Chem lab exam

-          Accuracy - how close a measured value is to the true value

-          Precision - how close a set of measured values are to each other

-          Resolution - is the smallest distinguishable change that can be measured accurately.

-          Random error – occurs due to chance and includes fluctuations in measurements

-          Systematic error - caused by the measuring device itself and is consistently either above or below the true value.

-          Dilution equation – C1V1 = C2V2, C is concentration, V is volume

-          Beer’s law - states that if monochromatic radiation is allowed to fall on a solution, then the amount of light absorbed or transmitted is an exponential function of the concentration of the absorbing substance and of the length of the path of light through the sample

o   𝑇 =10^−𝑎𝑏𝑐 or −log10𝑇 = 𝑎bc

o   T = transmittance

o   b = path length

o   a = constant depending on the substance absorbing the light

o   c = concentration

o   A = absorbance: A= - log T

-          Colorimetry - measurement technique used to determine the concentration of a particular compound in a colored solution

-          Spectrophotometers: the amount of light absorbed or transmitted is accurately and quantitatively detected and measured by solid state electronic devices

-          Electromagnetic radiation: is energy that can be described as existing in small “packets” (photons) or in terms of waves depending on the way it is observed.

-          Spectroscopy: the study of the interaction of electromagnetic radiation with matter

-          White light: a particular sample containing all wavelengths of visible light

-          Absorption: electron move from low to high energy state (excited state), energy absorbed

-          Emission: electron from an excited state to ground state, high to low, energy released

-          Chromatography: separation technique that uses two phases of different polarity to separate components of a mixture

-          Stationary phase: is a porous substance

-          Mobile phase: fluid that can flow through the porous stationary phase

-          Paper chromatography: Nonpolar components will have a higher affinity for the mobile phase, will spend more time in the mobile phase, and will travel further. Polar components will have a higher affinity for the stationary phase, will spend more time in the stationary phase, and will travel less

-          Rf = distance spot traveled/distance solvent travels from spotting line

-          Reverse phase (liquid) chromatography: any situation which the stationary phase is less polar than the mobile phase

-          Solution – homogeneous mixture of two or more substances

-          Solute – substance that is present in a smaller amount

-          Solvent – substance present in the larger amount

-          Dissolution – involves the breaking of bonds and the formation of new associations

-          Solubility – the concentration of solute in a saturated solution at a specific temperature

-          Water is a polar covalent molecule

-          Nonpolar substances – not very soluble in water

-          Dissociation – solute breaks apart into smaller components

-          Electrolytes – presence of charged ions in solution will allow the solution to conduct electricity

-          Non-electrolyte – solute does not conduct electricity

-          Acidic cation – react with water to produce H+

-          Neutral cation – do not react with water

-          Convection – mass transport by moving fluid

-          Diffusion – spontaneous decrease in concentration differences due to random molecular motion

-          Like dissolves like

-          Qualitative analysis – finding out what elements or substances are present in the sample

-          quantitative analysis – determining how much of each component is in the sample

-          Arrhenius acid – anything that produces H+ when added to water

-          Arrhenius base - anything that produces OH- when added to water

-          Bronsted-Lowry bases – proton acceptors

-          Bronsted-Lowry acids – proton doners

-          Lewis acid – electron pair acceptor

-          Lewis base – electron pair donor

-          Acid-base indicator – substance that changes colors at different pH values

-          Hygroscopic – solid attracts water from the atmosphere

-          Titration – technique used to determine the concentration of an unknown solution through the slow addition of a solution of known concentration

-          Equivalence point – acid is completely reacted with the base

-          M1V1=M2V2 , M= molarity, V=volume

-          Back titration – the concentration of an analyte is determined by reacting it with a known amount of excess reagent. The remaining excess reagent is then titrated with another, second reagent.

-          Calorie – amount of energy required to raise temp of 1 g of water by 1 C from a standard temperature at one atmosphere pressure

-          Food calories - relationship between energy and our bodies

-          1000 calories = 1 food calories = 1 Calorie = 1 kcal

-          Calorimetry – experiment where an reaction will cause a temperature change to the surroundings, then we determine how much energy was released or absorbed

-          Calorimeter – device that allows you to measure the change in temp due to chemical reaction

-          Specific heat - amount of energy required to raise the temp of 1 g of a substance by 1 C

-          q=mCT