Create Presentation
Download Presentation

Download

Download Presentation

What is the density of a solid that has a mass of 60.27 g and a volume of 711 mL?

158 Views
Download Presentation

Download Presentation
## What is the density of a solid that has a mass of 60.27 g and a volume of 711 mL?

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -

**What is the density of a solid that has a mass**of 60.27 g and a volume of 711 mL? D = M/V = 0.084767932 g/mL How do we know how to express (where to round off) this answer?**Significant (Measured) Digits in Calculations**All nonzero digits are significant. Evaluating Zero as a Significant Digit A zero is significant when it is : 1. Between nonzero digits: 205 61.09 2. At the end of a number that includes a decimal point: 0.500 25.160 3.00 20.**A zero is not significant when it is :**1. Before the first nonzero digit. (These zeros are used to locate a decimal point.): 0.0025 0.0108 2. At the end of a number without a decimal point: 1000 590**Practice Problem**• How many significant figures are in each of • these numbers? • a) 4.5 inches e) 25.0 grams • b) 3.025 feet f) 12.20 liters • c) 125.0 meters g) 100,000 people • d) 0.001 mile h) 205 birds 2 3 4 4 1 4 3 1**Rounding Off Numbers**Look at the next digit (after those you want to retain for the proper number of significant digits) If it is 5 or greater → round up. If it is 4 or less → round down.**Practice Problem**• Round off these numbers to the number of • significant figures indicated: • 42.246 (four) • 88.015 (three) • 0.08965 (three) • 0.08965 (two) • e) 225.3 (three) • f) 14.150 (three) 42.25 88.0 0.0897 0.090 225 14.2**Multiplication or Division**Round off your answer to be no more than the fewest number of significant digits.**Practice Problem**• (134 in.)(25 in.) = ? • b) 213 miles • 4.20 hours = ? • c) (2.2)(273) • 760 = ? 3400 in2 Limited to 2 sigs 50.7 mi/hr Limited to 3 sigs .79 Limited to 2 sigs**Addition or Subtraction**Round off the answer to no more than the fewest number of places to the right of the decimal. (i.e greatest level of shared confidence)**Practice Problem**• How many significant figures should the • answer in each of these calculations contain? • (14.0)(5.2) • (.1682)(8.2) • c) (160)(33) • 4 • d) 8.2 + 0.125 2 sigs = 73 2 sigs = 1.4 0.125 8.2 = 8.3 1 sig = 1000 2 sigs - tenths**How many significant figures should the**• answer in each of these calculations contain? • e) 119.1 – 3.44 • f) 94.5 • 1.2 • g) 1200 + 6.34 • h) 1.6 + 23 – 0.005 = 115.7 4 sigs - tenths = 79 2 sigs 2 sigs - hundreds = 1200 2 sigs - singles = 25