Chemistry Topic 4 - Exam Style Questions
(a) In benzene each carbon atom has three electron domains (all bonding) so the bond angles will all be approximately 120o. (b) In cyclohexane each carbon atom has four electron domains (all bonding) so the bond angles will all be approximately 109.5o.
(a) A simplified model of benzene, C6H6, shows the six carbon atoms in a ring with alternate single and double bonds between the carbon atoms. Each carbon atom is also bonded to one hydrogen atom. Based on this model predict the C-C-C bond angle in benzene. (b) In cyclohexane, C6H12 the six carbon atoms are also in a ring but are joined to each other only by single bonds. Each carbon atom is also bonded to two hydrogen atoms. Predict the C-C-C bond angle in cyclohexane.
d)
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
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.
(i) 109.5°; 1 (ii) NH4+ has four bonding pairs (around central atom so is a regular tetrahedron);NH3 has three bonding pairs (of electrons) and one non-bonding pair; non-bonding pairs (of electrons) exert a greater repulsive force;
Ammonia reacts with hydrogen ions forming ammonium ions, NH4+. (i) State the H-N-H bond angle in an ammonium ion. (ii) Explain why the H-N-H bond angle of NH3 is different from the H-N-H bond angle of NH4+; referring to both species in your answer.
Suitable diagram indicating dipoles; lone pairs of electrons; hydrogen bonding;
An important compound of nitrogen is ammonia, NH3. The chemistry of ammonia is influenced by its polarity and its ability to form hydrogen bonds. Polarity can be explained in terms of electronegativity. Draw a diagram to show hydrogen bonding between two molecules of NH3.The diagram should include any dipoles and/or lone pairs of electrons
(relative) measure of an atom's attraction for electrons; in a bond;
An important compound of nitrogen is ammonia, NH3. The chemistry of ammonia is influenced by its polarity and its ability to form hydrogen bonds. Polarity can be explained in terms of electronegativity. Explain the term electronegativity.
molecule is asymmetrical/OWTTE;
An important compound of nitrogen is ammonia, NH3. The chemistry of ammonia is influenced by its polarity and its ability to form hydrogen bonds. Polarity can be explained in terms of electronegativity. Explain why the ammonia molecule is polar.
107°
An important compound of nitrogen is ammonia, NH3. The chemistry of ammonia is influenced by its polarity and its ability to form hydrogen bonds. Polarity can be explained in terms of electronegativity. State the H-N-H bond angle in an ammonia molecule.
Chlorine (3.2) is more electronegative than carbon (2.6). This means the shared pair of bonding electrons is closer to the chlorine atom resulting in a polar bond.
Use information in Section 8 of the IB chemistry data booklet to explain why a carbon to chlorine bond is polar.
C=O bonds are polar due to the greater electronegativity of oxygen compared to carbon so the electrons in the C=O bond are drawn closer to the oxygen atom. The carbon dioxide molecule is non-polar as the resultant polarity of the two oppositely opposed dipoles from the two C=O bonds is zero.
Carbon dioxide is a linear molecule. It contains two carbon to oxygen double bonds at 180o to each other. Explain why the C=O bonds are polar and yet the molecule is non-polar.
Bromine consists of individual Br2 molecules in which the atoms are held together by a single covalent bond formed by a shared pair of outer electrons. The forces between the molecules in the liquid consist of relatively weak interactions between temporary dipoles in the molecules known as London (dispersion) forces.
Describe the bonding within and between the molecules of liquid bromine.
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.
Both diamond and silicon have a giant tetrahedral structure but C-C bonds are stronger than Si-Si bonds so are harder to break.
Describe the structures of both diamond and silicon and suggest why silicon has a lower melting point than diamond.
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.
bent/V shaped/angular, 104.5°; repulsion of the two non-bonding pairs of electrons forces bond angleto be smaller/non-bonding pairs repel more than bonding pairs;
Draw a Lewis structure of a water molecule, name the shape of the molecule and state and explain why the bond angle is less than the bond angle in a tetrahedral molecule such as methane.
