5.0 minutes. The temperature rose from

Transcription

1 QUESTION 1 The table belw describes features cmmn t a slutin calrimeter and a bmb calrimeter as well as differences. Features f Bth the Slutin and Bmb alrimeters W X Features f the Bmb alrimeter Only Y Z The letters W, X, Y and Z respectively culd represent: B D Insulated vessel, calibratin heater, stirring rd, thermmeter. alibratin heater, stirring rd, thermmeter, ignitin wire. Stirring rd, thermmeter, ignitin wire, pressurised cmpartment. Thermmeter, ignitin wire, pressurised cmpartment, stirring rd. QUESTION 2 student cnnected a slutin calrimeter t an electric circuit and supplied and maintained a current f 185 m fr a perid f t The calibratin cnstant fr this calrimeter is 6.00V 5.0 minutes. The temperature rse frm B D Jg Jg Jg Jg Slutin The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 1

2 QUESTION 3 grup f students use a bmb calrimeter t determine the energy cntent f a biscuit. Which f the fllwing is an example f a randm errr that culd ccur during the experiment? B D The students used anther grup s calibratin factr fr all their calculatins. The markings n the thermmeter had wrn ff, s the lab technician had re-labelled it. Unfrtunately, this had been dne incrrectly. The mechanism in the electrnic balance was bent, and the reading was always greater than it shuld have been g The stirring rd f the calrimeter was brken, and s the water bath was nt stirred thrughut the experiment. QUESTION 4 student knws that ne gram f apple yields abut 22.5 kj f energy. She weighs a small piece f apple and burns it in a bmb calrimeter. The bmb calrimeter cntains 100 ml f water and has a calibratin factr f. The small piece f apple has a mass f. She shuld expect the temperature f the water t rise by apprximately: 0.12 g 450J 1 B D Slutin The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 2

3 QUESTION 5 When barium hydrxide and ammnium cyanate are mixed, the fllwing reactin ccurs: Ba( OH) 2.8H 2O( s) 2NH 4NO( s) Ba( NO) 2( s) 2NH 3( aq) 10H 2O( l) H 75kJ / ml f hydrated barium hydrxide (mlar mass g / ml ) are mixed with f ammnium cyanate (mlar mass 60 g / ml ) in a calrimeter. The calrimeter cnstant is g 150 J /. If the initial temperature is 20, the final temperature will be 6.0 g B D Slutin QUESTION g sample f black cal was burnt in a calrimeter. The 300 ml f water in the calrimeter rse in temperature frm t alculate the heat f cmbustin f the cal sample. Slutin The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 3

4 QUESTION 7 student determined the heat f cmbustin f ctane using the apparatus illustrated. She measured the mass f ctane burnt and the rise in temperature f the water in the calrimeter. Frm this data she calculated the heat f cmbustin. (a) Write an equatin fr the cmplete cmbustin f ne mle f ctane. (b) State three ways in which the student culd have imprved this experiment and btained a mre accurate value fr the mlar heat f cmbustin f ctane. The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 4

5 (c) Hw many kiljules are absrbed in raising the temperature f the water frm t 20.9? 17.0 (d) Use these results t calculate the heating energy which wuld have been evlved if ne mle f ctane had been burnt. The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 5

6 QUESTION 8 chemist wishes t determine the heat f cmbustin f a sample f cmpletely dry bread. He dries a sample f the bread in an ven fr 30 minutes, weighs it, carries ut the series f peratins and measurements shwn in the fllwing diagram. (a) alculate the calibratin factr f the calrimeter plus cntents. (b) alculate the heat f cmbustin f the bread in kj per gram. The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 6

7 (c) It is suggested that the measured heat f cmbustin may be in errr because f the bread sample riginally placed in the calrimeter was nt cmpletely dry. Suggest a simple way f finding ut if a given bread sample was cmpletely dry g (d) 3.30 g bread sample had nt been cmpletely dry, what errr wuld this have If the intrduced int the measured heat f cmbustin? Give a reasn fr yur answer. (e) akes and carrts are bth rich in carbhydrates. Why is the carbhydrate in cake bserved t be much mre fattening than the same mass f carbhydrate in carrt? (f) sample f crnflakes was cmbusted in a bmb calrimeter in rder t determine the energy cntent f fd. Wuld these results give a true indicatin f the energy cntent f the fd? Wuld these results give the true indicatin f energy available t the bdy? Give a reasn fr yur answer. The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 7

8 QUESTION 9 In an experiment t determine the energy cntent f naphthlane, was used. Initially a cnstant current f secnds. The ptential difference was t g 10 H was passed thrugh the electric heater fr 4.95V. The temperature increased frm sample f naphthalene was then burnt in the bmb calrimeter and the temperature increased frm t alculate the heat f cmbustin fr naphthalene. Slutin., a bmb calrimeter The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 8

9 QUESTION 1 QUESTION 2 QUESTION 3 QUESTION 4 QUESTION 5 nswer is nswer is nswer is D nswer is D nswer is B QUESTION 6 QUESTION 7 (a) (b) (c) The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 9

10 (d) QUESTION 8 (a) (b) (c) (d) (e) The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 10

11 (f) QUESTION 9 The Schl Fr Excellence 2017 Unit 3 & 4 hemistry alrimetry Wrksheet 1 Page 11