide ions are displaced to produce aqueous iodine molecules b) Chloride ions are displaced to produce chlorine gas c) No reaction occurs because chlorine and iodine are equally reactive d) No reaction occurs because chlorine is less reactive than iodine

d) Al and O (WHY: Oxygen is the most electronegative element (apart from fluorine) and aluminium is a metal with a lower electronegativity value. This is the only combination involving a metal and a non-metal and so they have the greatest difference in electronegativity.)

Deduce which of the following pairs of elements have the greatest difference in electronegativity. a) Cl and F b) O and F c) C and O d) Al and O

c) II and III (WHY: As the number of occupied energy levels does not increase across a period, there is little change in electron shielding. Ionisation energies increase due to increasing nuclear charge across the period. The atomic radius decreases across the period as the electrons are held more tightly due to the increasing nuclear charge.)

Deduce which of the following periodic trends increases across a period in the periodic table (from left to right). I. Electron shielding II. Ionisation energy III. Nuclear charge IV. Atomic radius a) I and II only b) II, III and IV c) II and III d) I, II and IV

a) I+ < I < I− (WHY: the removal of an electron from an iodine atom to form I+ results in an increase in the attraction between the nucleus and the valence electrons and the radius decreases. The addition of an electron to form I− increases the electron-electron repulsions and decreases the attraction between the nucleus and the valence electrons and the radius increases. Iodine (I) has equal number of protons and electrons.)

Deduce which of the following series represents the correct size order (from smallest to largest atomic/ionic radius) for the various iodine species I, I− and I+. a) I+ < I < I− b) I− < I < I+ c) I < I+ < I− d) I < I− < I+

b) Al3+ (WHY: Na has the electron configuration 1s2 2s2 2p6 3s1 (with 11 protons), Na+ has the electron configuration 1s2 2s2 2p6 (with 11 protons), Mg2+ has the electron configuration 1s2 2s2 2p6(with 12 protons) and Al3+ has the electron configuration 1s2 2s2 2p6 (with 13 protons). The electrons in the aluminium ion experience a stronger attraction from the nucleus as there are 13 protons 'pulling' on 10 electrons. This results in a stronger attraction between the nucleus and the valence electrons and a smaller ionic radius.)

Deduce which of the following species has the smallest radius. a) Na+ b) Al3+ c) Na d) Mg2+

Compounds with the same molecular formula but different arrangement of atoms

Define Structural Isomers

Homolytic Fission is when a bond breaks and each atom gains an electron creating a radical. conditions: UV light Heterolytic fission is when a bond breaks and one atom gains both electrons creating positive and negative ions. conditions: warm

Define homolytic and heterolytic fission and the conditions in which they occur

The standard enthalpy of formation is the enthalpy change involved in the formation of 1 mole of substance from its elements in their standard states at 100 kPa and 298 K.

Define the term standard enthalpy of formation, ∆Hf⦵.

Silicon dioxide has a giant covalent structure in which each silicon atom is central to a tetrahedron of four O atoms. All the atoms are bonded to each other by single covalent bonds.

Describe the structure and bonding in silicon dioxide.

Diamond: covalent bonds (only);Graphite: covalent bonds and the separated layers held together by(weak) London/van der Waals'/dispersion forces;

Diamond, graphite and C60 fullerene are three allotropes of carbon. Compare the bonding in diamond and graphite.

Diamond: 3D array/network involving tetrahedral carbons/each carbon atom joined to four others Graphite: layer structure involving trigonal (triangular) planar carbons/with each carbon atom joined to three others/with hexagonal (six-membered) rings of carbon atoms; C60 fullerene: truncated icosahedrons;Accept carbon atoms form a 'ball' with 32 faces, of which 12 are pentagons and 20 are hexagons, exactly like a soccer ball. Do not accept soccer ball alone.

Diamond, graphite and C60 fullerene are three allotropes of carbon. Describe the structure of each allotrope.

ionic radius

Distance from the center of an ion's nucleus to its outermost electron

trigonal planar, 120

Draw the shape of BF3. State the bond angle and shape of the molecule.

