11.1 Measurement & Data HW A 1. The table shows data from five trials of two separate experiments. Which set of values is more precise? Trial 1 2 1.48 3 1.40 4 1.27 5 1.38 Experiment 1 2 1.34 1.37 1.22 1.58 1.18 1.44 2. A series of experiments was carried out to determine the value for a particular quantity. The results are shown on the table. The literature value of this quantity is 47.0 J. Which experiment produced the most accurate value? Experiment Value/J 1 2 3 44.2 4 45.276 48 49.57 3. State the number of significant figures for each of the following numbers: a. 2.78 3 b. 0.057 c. 0.003480 5 d. 3.95 x 104 3 e. 80.00 4 3 4. Round each of the following numbers to three significant figures: a. 6.7863 b. 0.000079835 c. 0.00499931 d. 8.2457 x 105 e. 1.78339 x 10-3
5. A 37.93 g sample of zinc displaces water in a graduated cylinder from a level of 23.37 m- to 28.69 m -. Find the density of zinc, expressing the answer with the appropriate number of significant figures. 6. What is the pH of an aqueous solution when the concentration of hydrogen ion is 5.0 x 10-4 M? 7. What is the [H+] in a solution with a pH of 4.556? 8. Two separate experimental methods were used to determine the value of a particular experimental quantity. Each experiment was repeated five times. The values obtained from these experiments are shown on the table. Experiment 1 Trial Value 1 49.7 2 53.2 3 51.5 4 52.3 5 49.2 51.0 The literature value for this quantity is 50.9. 2 Value 50.6 51.2 51.1 50.8 a. Explain which set of experimental values is more precise. b. Work out a mean value for each experiment and use this to explain which set of data is more accurate.