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54 Cards in this Set
- Front
- Back
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precision
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experimental values are all close to one another
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accuracy
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experimental values are close to correct values
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systematic error
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- can be discovered and corrected
- usually wrong in a particular direction (i.e. miscalibration) -fault of equipment |
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random (indeterminate) error
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- limitations in the ability to make physical measurements
- can come from estimating errors - can be wrong in more than one direction (may estimate a little more or a little less than correct value) |
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normal distribution
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- a bell curve, where the expected experiential values are in the center, and should be seen the most often when testing
- happens when only random error is involved |
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mean
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(sum of values) ÷ (number of measurements
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standard deviation
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√((sum of the the squares of the deviation from the mean) ÷ (# of observations-1))
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degrees of freedom
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number of observations -1
used to determine standard deviation |
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Q-test
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Q= (gap) ÷ (range)
used to decide whether an outlier should be rejected |
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analytical balance
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used for weighing
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tare
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setting something (i.e. the electronic balance) equal to 0 for calibration
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weighing by difference
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weigh a container full of a substance, pour some out, weight the container again to see how much substance has been poured out
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sensitivity
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how many decimal places something measures to
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meniscus
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-dip at top of water in a tube
- measure from the bottom of the meniscus -occurs because of surface tension, water is more attracted to glass that other water molecules. |
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intensive property
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a measurement that does not change based on the amount of a substance
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density
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D = mass ÷ volume
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conductors
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conduct electricity (metals)
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semiconductors
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conduct some electricity (semimetals)
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insulators
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dont conduct electricity (nonmetals)
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direct current
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electricity flows through something in only one direction
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alternating current
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the current of electricity that flows through something in oscillating back and forth
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voltage
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the electrical force that pushed charge through the conductor
V=IR I = current R = resistance |
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current
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the quantity of electrons passing a point in one second
measured in amperes |
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resistance
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how much a conductor resists the flow of atoms
measured in ohms |
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power
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the work performsd by all electrical current
P = VI measured in Watts (W) 1W = 1 J/s |
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electric circuit
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any arrangement of electrical materials hat allows a current to flow through
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transducer
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converts energy from one form to another
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desiccator
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used for drying substances
(uses CaCl2 in this case) |
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stoichiometry
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the precise numerical relationship between quantities of reactants and products in a chemical reaction
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electrolyte
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a substance with ions dissolved in it
conducts electricity (the ions are positive and negative) |
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siemens (S)
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the unit for measuring conductance
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conductometric titration
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using conductivity measurements to tell how much of a certain substance needs to be added to bond to all of the lose electrons in a solution
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First Law of Thermal Dynamics
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the total energy in the universe must always remain constant
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exothermic
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releases energy/heat (gets hotter)
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endothermic
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absorbs energy/heat (gets colder)
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heat of reaction
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(heat of products) – (heat of reactants)
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state function
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i.e. enthalpy- a rection will always give off/absorb the same amount of energy, no matter what path is taken to get from the reactants to the products.
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calorimeter
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a device used to measure the heat or reaction. all the energy of a reaction expressed as heat, and the heat that is release or absorbed by the reaction makes water in the calorimeter heat up or cool down
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heat capacity
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the amount of heat it takes to raise the temperature of a substance by 1˚C
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specific heat
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the amount of heat it takes to raise the temperature of 1 gram of a substance by 1˚C
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heat or reaction (qrxn)
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-(qsoln + qcal)
qsoln = mass • ∆T • specific heat qcal = calorimeter constant • ∆T |
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light waves
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c = wavelength • frequency
c = speed of light |
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Balmer seires
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the light spectrum of a hydrogen atom
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Balmer's Equation
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∆E = Rh ((1/nf^2) – (1/ni^2))
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spectroscope
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used to view the light spectra
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transmission diffraction grating
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small piece of glass or plastic with grooves in it that diffract light, so different frequencies show up at different points on the graph of the spectroscope
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electrical discharge tube
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tube containing metal electrodes and a low pressure gas. when a high voltage is passed through the electrodes, it emits light.
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atomic emission spectrum
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the light waves that a certain element produces (measured by a spectroscope)
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continuous emission spectra
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certain lights (like fluorescent lights) emit waves of so many different frequencies that the light overlaps and the spectra looks like a rainbow
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pyrolysis
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burning a substance to ash and burning all of the carbon out of it
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colorimetry
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the process of using a machine which measures light absorption to determine the amount of substance in a solution
(measured by subtracting the amount of light transmitted through a substance from the amount of light originally emitted by the machine) |
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photodiode
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measures how much light is transmitted through a substance in a colorimeter
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Beer's Law
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A = e•b•c
A = absorbance = log (1/T) T = transmittance = (light transmitted through solution) ÷ (light transmitted through blank solution) e = molar extinction coefficient b = path length of light c = concentration of units of molarity |
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Beer's Law Plot
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graph of absorbance vs. solution molarity
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