Midterm Content Flashcards
Define Scientific Method
Stepwise methods to find answers to scientific questions
A repeatable process for finding scientific evidence of natural phenomena
Steps of the Scientific Method
- Make Observations
- State Key Questions
- State Hypothesis
- State Prediction
- Conduct Scientific Investigation
- Analyze Results
- Form Conclusion
Variables in a Controlled Experiment
Independent variable - manipulated by the investigator
Dependent variable - measured or recorded by the investigator
Controlled variable - variables that are held constant
Calculation for Mean
Sum of numbers / sample size
Calculation for Median
Middle number of a set; average the middle two numbers if there is no middle value
Calculation for Mode
Most frequently occurring number in a set
Calculation for Range
Largest number - smallest number
Metric Conversion
Milli (m) = 1/1000 = 10^-3
Micro (u) 1/1,000,000 = 10^-6
Nano (n) = 1/1,000,000 = 10^-9
Pico (p) = 1/1,000,000,000 = 10^-12
mg (milligram) = 10^-3 g
ug (microgram) = 10^-6 g
ng (nanogram) = 10^-9 g
pg (picogram) = 10^-12 g
Concentration of Solution Calculation
Concentration of solution = amount of solute / volume of solution
Example of Molar Concentration
MW of NaCl = 58.54
1.0 M NaCl (aq) = 58.54 g/liter solution
Mass Concentration: Percent Weight / Volume
% w/v concentration = (amount of solute (g) / volume of solution (mL) ) x 100%
Volume Concentration: Percent Volume / Volume
% v/v concentration of solution = (amount of solute (mL) / volume of solution (mL) ) x 100%
Balancing Microfuge Rotor
- Place on opposite sides (triangle shape with 3)
- Put in one extra tube with equal volume if you only have 5 tubes
Absorption Spectrum
Found by measuring the absorbance of an uncharacterized solution over a range of wavelengths and plotting the absorbance value on the Y-axis and the wave length on the X-axis
Absorption Maxima (maximum)
Any pure substance in solution is the wavelength where absorption is the greatest
