Name period Date 1. A student investigated the physical and chemical properties of a sample of an unknown gas and then identified the gas. Which statement represents a conclusion rather than an experimental observation? 1) The gas is colorless. 2) The gas is carbon dioxide. 3) When the gas is bubbled into limewater, the liquid becomes cloudy. 4) When placed in the gas, a flaming splint stops burning. 2. Which condition is necessary for an experiment to yield useful data? 1) Similar results should be obtained when the experiment is repeated 2) Only the expected results should be considered each time the experiment is performed. 3) The hypothesis must be correct 4) The experimental period must be short. 5. A sample of a substance containing only magnesium and chlorine was tested in the laboratory and was found to be composed of 74.5% chlorine by mass. If the total mass of the sample was 190.2 grams, what was the mass of the magnesium? 1) 24.3 g 2) 48.5 g 3) 70.9 g 4) 142 g 6. How many kilojoules are equivalent to 10 Joules? 1) 0.001 kj 2) 0.01 kj 3) 1000 kj 4) 10,000 kj 7. The diagram below represents a section of a buret containing acid used in an acid-base titration. 3. Which diagram represents a graduated cylinder? 1) 2) 3) 4) 4. Which measurement contains three significant figures? 1) 0.05 g 2) 0.050 g 3) 0.056 g 4) 0.0563 g What is the total volume of acid that was used? 1) 1.10 ml 2) 1.30 ml 3) 1.40 ml 4) 1.45 ml
8. Which laboratory glassware is shown in the diagram below? 14. A student determined that the percent of H2O in a hydrate was 39.0%. The percent of H2O in this hydrate is 36.0% according to an accepted chemistry reference. What is the student's percent of error? 1) 9.1% 2) 8.3% 3) 3.0% 4) 11% 1) Florence flask 2) Erlenmeyer flask 3) distilling flask 4) volumetric flask 9. Which mass measurement contains a total of three significant figures? 1) 22.0 g 2) 22.00 g 3) 220 g 4) 2200 g 10. A sample of an element has a mass of 34.261 grams and a volume of 3.8 cubic centimeters. To which number of significant figures should the calculated density of the sample be expressed? 1) 5 2) 2 3) 3 4) 4 11. A laboratory experiment was performed to determine the percent by mass of water in a hydrate. The accepted value is 36.0% water. Which observed value has an error of 5.00%? 1) 31.0% water 2) 36.0% water 3) 37.8% water 4) 41.0% water 12. Which quantity is equivalent to 50 kilojoules? 1) 5000 J 2) 0.05 J 3) 5 10 3 J 4) 5 10 4 J 13. A student measures the mass and volume of a piece of aluminum. The measurements are 25.6 grams and 9.1 cubic centimeters. The. student calculates the density of the aluminum. What is the percent error of the student s calculated density of aluminum? 1) 1% 2) 2% 3) 3% 4) 4% 15. One kilojoule is the same as 1) 0.001 Joule 2) 0.01 Joule 3) 100 Joules 4) 1,000 Joules 16. During a laboratory activity, a student combined two solutions. In the laboratory report, the student wrote A yellow color appeared. The statement represents the student s recorded 1) conclusion 2) observation 3) hypothesis 4) inference 17. What is the quotient of 8.01 grams divided by 3.127 grams, expressed to the correct number of significant figures? 1) 2.6 2) 2.56 3) 2.562 4) 2.5616 18. A student wishes to prepare approximately 100 milliliters of an aqueous solution of 6 M HCl using 12 M HCl. Which procedure is correct? 1) adding 50 ml of 12 M HCl to 50 ml of water while stirring the mixture steadily 2) adding 50 ml of 12 M HCl to 50 ml of water, and then stirring the mixture steadily 3) adding 50 ml of water to 50 ml of 12 M HCl while stirring the mixture steadily 4) adding 50 ml of water to 50 ml of 12 M HCl, and then stirring the mixture steadily
19. Which diagram represents a Beaker? 1) 2) 3) 4) 20. A student found the boiling point of a liquid to be. If the liquid's actual boiling point is, the experimental percent error is equal to 1) 2) 3) 4) Short Response: Please show all work or credit will not be given. Base your answers to questions 21 and 22 on the information below and on your knowledge of chemistry. During a laboratory activity, a student places 25.0 ml of HCl(aq) of unknown concentration into a flask. The student adds four drops of phenolphthalein to the solution in the flask. The solution is titrated with 0.150 M KOH(aq) until the solution appears faint pink. The volume of KOH(aq) added is 18.5 ml. 21. Describe one laboratory safety procedure that should be used if a drop of the KOH(aq) is spilled on the arm of the student. 22. What number of significant figures is used to express the concentration of the KOH(aq)?
23. Base your answer to the following question on the information below. A method used by ancient Egyptians to obtain copper metal from copper(i) sulfide ore was heating the ore in the presence of air. Later, copper was mixed with tin to produce a useful alloy called bronze. Calculate the density of a -gram sample of bronze that has a volume of cubic centimeters. Your response must include a correct numerical setup and the calculated result. 24. A student used a balance and a graduated cylinder to collect the following data: a Calculate the density of the element. Show your work. Include the appropriate number of significant figures and proper units. b If the accepted value is 6.93 grams per milliliter, calculate the percent error. c What error is introduced if the volume of the sample is determined first?
Answer Key Intro 2017-18 1. 2 2. 1 3. 1 4. 4 5. 2 6. 2 7. 4 8. 2 9. 1 10. 2 11. 3 12. 4 13. 4 14. 2 15. 4 16. 2 17. 2 18. 1 19. 1 20. 1 21. The student should immediately place his/her arm under running water to dilute and wash away the KOH(aq). Tell the teacher 22. 3 or three 23. 24. a) Examples: or, or, and accept only to the nearest tenth with a range from 6.7-6.9 Proper Units: g/ml or grams per milliliter b) Range of 1.8-2.0% c) The density would increase because the sample was wet when weighed