Jordanhill School Chemistry Department National 5 Unit 1 Homework Exercises

Transcription

1 Jordanhill School Chemistry Department National 5 Unit 1 Homework Exercises Instructions The purpose of this booklet is to help you revise earlier work, to give you practice with past exam questions, and to improve your knowledge and understanding of Higher chemistry. It is therefore important that your homework exercises are your best work. As such, you should follow these instructions: 1. Use your text book and notes to help you with the questions. 2. You will be given 1 week to complete each exercise. This is to give you time to complete the exercise, and to seek help from your teacher if you cannot work out the answer to a question. Do not leave blanks! Seek help! 3. Please look after this booklet as you will have to return it at the end of the course. If you follow these instructions, you will continue to be successful at chemistry. Do not write on this book, all exercises should be completed in your homework jotter

2 Volume of hydrogen (cm 3 ) Concentration (mol l -1 ) Int Exercise 1- Reaction Rates Int The graph below shows a variation of concentration of a reactant with time as a reaction proceeds During the first 20s, the average reaction rate, in mol l -1 s -1, is A B C D Int Magnesium was reacted with dilute hydrochloric acid under different conditions. In each experiment an excess of magnesium was added. 100 cm 3 2 mol l -1 hydrochloric acid at 20 C Time (s) Reaction 1 Reaction cm 3 1 mol l -1 hydrochloric acid at 20 C 3. The table shows the times taken for 0.5g of magnesium to react completely with acid under different conditions. Acid concentration (mol l -1 ) Temperature ( C) Reaction time (s) The time for 0.5g of magnesium to react completely with 0.2 mol l -1 acid ad 25 C will be A less than 10s B between 10s and 20s C between 20s and 60s D more than 80s Int Graph P shows the volume of hydrogen gas collected when 1.0g of magnesium ribbon reacts with excess 2 mol l -1 hydrochloric acid P Q magnesium powder Which line in the table correctly describes Reaction 2 when compared to Reaction 1? Rate of reaction A faster less B faster the same C slower less D slower the same magnesium powder Volume of gas produced Time (s) Which of the following samples of magnesium, when reacted with excess 2 mol l -1 hydrochloric acid would produce graph Q. A 0.5g of magnesium ribbon B 0.5g of magnesium powder C 1.0g of magnesium powder D 2.0g of magnesium ribbon

3 Int Hydrochloric acid is a strong acid. The table shows the ph values of some hydrochloric acid solutions. Concentration (mol l -1 ) ph (a) Predict the concentration of hydrochloric acid solution with a ph of 5. (1) (b) Describe the experiment which you could carry out to compare the rate of reaction of hydrochloric acid and ethanoic acid with magnesium. (2) Int Human blood contains Fe 3+ ions. To find the concentration of Fe 3+ in blood, the Fe 3+ ions are first converted into Fe 2+ ions. (a) Fe 2+ ions are then reacted to form a purple compound. When the solution is placed in a beam of light only some of the light is transmitted. These results show the percentage of light transmitted for a series of solutions of known Fe 2+ concentration. Concentration Fe 2+ (mg l -1 ) % Transmittance (i) Plot the results as a line graph (3) (ii) Using your graph, estimate the concentration of Fe 2+ ions present in a solution with a transmittance of 36%. SG C 2002/ Int (1) 7. The rate of reaction between zinc and dilute hydrochloric acid can be followed by measuring the volume of gas given off during the reaction. (a) Copy, complete and label the diagram to show how you would collect the gas given off. (2) zinc pieces dilute hydrochloric acid

4 7. (continued) (b) The results for the reaction are shown below. Time (seconds) Volume of gas (cm 3 ) Predict the volume of gas which would have been given off after 60 seconds. (1) (c) Calculate the average rate at which gas is given off during the first 40 seconds of the reaction. (2) (d) Why would increasing the concentration of the acid increase the rate of reaction? (1) SG C A student added magnesium ribbon to an excess of dilute sulphuric acid and measured the volume of hydrogen gas produced. The reaction stopped when all the magnesium was used up. Time /s Volume of hydrogen gas /cm (a) State the test for hydrogen gas. (b) Draw a line graph of the results use appropriate scales to fit most of the graph paper (1) (3) (c) Using your graph, predict the volume of hydrogen gas produced during the first 30 seconds (1) (d) The student repeated the experiment using a higher concentration of acid. The same volume of acid and the same mass of magnesium ribbon were used. What volume of hydrogen gas would have been produced after 60 seconds? (1)

