Unit 6: Stoichiometry Section 1: Chemical Calculations

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

Metric Calculations Common Measurement Conversions Common Measurement Conversions Length: 1 mile (mi)=5,280 feet (ft) 1 kilometer (km)=1,000 meters (m) 1 centimeter (cm)=10 millimeters (mm) 1 meter (m)= 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 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. Example 2: Calculate the number of milliliters in 10.2 gallons of gasoline.

Conversion Factors Problems are given in this format: Problems are given in this format: A x B x D = F A x B x D = F C E C E To solve you enter it into the calculator as follows: To solve you enter it into the calculator as follows: A x B ÷ C x D ÷ E = F A x B ÷ C x D ÷ E = F General idea: every numerator value is multiplied and every denominator value is divided. 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: 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 left: Positive Exponent Moved to the right: Negative Exponent Moved to the right: Negative Exponent Scientific Notation: Scientific Notation: 54=5.4 x ,789= x =8.98 x Standard Notation: Standard Notation: 2.44 x 10 5 =244, x = x 10 1 =68

Calculator Practice Ex: (5.5x10 5 )(2.1x10 4 ) = Ex: (5.5x10 5 )(2.1x10 4 ) = 7.1x x10 3