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.
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+
The oxygen atom in water contains two non-bonding pairs of electrons. One of these forms a dative bond with the proton (which is extremely small as it has no electrons).
Explain why a proton in water, H+(aq) is often written as H3O+(aq)
The white precipitate is silver chloride formed from the reaction of silver ions with chloride ions. Ag+(aq) + Cl-(aq) → AgCl(s) All the chlorine atoms in tetrachloromethane are covalently bonded so no chloride ions are present to precipitate with silver ions.
Explain why a white precipitate is formed when silver nitrate solution is added to a solution of potassium chloride but not when silver nitrate solution is added to tetrachloromethane.
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.
Both diamond and graphite have giant molecular structures consisting of strong covalent bonds so they have high melting points. In diamond all the C to C bonds are equal and all the electrons are held in fixed positions arranged tetrahedrally around each carbon atom. In graphite three of the C to C bonds are fixed in a hexagonal shape with bonds angels of 120o to give a flat layer. The layers are held together by weak bonds consisting of delocalised electrons. These delocalised electrons are free to move between the layers so that graphite is a good conductor of electricity.
Explain why graphite and diamond both have very high melting points (in the region of 4000 oC) and yet diamond is a poor electrical conductor whereas graphite is a good electrical conductor.
Silicon dioxide has giant molecular structure with strong covalent bonds resulting in a high melting point. Carbon dioxide contains individual molecules of carbon dioxide held together by weak intermolecular forces which are easily broken so it has a low melting point.
Explain why silicon dioxide has a high melting point (above 1600 OC) whereas carbon dioxide is a gas at room temperature and pressure.
The sulfur atom in SO2 contains three electron domains arranged to give a trigonal planarshape. The two bonding electron domains to the oxygen atoms give the molecule its bentshape with an angle of approximately 120o. In carbon dioxide there are only two electron domains (both bonding) around the central carbon atom so the molecule is linear.
Explain why sulfur dioxide molecules, SO2, have a bent shape whereas carbon dioxide molecules, CO2, are linear.
Ammonia contains one non-bonding pair of electrons around the central nitrogen atom. This exerts a greater repulsion than the three bonding pairs so the H-N-H bond angle will be less than 109.5o. In the ammonium ion the four bonding pairs of electrons around the central nitrogen atom give the ion a regular tetrahedral shape with a bond angle of 109.5o.
Explain why the H-N-H angle in ammonia is smaller than the H-N-H angle in the ammonium ion.
Oxygen has the electron configuration 1s22s22p4. When two oxygen atoms combine to form oxygen gas each atom needs to share two more electrons so the bond between the atoms is made from two shared pairs of electrons so that each atom attains the electron configuration a noble gas. Nitrogen has the electron configuration 1s22s22p3. Each nitrogen atom needs to share three electrons with the other nitrogen atom to form a triple bond (three shared pairs of electrons) between the two atoms so that both achieve a noble gas electron configuration.
Explain why the bond between two oxygen atoms in oxygen gas is a double bond whereas the bond between two nitrogen atoms in nitrogen gas is a triple bond.
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.
Ethyne contains a triple covalent bond whereas ethene contains a double covalent bond between the carbon atoms. The more electron pairs involved in the bonding the stronger and shorter the bond as the two nuclei are attracted more strongly together.
Explain why the carbon to carbon bond in ethyne, C2H2, is stronger and shorter than the carbon to carbon bond in ethene, C2H4.
Ethanoic acid contains one C=O double bond and one C-O single bond. The double bond is shorter than the single bond.
Explain why there are two different carbon to oxygen bond lengths in a molecule of ethanoic acid
Water is a polar molecule as it has a bent shape and polar O-H bonds. These are given energy by the oscillating microwaves as they continually try to line up with the field and so heat up. Tetrachloromethane is made up of non-polar molecule as the resultant polarity of the four symmetrical C-Cl bonds is zero. The molecules are thus unaffected by the microwave radiation.