5 Int Exercise 2- Atoms Int Which of the following elements has similar chemical properties to argon? 5. The table shows information about some atoms 2. A Fluorine B Krypton C Potassium D Zinc solid Which of the following would not be evidence of a chemical reaction when a solid is added to the solution? A A colour change B A gas being given off C The temperature rising D The solid disappearing solution Atom Atomic number Mass number W X Y Z Which two atoms are isotopes of the same element? A W and X B X and Y C W and Y D Y and Z Int Which of the following elements exists as a noble gas? A Nitrogen B Fluorine C Oxygen D Neon Int Which of the following elements is an alkali metal? A Aluminium B Calcium C Copper D Sodium 4. Which of the following is the electron arrangement of a halogen atom? A 2,5 B 2,6 C 2,7 D 2,8 Int An atom has atomic number 17 and mass number 35. The number of neutrons in the atom is A 17 B 18 C 35 D 52 Int Which line in the table correctly describes a proton? Mass Charge Location A negligible 0 outside nucleus B negligible -1 outside nucleus C 1 +1 in nucleus D 1 0 in nucleus

6 Int The most common isotope of potassium is. 39 K K 19 (a) Copy and complete the table to show the number of particles in an atom of. Type of particle Number of particles Proton Neutron Electron (b) How do isotopes of potassium differ from each other? (1) (1) 10. Strontium compounds have many uses. Int (a) Strontium nitrate is used in warning flares. What colour flame will strontium nitrate give? (1) (you may wish to use the data booklet to help you.) (b) Strontium chloride hexahydrate can be used in toothpaste for sensitive teeth as it plugs the holes in the tooth enamel. This is possible because strontium has similar chemical properties to calcium. Why does strontium have similar chemical properties to calcium? (1) 11. Electrons are arranged in energy levels. Int Complete the diagram to show how the electrons are arranged in an atom of sodium (1) (You may wish to use page 6 of the data booklet to help you.) = Nucleus X = Electron

7 Electronegativity 12. There are three different types of neon atom. SG C 2009 Type of atom Number of protons Number of neutrons Ne Ne Ne (a) Complete the table to show the number of protons and neutrons in each atom. (1) (b) What term is used to describe the different types of neon atom? (1) (c) A natural sample of neon has an average atomic mass of What is the mass number of the most common type of atom in the sample of neon? (1) Int Electronegativity is the measure of attraction that an atom has for the bonded electrons. The chart shows the electronegativity values for some elements in the periodic table. Atomic number (a) Describe what happens to the electronegativity values going across a period in the periodic table. (1) (b) Give a value for the electronegativity of the element calcium, atomic number 20. (1)

8 Int Exercise 3- Ions and Bonding Int In a hydrogen fluoride molecule, the atoms share electrons in order to achieve the same electron arrangements as the atoms in group A 0 B 1 C 2 D 7 Int The table below show information about an ion. Particle Number protons 19 neutrons 20 electrons 18 The charge on the ion is A 1+ B 1- C 2+ D 2- Int Which substance does not exist as diatomic molecules? A Nitrogen B Oxygen C Fluorine D Neon 5. During electrolysis of silver(i) nitrate solution, silver ions, Ag + (aq), A gain electrons at the negative electrode B lose electrons at the negative electrode C gain electrons at the positive electrode D lose electrons at the positive electrode. A B C Int Which of the following diagrams represents a compound made up of diatomic molecules? 4. Which one of the following particles contains a different number of electrons from the others? (You may wish to use page 6 of the data booklet to help you.) D A Cl - B S 2- C Ar D Na +

