EXPERIMENTAL CHEMISTRY CHEAT SHEET, Cheat Sheet of Chemistry

Download EXPERIMENTAL CHEMISTRY CHEAT SHEET and more Cheat Sheet Chemistry in PDF only on Docsity! u/baguetteroni  Experimental Chemistry  AP Chemistry (Barron's C14)    Table of Contents  Data Gathering  Calculations  Graphs  Determination of Physical Properties  Sample Manipulations  Separation Techniques  Instrumental Techniques  Experimental Reactions  Qualitative Analysis of Inorganic Ions  Chemical Hazards   Safety Principles and Equipment    Data Gathering  ● Quantitative VS Qualitative   ○ Quantitative ​→ numerical (ex - concentration of acid it .345 ​M ​)  ○ Qualitative → ​not numerical (ex - when silver nitrate is added to a solution  and a white precipitate)  Calculations  ● 2 basic approaches  ○ Dimensional analysis ​→ converts information from one set of units to  another  ○ Memorized equation or law where you just plug n’ chug  ● Accuracy VS Precision  ○ Accuracy ​→ closeness between the measurement obtained and the true  value  ■ Generally it's impossible to determine the accuracy with certainty  ■ Measure value using two independent methods to have more  confidence in accuracy of results  ○ Precision → ​closeness of repeated measurements to each other  ■ All the values recorded are extremely similar (note that they CAN be  very inaccurate though)  ■ Precise ≠ Accuracy   ■ Measure of ​indeterminate errors ​- errors that arise in estimating the  last, uncertain, digit of a measurement; random errors and cannot be  eliminated  ● Significant figure ​ rules  u/baguetteroni  ○ Significant if: digit is not zero, zero is in between two other numbers, trailing  zero is in a number w/ decimal point  ○ Not significant if zeros are all to the left of all nonzero digits  ○ Exact numbers ​ → have no uncertainty and are exactly known (ex - one  dozen of eggs is 12 eggs, not 12.001); considered to have infinite sig figs  when doing math  ○ Math rules  ■ Multiplication and division - number with fewest significant figures  determines number of sig figs in answer  ■ Addition and subtraction - number w/ fewest decimal places  determines the number of decimal places in answer  ● Uncertainty  ○ Absolute uncertainty ​- uncertainty of the last digit of a measurement (45.47  mL last digit is uncertain) (for addition/subtraction)  ○ Relative uncertainty ​- absolute uncertainty divided by the number itself (for  multiplication/division)  ● Rounding   ○ Number of digits to be kept determined with sig fig rules  ○ If number after kept digits is left than 5 → round down  ○ If number are kept digits is 5 or more → round up  ● Significant figures in atomic and molar masses  ○ Make sure to first determine the number of sig figs the answer must have  Graphs  ● Graph ​→ used to illustrate the relationship between two variables w/ two aces  (x-axis and y-axis)  ● X-axis is normally the independent variable while y-axis is normally the  dependent variable   ● Make sure to remember to label the axes, number the axes, plot the data points,  and (not always) draw the line of best fit  Determination of Physical Properties  ● Scale reading  ○ Parallax errors ​- fluid level or meter pointer is never directly in contact with  scale, incorrect reading results leads to parallax errors  ○ Meniscus ​- surface tension of a liquid in any container causes liquid to  have curved surface  *ALWAYS MEASURE BOTTOM OF MENISCUS*  ● Determination of mass by weighting  ○ Weight = gravitational constant * mass