Explain why water in a beaker heats up quickly in a microwave oven whereas when the same volume of tetrachloromethane, CCl4(l), is placed in the beaker and the microwave switched on for the same length of time there is no increase in the temperature of the tetrachloromethane.
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.
HF is polar as the molecule only contains two atoms with different electronegativity values. H2O is polar as the molecule is bent and contains a dipole (see right). CF4 is tetrahedraland CO2 is linear; in both cases the bond polarities cancel out to give a zero resultant dipole.
Fluorine and oxygen are very electronegative elements. Explain why hydrogen fluoride, HF, and water, H2O, are very polar molecules but tetrafluoromethane, CF4, and carbon dioxide, CO2 are non- polar.
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
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
Three resonance structures for the carbonate ion can be drawn. Each contains one C=O double bond from the carbon atom to different oxygen atoms so that the average bond order for the carbon to oxygen bond is 4/3 and all the carbon to oxygen bonds are the same length and strength.
One Lewis structure for the carbonate ion, CO32-, shows one double C=O bond and two single C-O bonds. Explain why the bond lengths of all the carbon to oxygen bonds in the carbonate ion are equal.
find number of electron pairs/charge centres in (valence shell of) central atom;electron pairs/charge centres (in valence shell) of central atom repel each other; to positions of minimum energy/repulsion/maximum stability; pairs forming a double or triple bond act as a single bond; non-bonding pairs repel more than bonding pairs/OWTTE;
Outline the principles of the valence shell electron pair repulsion (VSEPR) theory.
BF3, N2O, P4O6 and CBr4;Non-metals only/smalldifference in electronegativity values of the elements;
Predict and explain which of the following compounds consist of molecules:NaCl, BF3, CaCl2, N2O, P4O6, FeS and CBr4.
(a) BCl3 contains 3 bonding electron pairs around the central boron atom so the shape will be trigonal planar with angles of 120o. (b) POCl3 contains 4 bonding electron domains so tetrahedral with angles of approximately 109.5o. In fact the Cl-P-Cl bond angle is 103o (see right) (c) PH3 contains 3 bonding & 1 non-bonding electron pairs so trigonal pyramidal with bond angles of approximately 107o (the actual value is 93.5o) (d) HCN contains two electron domains around the central carbon atom so linear with bond angles of 180o.
Predict the shape and bond angles of: (a) boron trichloride, BCl3 (b) phosphoryl chloride, POCl3 (c) phosphine, PH3 (d) hydrogen cyanide, HCN
NH4Cl
State the formula of ammonium chloride.
Li2O
State the formula of lithium oxide.
Mg(ClO3)2
State the formula of magnesium chlorate.
the octet rule
States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons
The phenyl group is essential a substituted benzene ring. It can be shown as two resonance structures in which the double and single C to C bonds alternate. Since all six C to C bonds are of equal length and strength a circle in the phenyl ring illustrates this better than showing alternate double and single bonds which would be of different length and strength.
Suggest a reason why diagrams of organic structures containing a phenyl ring often show the phenyl ring as a hexagon with a circle inside rather than as a hexagon with alternate double and single bonds.
Aluminium chloride, AlCl3, is covalent and there are only six electrons around the central aluminium atom. When it dimerises one of the chlorine atoms from another AlCl3 molecule forms a coordinate bond with the aluminium atom so that each aluminium atom now obeys the 'octet rule'.
Suggest why aluminium chloride, AlCl3, readily dimerises to form Al2Cl6.
ionic bonding
The electrostatic attraction between oppositely charged ions
covalent bonding
The electrostatic attraction between positive nuclei and shared pairs of bonding electrons.
d
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
Ozone can be drawn as two resonance hybrids in which the bond order for the O to O bond is 3/2. This means that the O to O bond in ozone is weaker than the O=O double bond in oxygen so less energy is required to break it.
The oxygen to oxygen bonds in oxygen, O2(g) and ozone, O3(g) are both broken down by ultraviolet light in the atmosphere. Suggest why higher energy ultraviolet light is required to break the oxygen to oxygen bond in oxygen gas compared to the oxygen to oxygen bond in ozone gas.
