The Beginning

 Identification/usage of glassware and equipment  When diluting acids ALWAYS add the acid to the water to prevent spattering due to heat build up in the solution.  When transferring solids use a spatula/scoopula and NEVER use your hands.

 To prevent spattering when transferring liquids one may use a glass rod near the mouth of the reagent bottle.  NEVER heat a stoppered piece of glassware!  Define the term meniscus: Curve that forms at the top of a liquid in a glass container due to adhesion of particles to the container.

 Determining percentage error in an experiment: %error = (measured value - accepted value) x100% accepted value Example: Determine the percent error in an experiment in which the experimental value for volume is 21.20mL and the accepted value is 22.4mL. Table T has various formulas.

 What is Scientific Notation? number expressed as the product of two (2) factors: 1st: a number from 1 – 9 2nd: a power of 10  Why would we put numbers into Scientific Notation? To simplify larger numbers or very small numbers

Convert the following into scientific notation:

 When using instruments with indicated markings, all indicated values are certain. An estimated value between two markings is said to be uncertain.  Significant figures: include ALL certain digits and one uncertain digit, no more no less!  Example: Which numbers are certain in 7.15cm? How many significant figures does it contain?

 All NON-ZERO numbers are significant  Zero is significant if:  it is between two (2) non-zero numbers [2007]  whenever you see a decimal point in a number, find the first number other than zero and count [2.00]

 Zero is NOT significant if:  it serves only to hold the place of a decimal [0.239 or 20770]  NOTE: if a decimal point follows, a zero becomes significant [20770.]

 The answer is rounded to be no more precise than the least precise measurement. Look at the decimal place it goes to.  Example: Add the following and round to the correct degree of significance g + 2.6g g  Example: Subtract mL – 86.3mL

 Answers should contain no more (no less) significant figures than the least precise measurement.  Example: Multiply 24.24cm x 43.9cm  Example: Divide 5.1g/213L

 What is a unit? An indicator for the form of measurement used [cm, L] Note: Selected units in chemistry can be found on Table D  Why is it necessary to use units in any scientific measurement? To compare measurements to make them make sense Example: How tall are you? [6 what? Eggs, meters, pounds?]

 Examples of units in measure:  4gmass  75mLvolume  15cmlength  Tools needed for measure:  Balance  Graduated cylinder  Ruler

Table D  PrefixFactor Decimal PlacesSymbol  kilo k  m,L,g m,L,g  centi c  milli m  micro   nano n  pico p

 Note the appropriate factor and number of places that you must shift the decimal point when converting: (make an L or a 7) moving the decimal the total number of places (ignoring sign).  For Example: to convert from nanograms to kilograms you will move 12 spaces to the left (9+3=12).

Now using the above table and "sliding decimal rule", perform the following conversions: 1) 460 g= __________mg 6) 1.30 L= _________mL 2) 312 cm = __________m 7) 3.02 g= __________kg 3)1002 mL= __________L 8) g= __________  g 4)100 kg= ___________g 9) cm= ________km 5)8.23 m= __________mm 10) 560  g= __________kg

 Precision: The reproducibility and the reliability of data during multiple trials of any one experiment.  Accuracy: The nearness to the correct or accepted measurement.

 Measured lab data should be accurate and precise  Measurements that are showing precision in data but are not accurate could indicate problems with instruments, contaminated materials etc. The reproducible results indicate a careful worker.