Linear, 180 degrees

Draw the shape of C02. State the bond angle and shape of the molecule.

Tetrahedral, 109.5

Draw the shape of CH4? State the bond angle and shape of the molecule.

Bent, Tetrahedral, 104.5

Draw the shape of H20? State the bond angle and shape of the molecule and the electron geometry.

Trigonal Pyramidal, tetrahedral, 107.5

Draw the shape of NH3? State the bond angle and shape of the molecule and the electron geometry.

Bent, trigonal planar, 119

Draw the shape of SO2? State the bond angle and shape of the molecule and the electron geometry.

electrophile

Electron poor species that can act as Lewis acids and accept electron pairs to form coordinate bonds

b) Two 4s orbital electrons and one 3d orbital electron

Electrons are lost when an iron atom forms the Fe3+ ion. Which combination of electrons is lost? a) Three 4s orbital electrons b) Two 4s orbital electrons and one 3d orbital electron c) One 4s orbital electron and two 3d orbital electrons d) Three 3d orbital electrons

B. X 2+ and Y-

ElementXis in group 2, and element Yin group 7, of the periodic table. Which ions will be present in the compound formed when X and Yreact together? A. X+ and Y- B. X 2+ and Y- C. X+ and Y2- D. X2- and Y+

gas laws

Equations that define how the properties of gases such as temperature, pressure, volume, and amount are released

random errors

Errors that are associated with measurements and are a result of natural variability due to the procedure or instrument used to make the measurement

systematic errors

Errors that result from inaccuracy or bias in the procedure or instrument used to make the measurement

C. 2.8

Ethane burns in oxygen according to the equation below. What volume of oxygen, in dm3, reacts with 0.8 dm3 of ethane? 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l) A. 0.8 B. 1.6 C. 2.8 D. 5.6

Since unsaturated molecules contain double bonds, the double bond breaks during an addition reaction. This allows bromine to attach to the double bond, making them all single bonds. This makes the colour disappear. However, in saturated molecules there are no double bonds, so bromine can't bond to anything meaning the color is still present.

Explain how Bromine water can show whether a molecule is unsaturated or saturated

side with the most gas molecules

Explain how a decrease in pressure changes the position of equilibrium

shifts to the right

Explain how an decrease of the product concentration or a increase of a reactant changes the position of equilibrium

side with the fewest gas molecules

Explain how an increase in pressure changes the position of equilibrium

shifts to the left

Explain how an increase of the product concentration or a decrease of a reactant changes the position of equilibrium

It increases boiling point as the london dispersion forces are stronger and as the chain increases, so does the surface area and the molecular mass meaning more energy is required to break them

Explain how the increasing chain of alkanes affects boiling point.

Decrease in Temperature -> shifts to the left (lower Kc) Increase in Temperature -> shifts to the right (higher Kc)

Explain how the position of equilibrium changes in an endothermic reaction when the temperature increases and decreases. how does the Kc change as well

Increase in Temperature -> shifts to the left (lower Kc) Decrease in Temperature -> shifts to the right (higher Kc)

Explain how the position of equilibrium changes in an exothermic reaction when the temperature increases and decreases. how does the Kc change as well

One or more of the groups of hydrogen is replaced by an electrophile. An electrophile is a reactant that are themselves electron deficient. They have a positive change and they see the benzene ring as an electron donor to gain a full outer shell.

Explain substitution in Benzene

-Triangular Planar (120) - bonds are 120 - symmetrical - p-orbitals haven't bonded which means they overlap and create a donut like structure -> allow delocalisation in the ring

Explain the features of Benzene

Initiation: Homolystic fusion - Each chlorine atom receives one of the electrons in the Cl-Cl bond: Cl-Cl -> 2 Cl• Propagation: The radicals then react with methane molecule. Methyl radicals are produced. The methyl radicals reacts quickly with a Cl2 molecule: CH4 + Cl• -> •CH3 + HCl -> •CH3 + Cl2 -> CH3Cl + Cl• Termination: The process is terminated when two radicals reacts together to make a relatively unreactive molecule: Cl• + Cl• -> Cl2

Explain the three steps of substitution of alkanes

It increases because the electronegativity increases from left to right each period. This is because there are more electrons which means it has a stronger pull.