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.
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
D. MgSO4 and AlP
What are the correct formulas for magnesium sulfate and aluminium phosphide? A. Mg(SO4)2 and AlPO4 B. MgSO4 and AlPO4 C. Mg(SO4)2 and AlP D. MgSO4 and AlP
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
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
D. Ca3N2
What is the formula for the compound formed by calcium and nitrogen? A. CaN B. Ca2N C. Ca2N3 D. Ca3N2
B. Al2O3
What is the formula of the compound formed when aluminium reacts with oxygen? A. Al3O2 B. Al2O3 C. AlO2 D. AlO3
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
B. The shapes of molecules and ions
What is the valence shell electron pair repulsion (VSEPR) theory used to predict? A. The energy levels in an atom B. The shapes of molecules and ions C. The electronegativities of elements D. The type of bonding in compounds
bent shape
What shape is this?
tetrahedral shape
What shape is this?
A. covalent >hydrogen >van der Waals'
When the following bond types are listed in decreasing order of strength (strongest first), what is the correct order? A. covalent >hydrogen >van der Waals' B. covalent >van der Waals' >hydrogen C. hydrogen >covalent >van der Waals' D. van der Waals' >hydrogen >covalent
D. NH4Cl
Which compound contains bothionic and covalent bonds? A. MgCl2 B. HCl C. H2CO D. NH4Cl
C. CH3COOH
Which compound dissolves in water to form a solution that conducts electricity? A. C2H5OH B. CH3COCH3 C. CH3COOH D. CH3COOCH3
B. The electrostatic attraction between positive ions and negative ions
Which describes ionic bonding best? A. The electrostatic attraction between nuclei and pairs of electrons B. The electrostatic attraction between positive ions and negative ions C. The electrostatic attraction between a positive ion and an electron D. The electrostatic attraction between protons and electrons
B. CsF
Which fluoride is the most ionic? A. NaF B. CsF C. MgF2 D. BaF2
C. The carbon to oxygen bond length for the C―OH bond is longer than the carbon to oxygen bond length for the C=O bond.
Which is a correct statement about the bond lengths in ethanoic acid, CH3COOH? A. The carbon to oxygen bond length for the C―OH bond is the same as the carbon to oxygen bond length for the C=O bond. B. The carbon to oxygen bond length for the C―OH bond is shorter than the carbon to oxygen bond length for the C=O bond. C. The carbon to oxygen bond length for the C―OH bond is longer than the carbon to oxygen bond length for the C=O bond. D. The carbon to carbon bond length for the C―CH3 bond is the same as the carbon to oxygen bond length for the C=O bond.
B. Pentane
Which is a non-polar liquid? A. Propan-1-ol B. Pentane C. Propan-2-ol D. Propanone
A. CCl4
Which is a non-polar molecule? A. CCl4 B. HCN C. H2S D. SO2
D. NH2- < NH3 < NH4+
Which is correct when the species NH2-, NH3 and NH4+ are arranged in order of increasing H-N-H bond angle? A. NH3 < NH4+ < NH2- B. NH4+ < NH3 < NH2- C. NH2- < NH4+ < NH3 D. NH2- < NH3 < NH4+
C. Each oxygen atom is covalently bonded to two hydrogen atoms and attracted to two other hydrogen atoms by hydrogen bonding.
Which is the best description of the bonding present in ice? A. Each oxygen atom is covalently bonded to four hydrogen atoms. B. Each oxygen atom is attracted to four hydrogen atoms by hydrogen bonding. C. Each oxygen atom is covalently bonded to two hydrogen atoms and attracted to two other hydrogen atoms by hydrogen bonding. D. Each oxygen atom is covalently bonded to two hydrogen atoms and attracted to two other hydrogen atoms by dative bonding.
