1 The mole and Avogadro’s constant

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Oxford Textbook Pages : 20 - 21, 26 - 31

CGP Revision Guide Pages : 20 - 21

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Show Specification Ref : 2.1.3a, 2.1.3e, 2.1.3f

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Question 1 / 5

January 2010 QP – Unit 1 AQA Chemistry A-level_question_2 pmt areas outside the box will not be scanned for marking ammonium sulfate reacts with sodium hydroxide to form ammonia sodium sulfate and water as shown in the equation below nh so s naoh aq nh g na so aq h o l a a g sample of ammonium sulfate reacted completely with cm of a sodium hydroxide solution i calculate the amount in moles of nh so in g of ammonium sulfate a marks a ii hence calculate the amount in moles of sodium hydroxide which reacted a mark iii calculate the concentration in moldm of the sodium hydroxide solution used mark b calculate the percentage atom economy for the production of ammonia in the reaction between ammonium sulfate and sodium hydroxide marks wmp jan chem c ammonia is manufactured by the haber process nh n h calculate the percentage atom economy for the production of ammonia in this process mark d a sample of ammonia gas occupied a volume of m at c and a pressure of kpa the gas constant r jk mol calculate the amount in moles of ammonia in this sample marks extra space e glauber s salt is a form of hydrated sodium sulfate that contains by mass of sodium sulfate hydrated sodium sulfate can be represented by the formula na so xh o where x is an integer calculate the value of x marks extra space pmt areas outside the box will not be scanned for marking turn over wmp jan chem
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Question 2 / 5

June 2010 QP – Unit 1 AQA Chemistry A-level_question_2 the following diagram shows the first ionisation energies of some period elements do not write outside the box first ionisation energy kj mol na mg al si cl a draw a cross on the diagram to show the first ionisation energy of aluminium mark b write an equation to show the process that occurs when the first ionisation energy of aluminium is measured marks c state which of the first second or third ionisations of aluminium would produce an ion with the electron configuration s s p s mark d explain why the value of the first ionisation energy of sulfur is less than the value of the first ionisation energy of phosphorus marks extra space wmp jun chem do not write outside the box e identify the element in period that has the highest first ionisation energy and give its electron configuration element electron configuration marks f state the trend in first ionisation energies in group from beryllium to barium explain your answer in terms of a suitable model of atomic structure trend explanation marks extra space turn over for the next question turn over wmp jun chem do not write outside the box in this question give all your answers to three significant figures magnesium nitrate decomposes on heating to form magnesium oxide nitrogen dioxide and oxygen as shown in the following equation mg no s mgo s no g o g a thermal decomposition of a sample of magnesium nitrate produced g of magnesium oxide a i calculate the amount in moles of mgo in g of magnesium oxide marks a ii calculate the total amount in moles of gas produced from this sample of magnesium nitrate mark b in another experiment a different sample of magnesium nitrate decomposed to produce mol of gas calculate the volume in dm that this gas would occupy at k and pa the gas constant r j k mol marks extra space wmp jun chem
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Question 3 / 5

June 2010 QP – Unit 1 AQA Chemistry A-level_question_3 do not write outside the box in this question give all your answers to three significant figures magnesium nitrate decomposes on heating to form magnesium oxide nitrogen dioxide and oxygen as shown in the following equation mg no s mgo s no g o g a thermal decomposition of a sample of magnesium nitrate produced g of magnesium oxide a i calculate the amount in moles of mgo in g of magnesium oxide marks a ii calculate the total amount in moles of gas produced from this sample of magnesium nitrate mark b in another experiment a different sample of magnesium nitrate decomposed to produce mol of gas calculate the volume in dm that this gas would occupy at k and pa the gas constant r j k mol marks extra space wmp jun chem do not write outside the box c a mol sample of magnesium oxide produced from the decomposition of magnesium nitrate was reacted with hydrochloric acid mgo hcl mgcl h o c i calculate the amount in moles of hcl needed to react completely with the mol sample of magnesium oxide mark c ii this mol sample of magnesium oxide required cm of hydrochloric acid for complete reaction use this information and your answer to part c i to calculate the concentration in mol dm of the hydrochloric acid mark turn over for the next question turn over wmp jun chem do not write outside the box a there are several oxides of nitrogen an oxide of nitrogen contains by mass of nitrogen determine the empirical formula of this oxide marks extra space b give one reason why the oxide no is a pollutant gas mark c the oxide no reacts with oxygen to form nitrogen dioxide write an equation for this reaction mark d explain how no is produced in the engine of a motor vehicle marks e write an equation to show how no is removed from the exhaust gases in motor vehicles using a catalytic converter mark wmp jun chem
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Question 4 / 5

June 2012 QP – Unit 1 AQA Chemistry A-level_question_5 section b answer all questions in the spaces provided do not write outside the box a boron trichloride bcl can be prepared as shown by the following equation b o s c s cl g bcl g co g a sample of boron oxide b o was reacted completely with carbon and chlorine the two gases produced occupied a total volume of cm at a pressure of kpa and a temperature of k calculate the mass of boron oxide that reacted give your answer to significant figures the gas constant r j k mol marks extra space wmp jun chem do not write outside the box b boron trichloride can also be prepared from its elements write an equation for this reaction explain why boron trichloride has a trigonal planar shape with equal bond angles marks extra space c i boron trichloride is easily hydrolysed to form two different acids as shown in the following equation bcl g h o i h bo aq hcl aq calculate the concentration in mol dm of hydrochloric acid produced when g of boron trichloride are added to water to form cm of solution give your answer to significant figures marks extra space c ii boric acid h bo can react with sodium hydroxide to form sodium borate and water write an equation for this reaction mark question continues on the next page turn over wmp jun chem do not write outside the box d boron trichloride can be reduced by using hydrogen to form pure boron bcl g h g b s hcl g calculate the percentage atom economy for the formation of boron in this reaction apart from changing the reaction conditions suggest one way a company producing pure boron could increase its profits from this reaction marks extra space e a different compound of boron and chlorine has a relative molecular mass of and contains of boron by mass calculate the molecular formula of this compound show your working marks extra space copyright aqa and its licensors all rights reserved end of questions wmp jun chem
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Question 5 / 5

June 2015 QP – Unit 1 AQA Chemistry A-level_question_7 section b answer all questions in the spaces provided do not write outside the box a some airbags in cars contain sodium azide nan sodium azide is made by reacting dinitrogen monoxide gas with sodium amide nanh as shown by the equation nanh n o nan naoh nh calculate the mass of sodium amide needed to obtain g of sodium azide assuming there is a yield of sodium azide give your answer to significant figures marks question continues on the next page turn over wmp jun chem do not write outside the box b if a car is involved in a serious collision the sodium azide decomposes to form sodium and nitrogen as shown in the equation nan s na s n g the nitrogen produced then inflates the airbag to a volume of m at a pressure of kpa and temperature of c calculate the minimum mass of sodium azide that must decompose the gas constant r j k mol marks wmp jun chem do not write outside the box c sodium azide is toxic it can be destroyed by reaction with an acidified solution of nitrous acid hno as shown in the equation nan hno hcl n no nacl h o c i a cm volume of the nitrous acid solution was used to destroy completely g of the sodium azide calculate the concentration in mol dm of the nitrous acid used marks c ii nitrous acid decomposes on heating balance the following equation for this reaction hno hno no h o d sodium azide has a high melting point predict the type of bonding in a crystal of sodium azide suggest why its melting point is high mark marks type of bonding reason for high melting point question continues on the next page turn over wmp jun chem
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