Explain this graph

This has to do with the sub-energy levels. The points at the top are half-full meaning they are more stable, so more energy is needed to get rid of an electron. First ionisation energies generally increase across a period and decrease down a group in the periodic table (Figure 1). The increase in ionisation energy across a period is due to the increase in nuclear charge and decrease in atomic radii. This results in an increased attraction between the nucleus and the valence electrons. The decrease in ionisation energy down a group is due to the increase in atomic radius. The increased distance results in a weaker attraction between the nucleus and the valence electrons of an atom.

Explain this graph, why are the lines up and down

Acids undergo neutralisation reactions with alkalis and bases such as metal hydroxides, metal oxides and aqueous ammonia to produce a salt and water. The general word equations are given below, together with some specific examples: metal oxide + acid → salt and water metal hydroxide + acid → salt and water CuO (s) + H2SO4 (aq) → CuSO4 (aq) + H2O (l) NaOH (aq) + HNO3 (aq) → NaNO3 (aq) + H2O (l) CuO (s) + 2CH3COOH (aq) → Cu(CH3COO)2 (aq) + H2O (l) NH3 (aq) + HNO3 (aq) → NH4NO3 (aq)

Explain what happens when a base reacts with a metal oxide. Use a formula to explain

In a neutralisation reaction, an acid reacts with a base (or an alkali) to produce a salt and water. The reaction between an acid and a base is exothermic, meaning that heat is released and the enthalpy change (ΔH) is negative. The general word equation for a neutralisation reaction is: acid + base (or alkali) → salt + water HCl + NaOH -> NaCl + H2O

Explain what happens when an acid reacts with a base. Use a formula to explain

Acids react with metal carbonates or metal hydrogencarbonates to produce a salt, carbon dioxide gas and water. The general word equations are given below, together with some specific examples. metal hydrogencarbonate + acid → salt + water + carbon dioxide NaHCO3 (s) + HCl (aq) → NaCl (aq) + H2O (l) + CO2 (g)

Explain what happens when an acid reacts with a hydrogen carbonate. Use a formula to explain

Acids react with metal carbonates or metal hydrogencarbonates to produce a salt, carbon dioxide gas and water. The general word equations are given below, together with some specific examples. metal carbonate + acid → salt + water + carbon dioxide MgCO3(s) + 2HCl (aq) → MgCl2 (aq) + H2O (l) + CO2 (g)

Explain what happens when an acid reacts with a metal carbonate. Use a formula to explain

Acids undergo reactions with active metals to produce a salt and hydrogen gas. metal + acid → salt + hydrogen Zn (s) + 2HNO3 (aq) → Zn(NO3)2 (aq) + H2 (g) Ca (s) + H2SO4 (aq) → CaSO4 (aq) + H2 (g) Mg (s) + 2CH3COOH (aq) → (CH3COO)2Mg (aq) + H2 (g)

Explain what happens when an acid reacts with a metal. Use a formula to explain

Electronegativity is the attraction an atom has for the bonding pair of electrons in a covalent bond. Fluorine is a smaller atom than chlorine and so the bonding pairs of any covalent bond it is taking part in are closer to the nucleus and experience a greater attractive force. There is also less shielding of the bonding electrons by electrons in inner energy levels in the case of fluorine.

Explain what is meant by the term electronegativity and explain why the electronegativity of fluorine is greater than that of chlorine.

For the free atom the 4s sub-energy level is lower than the 3d sub-energy level and so is filled first. Once an ion is formed the positive nucleus attracts the electron energy levels more strongly and the 3d sub-level becomes lower in energy than the 4s sub-level so the 4s electron is removed leaving a full 3d sub-energy level.

Explain why a potassium atom contains an electron in a 4s orbital with no electrons in a 3d orbital whereas a copper(I) ion, Cu+ has the electronic configuration [Ar]3d10 with no electrons in the 4s orbital.

For an ionic compound to conduct electricity the ions must be free to move to the electrodes and be discharged. In the solid state the ions are held in a strong lattice and are not free to move. The solid cannot conduct electricity. When molten the ions become free to move and the compound can conduct electricity.