9 SG C The grid shows some ions. A B C Al 3+ Cl - Li + D E F H + Br - OH - (a) Identify the ion with the same electron arrangement as a helium atom. (1) You may wish to use the data booklet to help you. (b) Identify the two ions which combine to form an insoluble compound. (1) You may wish to use the data booklet to help you. SG C 2004* 8. The table contains some information about some substances Substance Melting point/ C Boiling point/ C Conducts as a solid a liquid A no yes B no no C yes yes D no no E no yes F yes yes (a) Identify the two ionic compounds. (1) (b) Identify the substance which exists as a covalent network. (1) (c) Identify the substances which would be liquid at 1500 C (2) SG C Copy and complete the table to show the number of each type of particle in Cl- Type of particle Proton Neutron Electron Number of particles (1)

10 SG C In a hydrogen molecule the atoms share two electrons in a covalent bond. + = Nucleus + + = Electron (a) Explain how the covalent bond holds the two hydrogen atoms together. (1) (b) The hydrogen molecule can be represented more simply as H H Showing all outer electrons, draw a similar diagram to represent a molecule of ammonia, NH3. (1) Int / N The properties of a substance depend on its type of bonding and structure. There are four types of bonding and structure. A B C D Discreet covalent molecular Covalent network Ionic lattice Metallic lattice (a) Complete the table to match up each type of bonding with its properties Bonding and structure type Properties Do not conduct electricity and have high melting points Have high melting points and conduct electricity when liquid but not when solid Conduct electricity when solid and have a wide range of melting points Do not conduct electricity and have low melting points (2) (b) Graphene is a substance made of a single layer of carbon atoms. Graphene can conduct electricity. Suggest what this means about some of the electrons in graphene. (1)

11 11. (Continued) (c) A section of a covalent network compound is shown below. Write the formula for this covalent network compound. (1) SG C Nitrogen trifluoride, NF3, is used in the manufacturing of plasma screens. (a) Draw a diagram showing all outer electrons in a molecule of nitrogen trifluoride. (1) (b) The atoms in nitrogen trifluoride are held together by covalent bonds. Copy the sentence with the correct words to give information about covalent bonds (1) SG C A student investigated how the concentration of sodium chloride in water affected the freezing point. (a) What type of bond is broken in sodium chloride when it is dissolved in water? (1) (b) The table shows information about the freezing point of different sodium chloride solutions. Concentration of sodium chloride solution (mol/l) Freezing point ( o C) Describe the relationship between the concentration and freezing point. (1) (c) Predict the freezing point of a 0.55 mol/l sodium chloride solution. (1)

12 SG C A student set up the following experiment to electrolyse cobalt chloride solution. (a) The formula for cobalt chloride is CoCl2. What is the charge on the cobalt ion in CoCl2? (1) (b) Describe what would be seen at the positive electrode. (1) You may wish to use your data booklet to help you. 15. The grid shows the formulae of some oxides. SG C 2011 A B C ZnO NO2 K2O D E F CuO Fe2O3 CO Identify the two oxides which are covalent. (1) Int A hydrogen fluoride molecule can be represented as: H X F Showing all outer electrons draw a similar diagram to represent a molecule of water, H2O (2)

13 Exercise 4- Formula and Shapes of Molecules Int The charge on the iron ion in Fe2(SO4)3 is A 2 + B 3 + C 2 - D 3 - Int The formula for magnesium sulfate is A MgS B MgSO3 C MgSO4 D MgS2O3 Int A metal X reacts with oxygen to form an oxide, X2O3. During the reaction each atom of metal X A gains two electrons B gains three electrons C loses two electrons D loses three electrons Int Which of the following compounds contains only two elements? A Magnesium hydroxide B Magnesium phosphate C Magnesium sulfite D Magnesium nitride 7. A substance, X, has a melting point of 996 C and a boiling point of 1704 C. It only conducts electricity when molten or dissolved in water. The structure of X is likely to be A ionic B metallic C covalent network D covalent molecular Int The shapes and names of some molecules are shown below. 4. The formula for potassium sulfate is A P2SO3 B K2SO4 C P2SO4 D K2S Int When hydrogen chloride gas is dissolved in water a solution containing hydrogen ions and chloride ions is formed. Which equation correctly shows the state symbols for this change? A HCl(g) + H2O(l) H + (aq) + Cl - (aq) B HCl(l) + H2O(aq) H + (l) + Cl - (l) C HCl(aq) + H2O(l) H + (aq) + Cl - (aq) D HCl(g) + H2O(l) H + (l) + Cl - (l) tetrahedral pyramidal bent linear Phosphine is a compound of phosphorus and hydrogen. The shape of the molecule of phosphine is likely to be A tetrahedral B pyramidal C bent D linear Int What is the name of the compound with the formula VO2? A Vanadium(V) oxide B Vanadium(IV) oxide C Vanadium(III) oxide D Vanadium(II) oxide

