Chem 101 Lab Final

beryllium

Be

silicon

Si

potassium

K

chromium

K

manganese

Mn

cobalt

Co

arsenic

As

tin

Sn

Cs

cesium

barium

Ba

uranium

U

nitrate

NO3

carbonate

CO3

acetate

C2H2O2

sulfate

SO4

chlorate

ClO3

hydroxide

OH

strong acids (Ice Cold Beer Never Sits Chilled Properly)

1. hydroiodic acid (HI)

2. hydrochloric acid (HCl)

3. hydrobromic acid (HBr)

4. nitric acid (HNO3)

5. sulfuric acid (H2SO4)

6. chloric acid (HClO3)

7. perchloric acid (HClO4)

carbonic acid

H2CO3

ammonia

NH3 (base)

potassium hydroxide

KOH (base)

sodium hydroxide

NaOH (base); OH is always hydroxide and all of the bases we need to know have an element + OH

SI unit metric prefixes

1. tera (T) = 10^12

2. giga (G) = 10^9

3. mega (M) = 10^6

4. kilo (K) = 10³

5. deci (d) = 10^-1

6. centi ( c) = 10^-2

7. milli (m) = 10^-3

8. micro (u) = 10^-6

9. nano (n) = 10^-9

10. pico (p) = 10^-12

stoichiometry diagram

coffee cup calorimeter

an insulated cup used to measure the heat released or absorbed during a chemical reaction

heat

the flow of energy caused by a difference in temperature

enthalpy

the quantity of heat emitted or absorbed by a chemical reaction when the reaction occurs under conditions of constant pressure

specific heat capacity

the amount of heat required to raise the temperature of 1 gram of a substance by 1 degree celcius

Arrhenius acid and base

substances that directly produce H+ or OH- ions respectively in aqueous solutions

neutralization reaction

when an acid and a base react to form water and a salt

equivalence point (in a titration)

when the amount of moles of OH- added is equal to the amount of moles of H+ in the solution

how do you find the limiting reactant, theoretical yield, actual yield, and excess reactant

1. covert the grams of reactants to mols and then divide by the mole ratio, whichever one is the lowest is the limiting reactant

2. multiply the moles of LR by mole ratio of (LR/product) and then multiply by molar mass of product

3. actual yield/theoretical yield time 100

4. multiply the moles of LR by mole ratio of (mol ex/mol LR) to find how much ex reacted, convert moles reacted to grams, intial g - g reacted

how to write the molecular, ionic, and net ionic formulas for a reaction

how to find the heat of a solution

q = (mass)(specific heat capacity)(temperature change)

steps to draw lewis structure for molecular compound

1. count total valance electrons (from periodic table charges)

2. figure out central atom (least electronegative atom; electronegativity increases left to right on periodic table and the electronegativity increases as you go down the columns); carbon has a tendency to be the central atom and hydrogen can never be the central atom bc its too small

3. ensure all atoms have 8 valance electrons, other than hydrogen which only needs 2 electrons

how do you determine how many hybrid orbitals

it is equivalent to the number of electron groups around the central atom

how do you know if the molecular geometry is different than the electron geometry

the central atom has a lone pair of electrons attached to it taking up space and altering the bond angles to be less than their electron geometry

how do you know the number of sigma and phi bonds

1. there can only be one sigma bond between the central atom and surrounding atoms

2. any addition bonds to central atoms, such as a double or triple bond, is the 1 phi or 2 phi bonds

how do you know if a molecule can hydrogen bond with itself or not

OH groups and NH ground can hydrogen bond with themselves, no others can

how do you know if a molecule is polar or nonpolar

solution dilution formula

M1 x V1 = M2 x V2

what’s a caliper

an electric device used to measure height and diameter by placing device in between the caliper clamps

how do you determine volume by water displacement

1. put some amount of water in a graduated cylider and measure initial volume

2. drop the device whose volume you are measuring into the cylinder and measure final volume

3. final volume - initial volume

precision

reproducibility; will the procedure produce the same results over and over again

accuracy

closeness to actual

strong electrolytes

any soluble salt or strong acid releasing many H+ ions

weak electrolytes

a compound that releases a few H+ ions; weak acids and sparingly soluble salts

non electrolytes

no H in molecular formula so releases no H+ ions

general lab procedure for ionic precipitation reaction

1. measure and dilute the two reactants to the appropriate molarity and volume

2. mix the two reactants into another beaker and place the magnetic stirrer into the breaker and stir and stirring plate for 15 minutes

3. clean, dry, and label an empty 100mL breaker and a piece of filter paper and record mass

4. place your stirred solution into a vacuum filtration apparatus to help the precipitate dry for 5 minutes

5. move the filter paper with the precipitate into the weighed beaker and let air dry

6. weight mass of precipitate and divide by theoretical yield to find percent yield

general lab procedure for a titration

1. get a ring stand and place a burette clamp on it, then clamp the burette onto one side

2. rinse burette with water and then the sodium hydroxide (base) solution

3. fill the burette with the base and record the starting volume

4. using a volumetric pipette, fill 20mL of the unknown molarity acid solution into an Erlenmeyer flask

5. add 2 to 3 drops of phenolphthalein indicator into the flask and mix

6. place the flask under the burette and begin simultaneously swirling solution with your hand and adding the base

7. continue until there is a persistent light pink color and record the volume of base required

8. use all data collected to calculate molarity of acid solution

how do you find the heat of the reaction from the heat of the solution

qrxn = -qsol; add a negative sign

how do you find delta Hrxn

qrxn/moles of the acid solution

general lab procedure for the quantitative determination of food dyes

1. choose 1 color of dye and make 5 solutions with increasingly larger concentrations of the dye diluted with distilled water

2. use a spectrometer to measure for 90 second and then stop the recording

3. find the max wavelength of solution 5 (10.0 mL dye and 0.0 mL DI water) and record both the max wavelength and the corresponding absorbance

4. repeat for the other 4 solutions and record the absorbance at the max wavelength determined for solution 5

5. find the equation for the absorbance - concentration graph of that dye

6. repeat to the find the equation and the max wavelength for the other 2 dyes

7. fill 3 cuvets with each of the 3 unknown dye drink samples

8. place a sports drink sample in the spectrometer and record their absorbance at the max wavelengths for each of the 3 dyes

9. use the formulas for each of the 3 dyes and plug in the absorbance of the dye in the sports drink for y and solve for x to find the concentration of the dye in the sports drink

10. repeat for all 3 drinks and all three dyes