Explain why an ionic solid such as lithium fluoride does not conduct electricity until it is heated above its melting point.

The three p orbitals are of equal energy and are orthogonal to each other. The px orbital lies along the x-axis, py lies along the y-axis and pz lies along the z-axis.

Explain why it is important to label the x,y and z axes when drawing out the shape of a p orbital.

Monomers are smaller molecules with a smaller surface areas with weaker intramolecular forces (london dispersion)

Explain why monomers are often gases or volatile liquids, but polymers are solid.

The smell between strong acids/bases and weak acids/bases is another way of telling the difference. A weak acid/base has a much stronger smell compared to a strong acid/base, which have no smell. This is due to the fact that strong acids/bases only fully dissociate in water. Therefore, ions are produced. Ions don't evaporate and therefore we can't smell anything. On the other hand, weak acid/bases only partially dissociate. Therefore, not all of the solution turns into ions. The ones that don't turn into ions, evaporate and produce a smell.

Explain why strong and weak acids/bases smell very different

bonds are polar as Cl more electronegative than Si; Allow "electronegativities are different" molecule is symmetrical, hence polar effects cancel out/OWTTE;

Explain why the bonds in silicon tetrachloride, SiCl4, are polar, but the molecule is not.

The magnesium atom has a greater nuclear charge as it has an extra proton compared to the sodium atom. Consequently, the atomic radius is smaller as there is a stronger attraction for the electrons by the nucleus.

Explain why the first ionization energy of magnesium is greater than that of sodium

The bromine atom has one more proton in its nucleus than a selenium atom. This means that the outer, valence electrons, which are in the same energy level in both atoms, are attracted more strongly in the bromine atom. When the negative ions are formed the Br atom gains one electron, but the Se atom gains two. The repulsion between these added electrons increases the size of the ion compared to the atom and this effect is greatest in the case of Se.

Explain why the ionic radius of bromine is less than that of selenium.

Most noble gases have full valence shells. Because of their full valence electron shell, the noble gases are extremely stable and do not readily lose or gain electrons.

Explain why the noble gases could be at zero on this graph

The structure of the NO2 molecule is V-shaped (bent) and this means that there is an unsymmetrical distribution of charge as the O atoms are more electronegative than the N atom. The carbon dioxide molecule in linear and though each bond is polarised there is no overall dipole as the equal and opposite effects cancel each other.

Explain, using diagrams, why NO2 is a polar molecule but CO2 is a non-polar molecule.

C. They must collide with the correct geometry or orientation.

For two particles to react when they collide what must be true according to collision theory? A. They must both have the same kinetic energy. B. All their chemical bonds must be broken. C. They must collide with the correct geometry or orientation. D. They must be in the gaseous or liquid state.

C. Br(g) + e- → Br-(g)

For which of the following is the sign of the enthalpy change different to the other three? A. Br2(g) → 2Br(g) B. Br(g) → Br+(g) + e- C. Br(g) + e- → Br-(g) D. Br(l) → Br(g)

If there is a distinct smell of a substance it indicates that it is evaporating, which shows it has a low boiling point.

How can the smell of a substance indicate it is an alcohol?

The presence of carbon dioxide gas can be tested for by bubbling the gas through an aqueous solution of calcium hydroxide, Ca(OH)2 (aq), otherwise known as limewater. If carbon dioxide gas is present, the limewater turns a 'milky' colour as a solid precipitate of calcium carbonate is formed.

How can you test the presence of CO2 (g) in a reaction between an acid and a hydrogen/metal carbonate?

The sample to be analysed is first vaporised to form a gas. Next, it is bombarded by high-energy electrons, producing positive ions, which are then accelerated in an electric field. Note that a mass spectrometer produces ions with a one positive (1+) charge. The positive ions are deflected in a magnetic field depending on their mass to charge ratio (m/z or m/e). Ions with a higher mass to charge ratio are deflected less in the magnetic field than ions with a lower mass to charge ratio. Finally, the positive ions reach the detector, where they produce a mass spectrum. Note

How does the mass spectrometer works?