14 10. Two tests were carried out for compound X. Int The following results were obtained. Test Result 1 Limewater turns cloudy 2 Flame turns blue/green Which of the following could be compound X? (You may wish to use page six of the data booklet to help you) A Barium carbonate B Copper carbonate C Copper sulfate D Sodium sulfate 11. Rust contains iron(iii) oxide. Int * (a) Write the formula for iron(iii) oxide. (1) (b) What type of bonding occurs in iron(iii) oxide? (1) Int Chlorofluorocarbons (CFCs) are a family of compounds which are highly effective as refrigerants and aerosol propellants. However, they are now known to damage the ozone layer. One example of a CFC molecule is shown. What term is used to describe the shape of this molecule? (1)

15 Int * 13. Information on some two-element molecules is shown in the table. Name Hydrogen fluoride Water Ammonia Methane Formula HF H2O NH3 CH4 (a) Draw and name the shapes of each of the molecules on the table. (4) (b) The hydrogen fluoride molecule can be represented as: H X F Showing all outer electrons, draw a similar diagram to represent a molecule of methane, CH4 (2) Int Glass is made up from the chemical silica, SiO2, which is covalently bonded and has a melting point of 1700 C (a) What does the melting point of silica suggest about its structure? (1) (b) Antimony(III) oxide is added to reduce any bubbles that may appear during the manufacturing process. Write the chemical formula for antimony(iii) oxide (1) (c) In the manufacture of glass, other chemicals can be added to alter the properties of the glass. The element boron can be added to the glass to make oven proof dishes. (i) Information about an atom of boron is given in the table below. Particle Number proton 5 electron 5 neutron 6

16 Volume of nitrogen produced (litres) 14. (Continued) Use this information to complete the nuclide notation for this atom of boron. B (1) (ii) Atoms of boron exist which have the same number of protons but a different number of neutrons from that shown in the table. What name can be used to describe the different atoms of boron? (1) Int Rapid inflation of airbags in cars is caused by the production of nitrogen gas. The graph gives information on the volume of gas produced over 30 microseconds Time (microseconds) (a) (i) Calculate the average rate of reaction between 2 and 10 microseconds. (1) (ii) At what time has half of the final volume of nitrogen gas been produced? (1) (b) In some types of airbags, electrical energy causes sodium azide, NaN3, to decompose producing sodium metal and nitrogen gas. Write a formula equation for this (1) (c) Potassium nitrate is also present in the airbag to remove the sodium metal by converting it into sodium oxide. Why is it necessary to remove the sodium metal? (1)

17 Int Exercise 5- The mole 1. The gram formula mass of sodium carbonate is 106g. How many moles are present in 5.3g of sodium carbonate? A 0.05 B 0.5 C 2 D 20 Int What is the relative formula mass of ammonium sulfate, (NH4)2SO4? A 70 B 118 C 132 D 228 Int The formula mass of ammonium carbonate, (NH4)2CO3 is? A 52 B 64 C 96 D 110 Int What is the correct formula for aluminium sulfate? A AlSO4 B Al(SO4)3 C Al2(SO4)3 D Al3(SO4)2 5. Glucose has the molecule formula C6H12O6. How many moles are contained in 18g of glucose? A 0.01 B 0.1 C 1 D moles of gas has a mass of 12.8g. Which of the following could be the molecular formula for the gas? A SO2 B CO C CO2 D NH3 Int How many moles are present in 1.7g of ammonia, NH3? A 0.1 B 1.0 C 1.7 D 17 Int xal(s) + ybr2(l) zalbr3(s) The equation will be balanced when A x = 1, y = 2, z = 1 B x = 2, y = 3, z = 2 C x = 3, y = 2, z = 3 D x = 4, y = 3, z = 4 Int NH3 + xo2 4NO + yh2o The equation will be balanced when A x = 5, y = 6 B x = 5, y = 10 C x = 3, y = 6 D x = 3, y = Which of the following substances has the smallest gram formula mass? A CO B CO2 C N2 D CH4

