Conversion Factors: Intro to Stoichiometry 3221.MATH.1 3221.MATH.2

How many minutes have you been alive? To figure your age: Take your age and write it down, followed by a decimal. Figure the number of months since your last birthday, and divide this by 12. This number will go after a decimal.

Two conversion factors can be written for all inequalities Suppose you spent 2.0 hours working on chemistry homework last night. How many minutes is this? You knew the answer to this problem because you knew an inequality 1 hr = 60 min Two conversion factors can be written for all inequalities Numerator  60 min and 1 hour Denominator  1 hour 60 min It is important that the equality you select to construct a conversion factor is a true relationship!!!

Some Common Equalities Quantity U.S. (Standard) Metric (SI) Metric-Standard Length 1 ft = 12 in 1 km = 1000 m 2.54 cm = 1 in   1 yd = 3 ft 1 m = 1000 mm 1 m = 39.4 in 1 mile = 5280 ft 1 cm = 10 mm 1 km =0.621 mi Volume 1 qt = 4 cups 1 L = 1000 mL 946 mL = 1 qt 1 qt = 2 pints 1 dL = 100 mL 1 L = 1.06 qt 1 gal = 4 qts 1 mL = 1 cm3 Mass 1 lb = 16 oz 1 kg = 1000 g 1 kg = 2.20 lb 1 g = 1000 mg 454 g = 1lb Time 1 hr = 60 min 1 min = 60 s

Conversion Factors When an equality shows a relationship for two units from the same system, it is considered a definition and exact. It is NOT used to determine significant figures

Write conversion factors for the relationship for the following pairs of units: a. milligrams and grams b. minutes and hours c. quarts and milliliters

Conversion factors stated within a problem Many times, an equality is specified within a problem that is true only for that problem. The motorcycle was traveling at a speed of 85 kilometers per hour. One tablet contains 500 mg of vitamin C.

Write the possible conversion factors for each of the following statements: There are 325 mg of aspirin in 1 tablet. One kilogram of bananas cost $1.25. Wine is 12% alcohol by volume. A cyclist in the Tour de France bicycle race rides at the average speed of 62.2 km/hr. A 10.0 g sample of sterling silver has a volume of 94.8 cm3.

Given quantity x Conversion factor(s) = Desired quantity Problem Solving Problem solving in chemistry often requires the conversion of an initial quantity given in one unit to the same quantity but in different units. Numerator Given quantity x Conversion factor(s) = Desired quantity Conversion factor(s) Denominator (initial unit) (final unit)

Guide to Problem Solving Using Conversion Factors Always start with what you are given!! (This will be at the top left of your conversion) The units you want to end up with will be at the right of your problem in the same location (top/bottom) All units should cancel out except for the one(s) wanted. Conversion factors should be set up to ensure cancelling of unwanted units. Numbers across top will be multiplied. The numbers in the denominator are divided.

How many minutes are in 2 years?

The recommended amount of sodium in the diet per day is 2400 mg The recommended amount of sodium in the diet per day is 2400 mg. How many grams of sodium is that? 1 g = _____ mg

If 1890 mL of orange juice is prepared from concentrate, how many liters of orange juice is that? 1 L = _______ mL

An antibiotic dosage of 500 mg is ordered An antibiotic dosage of 500 mg is ordered. If the antibiotic is supplied in liquid form as 250 mg in 5.0 mL, how many mL would be given?

One medium bran muffin contains 4. 2 g of fiber One medium bran muffin contains 4.2 g of fiber. How many ounces (oz) of fiber are obtained by eating three medium bran muffins if 1 lb=16 oz.

You need 4. 0 ounces of a steroid ointment You need 4.0 ounces of a steroid ointment. If there are 16 oz in 1 lb, how many grams of ointment does the pharmacist need to prepare.

A physician has ordered 0. 50 mg of atropine, intramuscularly A physician has ordered 0.50 mg of atropine, intramuscularly. If atropine were available as 0.10 mg/mL of solution, how many milliliters would you need to give?

During surgery, a patient receives 5. 0 pints of plasma During surgery, a patient receives 5.0 pints of plasma. How many milliliters of plasma were given? (1 quart = 2 pints)

A patient needs 0. 024 g of a sulfa drug A patient needs 0.024 g of a sulfa drug. There are 8-mg tablets in stock. How many tablets should be given?

The physician has ordered 1 The physician has ordered 1.0 g of tetracycline to be given every 6 hours to a patient. If your stock on hand is 500-mg tablets, how many will you need for 1 day’s treatment? (Hint: Begin with 1 day)