C. 9.0 x 10^23

How many molecules are present in 27.0 g of distilled water? A. 2.7 x 10^24 B. 1.5 C. 9.0 x 10^23 D. 4.5

D. 2.7 x 10^24

How many oxygen atoms are present in 0.5 mole of pentahydrated copper(II) sulfate, CuSO4.5H2O? (Avogadro's constant = 6 x 1023 mol-1) A. 2.5 B. 4.5 C. 3.0 x 10^23 D. 2.7 x 10^24

D. 140 kJ

How much energy is released when 14.0 g of carbon monoxide are completely combusted? 2CO(g) + O2(g) → 2CO2(g) ∆H = - 560 kJ A. 1120 kJ B. 560 kJ C. 280 kJ D. 140 kJ

Naming esters...basically the alcohol gives the '-yl' part and the acid the '-oate' part

How to name esters?

b) I and II only (WHY: most non-metals have low melting and boiling points because they are simple molecular substances, so III is incorrect. The other two statements are generally correct; non-metal elements are poor conductors of heat and electricity and form negative ions by gaining electrons to achieve a full outer shell.)

Identify which of the following properties is/are typical of the non-metal elements in period 3 of the periodic table. I. They are poor conductors of both heat and electricity II. They form negative ions by gaining one or more electrons III. They have high melting points and boiling points a) II and III only b) I and II only c) I and III only d) I, II and III

These trends happens because alkali metals want to lose one more electron so they to lose it, while halogens want to gain one more electron they form negative ions, so they can gain one more electron.

In part 1 you have observed that alkali metals have a tendency to form positive ions with charge 1. In part 2 you have seen that halogens have a tendency to form negative ions with charge 1. How can you explain these trends?

d) Atomic number

In the modern periodic table the elements are arranged in increasing order of which important feature of their atoms? a) Isotopic mass b) Relative atomic mass c) Nucleon number d) Atomic number

D. N2, N2H2, N2H4

In the molecules N2H4, N2H2, and N2, the nitrogen atoms are linked by single, double and triple bonds, respectively. When these molecules are arranged in increasing order of the lengths of their nitrogen to nitrogen bonds (shortest bond first) which order is correct? A. N2H4, N2, N2H2 B. N2H4, N2H2, N2 C. N2H2, N2, N2H4 D. N2, N2H2, N2H4

d) O < F < Ne

In which of the following series of elements are the atoms arranged in order of increasing first ionisation energy? a) Be < Mg < Ca b) Be < B < C c) Ne < O < F d) O < F < Ne

1. Temperature: A higher temperature causes particles to move more quickly, which leads to more collisions. Also, at higher temperature more particles have an energy ≥ Ea. Both effects cause the reaction rate to increase. 2. Concentration or pressure: A higher concentration of reactants in solution means the reactant particles are more densely packed, which leads to more collisions. This causes the reaction rate to increase. The same applies to an increase of pressure for gases. 3. Particle size: The smaller the particle size, the larger the surface area exposed as contact area for reaction. Therefore, the rate of reaction decreases with particle size and increases with surface area. 4. Catalysts: Catalysts increase the rate of reaction by lowering the activation energy of the reaction, so that more particles have an energy ≥Ea.

List and explain four factors that influence the rate of reaction.

2Li(s) + 2H2O(l) → 2LiOH(aq) + H2(g) The lithium moves around the surface of the water and there is a fizzing as a colourless gas is given off. The metal eventually disappears.

Lithium reacts with water. Write an equation for the reaction and state two observations that could be made during the reaction

B. MP

Metal M shows only one oxidation state when it forms compounds. The formula of the oxide of M is M2O3? Which is the correct formula for another of the compounds M forms? A. M3P2 B. MP C. M2P D. M2P3

Amines

NH2

On the Maxwell-Boltzmann diagram decide which curve had a higher temperature

Amides

Organic compounds whose molecules have a carbonyl nitrogen bond. They are the product formed in a reaction between a carboxylic acid and an amine.

Esters

R-COO-R

Aldehydes

RCHO -al - An organic molecule with a carbonyl group located at the end of the carbon skeleton.

