Section 1: Chemical Calculations Unit 6: Stoichiometry Section 1: Chemical Calculations

How many jumps does it take? Ladder Method 1 2 3 KILO 1000 Units Meters Liters Grams CENTI 0.01 Unit MILLI 0.001 Unit How do you use the “ladder” method? 1st – Determine your starting point. 2nd – Count the “jumps” to your ending point. 3rd – Move the decimal the SAME number of jumps in the SAME direction. Ex: 4 km = _________ m Starting Point Ending Point How many jumps does it take? 4. 1 __. 2 __. 3 __. = 4000 m

Metric Calculations Common Measurement Conversion Factors Length: 1 mile (mi) = 5,280 feet (ft) 1 kilometer (km) = 1,000 meters (m) 1 centimeter (cm) = 10 millimeters (mm) 1 meter (m) = 39.38 inches (in) 1 inch (in) = 2.54 centimeters (cm) Volume: 1 gallon (gal) = 4 quarts (qt) 1 quart (qt) = 0.95 liters (l) 1 quart (qt) = 32 ounces (oz) Mass: 1 kilogram (kg) = 2.2 pounds (lb) 454 grams (g) = 1 pound (lb) 1 pound (lb) = 16 ounces (oz)

Dimensional Analysis Method of calculation in conversions - Example 1: How many seconds are there in 2.3 days? Unit you want next goes on top Unit you want to cancel out goes on bottom

Dimensional Analysis Example 2: Calculate the number of milliliters in 10.2 gallons of gasoline.

Conversion Factors Problems are given in this format: A x B x D = F C E To solve you enter it into the calculator as follows: A x B ÷ C x D ÷ E = F General idea: every numerator value is multiplied and every denominator value is divided.

Scientific vs. Standard Notation Move decimal until number is between 1 and 10. Number of times moved is the exponent: Moved to the left: Positive Exponent Moved to the right: Negative Exponent Scientific Notation: 54 = 5.4 x 101 70,789 = 7.0789 x 104 0.0898 = 8.98 x 10-2 Standard Notation: 2.44 x 105 = 244,000 7.053 x 10-2 = 0.07053 6.8 x 101 = 68

Calculator Practice Ex: (5.5x105)(2.1x104) = 7.1x103