18 Int The equation below shows the breakdown of glyceryl tristearate to form glycerol and stearic acid. C57H110O6 + 3H2O C3H8O3 + 3C18H36O2 glyceryl tristearate water glycerol stearic acid GFM = 890g Calculate the mass of stearic acid produced from 8.9g of glycerol tristearate. (3) Int Ammonia can be used to make the fertiliser, ammonium phosphate. 3NH3 + H3PO4 (NH4)3PO4 Calculate the mass of ammonium phosphate that would be produced from 510g of ammonia. (3) Int Hydrogen peroxide is a useful bleaching agent and is contained in many hair dyes. Over time, the hair dye becomes less effective as the hydrogen peroxide decomposes forming water and oxygen. The equation for the decomposition of hydrogen peroxide is: H2O2(aq) O2(g) + H2O(l) (a) Balance this equation (b) State the test for oxygen gas (1) (1) (c) When 34g of hydrogen peroxide decomposes, 12 litres of oxygen is produced. Calculate the volume of oxygen produced when 1.7g of hydrogen peroxide decomposes (2) 14. Ammonium sulfate is a commonly used fertiliser. It can be produced by the reaction between ammonium carbonate and calcium sulfate. (NH4)2CO3(aq) + CaSO4(aq) (NH4)2SO4(aq) + CaCO3(s) What mass of ammonium carbonate, (NH4)2CO3, would be needed to make 13.2kg of ammonium sulfate (NH4)2SO4? (3)

19 Int Gold is a very soft metal. In order to make it harder, goldsmiths mix it with silver. The quality of gold is indicated in carats. (a) The graph shows information about the quality of the gold. (i) What is the percentage of silver in an 18 carat gold ring? (1) (ii) Calculate the mass of silver in an 18 carat gold ring weighing 6g. (1) (b) Silver tarnishes in air forming black silver sulfide, Ag2S. The equation for the reaction is: 4Ag + 2H2S + O2 2Ag2S + 2H2O What mass of silver sulfide would be formed from 1.08g of silver? (3) Int Iron is produced from iron ore in a Blast Furnace. The equation is shown: Fe2O3(s) + CO(g) Fe(l) + CO2(g) (a) Balance this equation. (b) From the balanced equation below, calculate the mass of carbon monoxide produced when 1200kg of carbon reacts. (1) (3) CO2(g) + C(s) 2CO(g)

20 Exercise 6- ph & Neutralisation Int Which oxide, when shaken with water, would leave the ph unchanged? A Calcium oxide B Carbon dioxide C Sulfur dioxide D Zinc oxide Int An acidic solution contains A Only hydrogen ions B Equal numbers of hydrogen and hydroxide ions C More hydrogen ions than hydroxide ions D More hydroxide ions than hydrogen ions Int Which of the following statements describes the concentrations of H + (aq) and OH - (aq) ions in pure water? A The concentrations of H + (aq) and OH - (aq) ions are equal. B The concentrations of H + (aq) and OH - (aq) ions are zero. C The concentration of H + (aq) ions is greater than the concentration of OH - (aq) ions. D The concentration of OH - (aq) ions is greater than the concentration of H + (aq) ions. 4. Which of the following sodium chloride solutions would contain the most dissolved solute? A 100cm 3 of 4 mol l -1 solution B 200cm 3 of 3 mol l -1 solution C 300cm 3 of 1 mol l -1 solution D 400cm 3 of 0.5 mol l -1 solution Int mol of potassium hydroxide was dissolved in water and the solution made up to 500cm 3. What was the concentration, in mol l -1, of the solution which was formed? A B C 0.5 D Identify the spectator ions in the following: Pb 2+ (aq) + 2NO3 - (aq) + 2Na + (aq) + 2I - (aq) Pb 2+ (I - )2(s) + 2Na + (aq) + 2NO3 - (aq) A Na + (aq) and NO3 - (aq) B Na + (aq) and I - (aq) C Pb 2+ (aq) and NO3 - (aq) D Pb 2+ (aq) and I - (aq) Int Which of the following oxides, when shaken with water, would leave the ph unchanged? (you may wish to use page 8 of the data booklet to help you.) A Carbon dioxide B Copper oxide C Sodium oxide D Sulfur dioxide 8. Which of the following compounds is a base? A Magnesium carbonate B Magnesium chloride C Magnesium nitrate D Magnesium sulfate Int Which of the following increases when hydrochloric acid is diluted with water? A Rate of reaction with magnesium B Concentration of H + ions C Electrical conductivity D ph