1.P is proportionate to T. 2.P is proportionate to 1/V. 3. V is proportionate to T.

Sketch the graphs that show the relationship between: Pressure and temperature. Pressure and volume. Volume and temperature.

1. Lowering the temperature means slowing the particles down, so that fewer particles will have an energy ≥ Ea. 2. Slowing the particles down also means that there will be less frequent collisions. Both actions cause the rate of reaction to slow down. Next time you put food in the refrigerator think about how this influences the reactions of decay on a molecular level!

State and explain two ways in which lowering the temperature influences the reaction rate.

The reaction rate is the change in the concentration of a reactant or product per unit of time.

State the definition of reaction rate.

Neon

State the name of the element in period 2 that has the highest effective nuclear charge. Answer with thename of the element (not the symbol).

Sodium hydroxide, dilute and warm

State the name of the reagent and condition needed for nucleophilic substitution

Hydrogen bromide

State the name of the reagent needed for free-radical substitution

any three of the following possible answers: size of the positive) charge (on the ion); mass (of the ion); strength of the magnetic field; velocity/speed (of the ions) strength of the electric field

State three factors that affect the degree of deflection of ions in a mass spectrometer.

manufacturing of alcohol, synthesis of ethanoic acid, polymerisation of ethene to make PVC

State two industrial uses of ethene

M+(g)→M2+(g)+e−M+(g)→M2+(g)+e−

State what is meant by the term second ionization energy.

the octet rule

States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons

d) 29

The M2+ ion of a metal in the first row of the d-block of elements has an electron configuration of [Ar]3d9. What is the atomic number (Z) of this metal? a) 27 b) 28 c) 30 d) 29

Electronegativity

The ability of an atom to attract the shared electrons in a covalent bond

specific heat capacity

The amount of heat needed to raise the temperate of 1g of a substance by 1 kelvin.

C. 391

The bond enthalpies for N≡N and H—H are 945 kJ mol-1 and 436 kJ mol-1 respectively. When nitrogen and hydrogen react to form ammonia the enthalpy change is - 92 kJ. N2(g) + 3H2(g) → 2NH3(g) ∆H = - 92 kJ What is the average bond enthalpy (in kJ) for the N―H bond? A. 212 B. 424 C. 391 D. 782

London (dipersion) forces

The electrostatic attraction between instantaneous dipoles on one molecule and induced dipoles on another

dipole-dipole

The electrostatic attraction between permanent dipoles on two molecules

Bond Enthalpy

The energy required to break one mole of a particular bond in the gaseous state

ionization energy

The energy required to remove one mole of electrons from one mole of atoms in a gaseous state

A. +9kJ

The enthalpy change for the dimerisation of two mol of nitrogen dioxide to form one mol of dinitrogen tetroxide is − 57 kJ. 2NO2(g) → N2O4 ∆H = − 57 kJ The enthalpy change for the formation of one mol of NO2(g) from its elements is + 33 kJ 1⁄2N2(g) + O2(g) → NO2(g) ∆H =+33kJ What is the enthalpy change for the formation of one mol of dinitrogen tetroxide from its elements? N2(g) + 2O2(g) → N2O4(g) A. +9kJ B. -9kJ C. +24kJ D. -24kJ

enthalpy of reaction

The enthalpy change that occurs when one mole of a substance is reacted under standard conditions.

Standard enthalpy of formation

The enthalpy change that occurs when one mole of the substance is formed from its elements in their standard states under standard conditions.

D. - 1400 kJ

The enthalpy changes for the formation of one mol of each of the two oxides of phosphorus from their elements are given below: P4(s) + 3O2(g) → P4O6(s) ∆H = - 1600 kJ P4(s) + 5O2(g) → P4O10(s) ∆H = - 3000 kJ What is the enthalpy change for the oxidation of one mol of P4O6 to form P4O10? P4O6(s) + 2O2(g) → P4O10(s) A. - 4600 kJ B. + 4600 kJ C. + 1400 kJ D. - 1400 kJ

The formula of iron(III) sulfate is Fe2(SO4)3. What is the total number of ions represented in this formula? a) 3 b) 2 c) 6 d) 5