C. Fe(OH)3
Which is the correct formula for iron(III) hydroxide? A. Fe2(OH)3 B. Fe3OH C. Fe(OH)3 D. Fe3(OH)2
A. C2H6 > C2H4 > C2H2
Which is the correct order when the molecules ethane, ethene and ethyne are arranged in order of decreasing carbon to carbon bond length? A. C2H6 > C2H4 > C2H2 B. C2H2 > C2H4 > C2H6 C. C2H6 > C2H2 > C2H4 D C2H2 > C2H6 > C2H4
A. HCN
Which molecule has a linear shape? A. HCN B. SO2 C. H2S D. SiO2
D. NH4+
Which molecule or ion contains a dative (coordinate) covalent bond? A. CO2 B. C2H4 C. OH- D. NH4+
B. I and III only
Which molecules or ion contain a bond angle less than 109 degrees? I. NH3 II. CCl4 III. H3O+ A. I and II only B. I and III only C. II and III only D. I, II and III
d
Which of the following is the most likely formula of the compound formed when element X (in group 13) and element Y (from group 16) react together? a) XY b) X3Y2 c) XY2 d) X2Y3
c) I, II and III
Which of the following statements best describe the structure of the sodium chloride, NaCl, lattice? I. Each sodium ion is surrounded by six chloride ions. II. The oppositely charged ions are held together by electrostatic forces of attraction. III. The lattice forms a cubic structure. a) I and II only b) II and III only c) I, II and III d) I and III only
d) Covalent bonding occurs between non-metal elements that tend to have small differences in electronegativity
Which of the following statements is correct? a) Covalent bonding occurs between metal elements that tend to have small differences in electronegativity b) Covalent bonding occurs between metal and non-metal elements that tend to have small differences in electronegativity c) Covalent bonding occurs between metal and non-metal elements that tend to have large differences in electronegativity d) Covalent bonding occurs between non-metal elements that tend to have small differences in electronegativity
b) A carbon-carbon double bond involves the sharing of four valence electrons between the two carbon atoms.
Which of the statements below concerning multiple bonding between carbon atoms is correct? a) Single bonds are shorter than double bonds. b) A carbon-carbon double bond involves the sharing of four valence electrons between the two carbon atoms. c) A triple bond is weaker than a double or single bond. d) A double bond involves the sharing of two electrons between the atoms.
B. The elements are non-metals.
Which statement is correct about twoelements whose atoms form a covalent bond with each other? A. The elements are metals. B. The elements are non-metals. C. The elements have very low electronegativity values. D. The elements have very different electronegativity values.
D. They have high melting and boiling points.
Which statement is true for most ionic compounds? A. They contain elements of similar electronegativity. B. They conduct electricity in the solid state. C. They are coloured. D. They have high melting and boiling points.
B. NaNO3
Which substance contains both ionic and covalent bonds? A. HCN B. NaNO3 C. MgO D. HCOOH
C. H2(g)
Which substance has the lowest electrical conductivity? A. Cu(s) B. Hg(l) C. H2(g) D. LiOH(aq)
C. CH3CH2OH
Which substance is most soluble in water (in mol dm-3) at 298 K? A. CH3CH3 B. CH3OCH3 C. CH3CH2OH D. CH3CH2CH2CH2OH
D. HF contains hydrogen bonding whereas HCl does not.
Why is the boiling point of HCl lower than the boiling point of HF? A. The H-Cl bond is weaker than the H-F bond. B. Van der Waals' forces are weaker in HCl than in HF. C. HF is polar whereas HCl is non-polar. D. HF contains hydrogen bonding whereas HCl does not.
B. PH3 is not hydrogen bonded whereas NH3 is hydrogen bonded.
Why is the boiling point of PH3 lower than that of NH3? A. PH3 is non-polar whereas NH3 is polar. B. PH3 is not hydrogen bonded whereas NH3 is hydrogen bonded. C. Van der Waals' forces are weaker in PH3 than in NH3. D. The molar mass of PH3 is greater than that of NH3.
linear shape
what shape is this?
pyramidal planar
what shape is this?
pyramidal triangular
what shape is this?
