11.2. The chemical properties of the halogen elements and the hydrogen halides
A subsection of Chemistry, 9701, through 11. Group 17
Listing 10 of 102 questions
Carbon and silicon are elements in Group14. C60 and diamond are allotropes of carbon. Describe the lattice structure of solid C60. C60 sublimes (turns directly from solid to gas) at about 800 K. Diamond also sublimes but only above 3800 K. Explain why C60 and diamond sublime at such different temperatures. C60 forms hydrocarbons with similar chemical properties to those of alkenes. One such hydrocarbon is C60H18. State what is meant by the term hydrocarbon. Describe a test to indicate the presence of double bonds between carbon atoms in C60H18. Give the result of the test. test result  0.144 g of C60 was placed in a 100 cm3 container of hydrogen gas at 20 °C and 1.00×105Pa. The container was heated to make the C60 and hydrogen gas react. The reaction occurred as shown in the equation. C60+ xH2C60H2xAfter the reaction, the container was allowed to cool to 20 °C. The pressure decreased to 2.21×104 Pa. All of the C60 had reacted. Name the type of reaction that occurred. Calculate the amount, in moles, of C60 that reacted.  amount of C60 = mol Calculate the amount, in moles, of hydrogen gas that reacted with the C60.  amount of hydrogen gas = mol Use your answers from and to deduce the molecular formula of the hydrocarbon, C60H2x. If you were unable to calculate the amount of hydrogen gas, assume that 0.00240 mol of hydrogen gas reacted. This is not the correct value for the amount of hydrogen gas that reacted.  molecular formula = Silicon shows the same kind of bonding and structure as diamond. State the type of bonding and structure shown by silicon. When silicon reacts with magnesium, Mg2Si forms. Mg2Si is thought to contain the Si4– ion. State the full electronic configuration of the Si4– ion. 1s2 Solid Mg2Si reacts with dilute hydrochloricacid to form gaseous SiH4 and a solution of magnesiumchloride. Write an equation to show the reaction of solid Mg2Si with dilute hydrochloricacid. Include state symbols. Predict the shape of the SiH4 molecule. SiH4 reacts spontaneously with oxygen to produce a white solid and a colourless liquid that turns anhydrous copper(sulfate blue. No other products are formed. Write an equation for the reaction of SiH4 with oxygen. State symbols are not required. 
9701_m18_qp_22
THEORY
2018
Paper 2, Variant 2
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Ethene, C2H4, and hydrazine, N2H4, are hydrides of elements which are adjacent in the Periodic Table. Data about ethene and hydrazine are given in the table below. C2H4 N2H4 melting point/°C –169 +2 boiling point/°C –104 +114 solubility in water insoluble high solubility in ethanol high high Ethene and hydrazine have a similar arrangement of atoms but differently shaped molecules. What is the H-C-H bond angle in ethene? Draw a ‘dot-and-cross’ diagram for hydrazine. What is the H-N-H bond angle in hydrazine? The melting and boiling points of hydrazine are much higher than those of ethene. Suggest reasons for these differences in terms of the intermolecular forces each compound possesses. Explain, with the aid of a diagram showing lone pairs of electrons and dipoles, why hydrazine is very soluble in ethanol. Ethene and hydrazine each react with HCl. When ethene is reacted with HCl, C2H5Cl is the only product. Using structural formulae, give an equation for the reaction between ethene and HCl. What type of reaction occurs between HCl and ethene? Explain why there is no further reaction between C2H5Cl and HCl. When aqueous hydrazine is reacted with HCl, a solid compound of formula N2H5Cl may be isolated. When an excess of HCl is used, a second solid, N2H6Cl2, is formed. Suggest what type of reaction occurs between hydrazine and HCl. What feature of the hydrazine molecule enables this reaction to occur? Suggest why one molecule of hydrazine is able to react with one or two molecules of HCl.
9701_s07_qp_2
THEORY
2007
Paper 2, Variant 0
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Describe and explain how the boiling points of the tetrachlorides of the Group IV elements vary down the group. The tetrachlorides are all covalent compounds. Draw a diagram showing the shape of a molecule of silicon tetrachloride, including values for bond angles. The noble gas xenon forms a tetrafluoride, XeF4. Only four of xenon’s outer shell electrons are used in bonding to the fluorine atoms. Draw a dot-and-cross diagram showing how the outer-shell electrons are arranged in XeF4. Predict the shape and the bond angles in XeF4. Describe and explain how the reactions of CCl4 and SiCl4 with water differ. Write an equation for any reaction that occurs. Use [T Many tonnes of lead tetrachloride used to be produced to make the anti-knock petrol additive tetraethyl-lead, Pb(C2H5)4, by the following reaction. PbCl4 + ………… Na + ………… C2H5Cl ⎯⎯→ Pb(C2H5)4 + ………… NaCl Balance this equation and use it to calculate the mass of sodium needed to produce 1.0 kg of tetraethyl-lead.
9701_w06_qp_4
THEORY
2006
Paper 4, Variant 0
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Questions Discovered
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