A. 28.8 kJ

The heat capacity of manganese is 0.480 kJ kg K . How much energy is required to raise the temperature of 3.00 kg of manganese by 20.0 K? A. 28.8 kJ B. 3.20 kJ C. 0.0720 kJ D. 288 kJ

B. 250 x 4.2 x 14 / 0.010

The heat produced when 0.010 mol of propanone was combusted raised the temperature of 250 g of water by 14C. The specific heat capacity of water is 4.2 J g-1 K-1. Which is the correct expression for value of the enthalpy of combustion of propanone (in J mol-1)? A. 250 x 4.2 x 287 / 0.010 B. 250 x 4.2 x 14 / 0.010 C. 0.010 x 4.2 x 287 / 250 D. 250 x 4.2 x 14 x 0.010

relative atomic mass

The mass of an atom of an element relative to the mass of an atom of carbon-12. The relative atomic mass has the symbol Ar, and it has no units.

relative molecular mass

The mass of one unit of a covalent compound expressed relative to the mass of an atom of carbon-12. It has the symbol Mr, and it has no units.

Avogadro's Law

The same volume of any gas at the same temperature and pressure will contain the same number of gas particles

The general trend is for boiling points to increase going down the group; this is shown by the values for PH3, AsH3 and SbH3. This is because the number of electrons in each molecule increases as Mrincreases, and so the strength of the dispersion forces between the molecules increases meaning that it requires more energy to disrupt these forces in the liquid. However, ammonia has a higher boiling point than expected on this basis. This is due to the presence of hydrogen bonding between the molecules. Such additional forces are not present in the other cases.

The trend in the boiling points of the hydrides of group 15 is shown in the graph below. Discuss the reasons for the variation in the boiling points of this series of compounds.

In diamond the carbon atoms are arranged in a three-dimensional lattice structure in which all the atoms are linked by single covalent bonds. The atoms are arranged tetrahedrally in the lattice and there are no weak points in the structure, meaning that diamond is very hard. All the outer (valence) electrons of the carbon atoms are involved in bonding so there are no electrons free to move through the structure under the influence of an electrical field. Graphite consists of layers of covalently bonded carbon atoms arranged in interlinked hexagonal rings. These layers are stacked on top of each other in the crystal but the forces between the layers are weak dispersion forces and the layers can slide over each other making graphite soft. Only three of the valence electrons of each carbon atom are involved in the covalent bonding of the layers. The fourth electron of each atom is involved in a delocalized p cloud extending between the layers. These electrons are free to move and are responsible for the electrical conductivity of graphite.

The type of bonding present in an element or compound can be used to explain its physical properties. Use your understanding of the key features of different types bonding and structure to explain the following: Explain why one form of carbon (diamond) is a very hard substance that does not conduct electricity whereas another form of carbon (graphite) is very soft and a good electrical conductor.

Ionic lattice

Three-dimensional network of positively and negatively charged ions

conjugate acid-base pair

Two species with chemical formulas that differ by H+

The most frequently found energy is the amount of energy with the highest probability (the top of the peak).

Use the Maxwell-Boltzmann diagram below to deduce the most frequently found energy of the particles in the system.

Reaction rates increase with increasing temperatures. Note that the graph starts steeper due to the faster initial reaction rate. The graph reaches the maximum amount of gas produced sooner. The total volume of gas produced does not change as the amounts of reactant remain the same.

Use the graph below to sketch the graph of the same reaction taking place at a higher temperature.

UV Light

What activates free radical substitution?

B. 2.0

What amount of carbon dioxide (in mol) will be formed when 32.0 g of methane, CH4, burns completely in oxygen? A. 1.0 B. 2.0 C. 4.0 D. 8.0

B. Delocalized valence electrons

What are responsible for the high electrical conductivity of metals? A. Delocalized positive ions B. Delocalized valence electrons C. Delocalized atoms D. Delocalized negative ions

HCO3, HSO4, H2PO4, HPO4^2

What are some examples of amphiprotic species?

Aqueous base + Gently warmed (quite slow at room temperature)

What are the conditions of a nucleophilic reaction?

heat and H+ catalyst

What are the conditions to create an ester in a condensation reaction?