21 Int When 100cm 3 of a 1 mol l -1 solution of sodium sulfate was evaporated to dryness, 14.2g of solid was obtained. To obtain 14.2g of solid from a 2mol l -1 solution of sodium sulfate the volume of the solution needed would be A 20cm 3 B 50cm 3 C 100cm 3 D 200cm In which of the following test tubes will a gas be produced? A B C D Int mole of sodium chloride can be used to prepare A 250cm 3 of a 0.4 mol l -1 solution B 250cm 3 of a 4 mol l -1 solution C 200cm 3 of a 0.5 mol l -1 solution D 200cm 3 of a 1 mol l -1 solution Int In a neutralisation reaction between an acid and an alkali, the ph A of the acid increases B of the acid is unchanged C of the alkali increases D of the alkali is unchanged 15. An alkaline solution contains A Only hydrogen ions B More hydrogen ions than hydroxide ions C More hydroxide ions than hydrogen ions D Equal numbers of hydrogen ions and hydroxide ions Int Which of the following pairs of chemicals react to produce a gas that turns lime water milky? A Calcium carbonate and dilute hydrochloric acid B Copper oxide and dilute sulfuric acid C Copper and dilute hydrochloric acid D Magnesium and dilute sulphuric acid Int Which of the following oxides will dissolve in water to produce an alkaline solution? (You may wish to use page 8 of the data booklet) A Carbon dioxide B Copper(II) oxide C Potassium oxide D Nitrogen dioxide 17. Which line in the table describes what happens to a dilute solution of hydrochloric acid when water is added to it? ph H + (aq) concentration A increases increases B increases decreases C decreases increases D decreases decreases

22 Int Fizzy drinks contain acids. These acids can attack the compound calcium hydroxyapatite which is found in tooth enamel. The equation for the reaction is: Ca10(PO4)6(OH)2(s) + 8H + (aq) 6CaHPO4(s) + 4Ca 2+ (aq) + 2H2O Calcium hydroxyapatite What will happen to the ph as the tooth enamel is attacked by the acids? (1) Int A student carried out the following experiment. (a) During the reaction a solid was formed. Name the type of chemical reaction taking place (1) (b) The equation for the reaction is Ba 2+ (aq) + 2Cl - (aq) + 2Na + (aq) + SO4 2- (aq) Ba 2+ SO4 2- (s) + 2Cl - (aq) + 2Na + (aq) (i) Rewrite the equation showing only the ions which react (1) (ii) What term is used to describe the ions which do not react? (1)

23 Nat Sodium carbonate solution can be added to the water in swimming pools to neutralise the acidic effects of chlorine. A student carried out a titration experiment to determine the concentration of a sodium carbonate solution (a) Using the results in the table, calculate the average volume, in cm 3, of hydrochloric acid required to neutralise the sodium carbonate solution. (1) (b) The equation for the reaction is 2HCl + Na2CO3 2NaCl + CO2 + H2O Using your answer from part (a) calculate the concentration, in mol l -1, of the sodium carbonate solution. Show your working clearly. (3) SG C The salt copper(ii) nitrate can be produced as shown. X + 2HNO3 Cu(NO3)2 + CO2 +H2O Name substance X (1)