-successive members of a homologous series differ by a CH2 group -members of the homologous series can be represented by the same general formula -differ by -CH2- group and have longer chains -As it grows larger the boiling point, viscosity, and density increases

What are the main features of a homologous series of alkanes?

Chlorine - chloro; Flourine - flouro; Iodine - iodo; Bromine - bromo

What are the suffixes for halogenalkanes?

When an alkali metal comes in contact with a halogen the reaction is very rigorous and it produces a salt.

What do you expect will happen when an akali metal comes into contact with a halogen?

charge of the nucleus, shielding (attraction of an outer electron to the nucleus is blocked by other electrons)

What factors effect the ionization energy?

aldehyde --(warm + H20)--> carboxylic acid

What forms when a primary alcohol is oxidised?

ketone

What forms when a secondary alcohol is oxidised?

B. Each sodium atom loses one electron.

What happens when sodium and oxygen combine together? A. Each sodium atom gains one electron. B. Each sodium atom loses one electron. C. Each oxygen atom gains one electron. D. Each oxygen atom loses one electron.

B. London (dispersion) forces

What intermolecular forces are present in fluorine gas? A. Dipole-dipole attractions B. London (dispersion) forces C. Covalent bonds A. Hydrogen bonds

what type of element it forms

What is melting point influenced by?

CO2 + H20

What is produced in a combustion reaction?

CO + H20

What is produced in a incombustion reaction?

A. AB

What is the correct formula for an ionic compound formed between a Group 2 element, A, and a Group 16 element, B. A. AB B. A2B6 C. AB3 D. A3B

Sn1 -> occurs at different times and only on tertiary alcohols (the nucleophile attacks at the same time as the C-X bond breaks) Sn2 -> occurs at the same times and only on primary alcohols (the C-X bond breaks and then the nucleophile attacks)

What is the difference between Sn1 and Sn2?

D. Ca3N2

What is the formula for the compound formed by calcium and nitrogen? A. CaN B. Ca2N C. Ca2N3 D. Ca3N2

HCl(aq) à H+(aq) + Cl-(aq)

What is the formula for the dissociation of a strong acid?

NaOH + H20 -> OH- + Na+

What is the formula for the dissociation of a strong base?

CH3COOH(aq) + H2O(l) ⇄ CH3COO-(aq) + H+(aq)

What is the formula for the dissociation of a weak acid?

NH3(aq) + H2O(l) ⇄ NH4+(aq) + OH-(aq)

What is the formula for the dissociation of a weak base?

B. Al2O3

What is the formula of the compound formed when aluminium reacts with oxygen? A. Al3O2 B. Al2O3 C. AlO2 D. AlO3

B. It increases the initial rate of reaction.

What is the function of solid vanadium pentoxide in the Contact process? A. It moves the position of equilibrium in favour of more products. B. It increases the initial rate of reaction. C. It lowers the enthalpy change for the reaction. D. It increases the yield of products formed.

D. Delocalized outer electrons

What is the high electrical conductivity of metals due to? A. Delocalized atoms B. Delocalized negative ions C. Delocalized positive ions D. Delocalized outer electrons

What is the maximum amount of methanol, in mol, that could be formed when 4 mol of carbon dioxide and 6 mol of hydrogen gas are placed in a container and react according to the equation below? CO2(g) + 3H2(g) → CH3OH(l) + H2O(l) A. 1 B. 2 C. 3 D. 4

B. 28

What is the maximum mass of iron, in tonnes, that can be obtained when 40 tonnes of iron(III) oxide, Fe2O3 (Mr = 160), are reduced in a blast furnace according to the equation below? Fe2O3 + 3CO → 2Fe + 3CO2 A. 14 B. 28 C. 56 D. 80

B. 8.0

What is the maximum mass, in grams, of magnesium oxide that can be formed when 4.8 g of magnesium reacts with oxygen? A. 4.8 B. 8.0 C. 11.2 D. 12.8

a) A period

What is the name given to a horizontal row of elements in the periodic table? a) A period b) A group c) A cluster d) A block

Alkynes (alkynyl)