Chem Lab Final 2
Terms
undefined, object
copy deck
- what does specific heat do?
- identifies an unknown material
- what is a calorimeter?
- insulated container that prevents heat exchange from the process occuring inside the countainer and around it outside.
- heat change of a substance (q)=
- M x C x Change in T
- what is c (specific heat) for water?
- 4.18 j/(g)(degrees c)
- to record a thermogram, what do you press after main menu?
-
F2 - Temperature
F1 - Temperature vs. Time - what is y min and max for determining the calorimeter constant for a styrofoam cup calorimeter?
- 15-75
- what is the equation for deteriming the calorimeter constant for the calorimeter?
- [mass of warm water x C x change in temp of warm water] - [mass of room temp water x C x change in temp of water]
- density = ?
- mass / volume
-
equation for finding the volume of a...
cube:
rectangle solid:
sphere:
cylinder: -
cube: L3
rectangle solid: L x W x H
sphere: 4/3(3.14)(r3)
cylinder: (3.14)(r2)(L) - how do you determine the density of an irregularly shaped object?
- use the displacement of water or some other liquid
- does lower specific heat mean the object absorbs heat more slowly of quickly?
- slowly
- what is the equation for determining the specific heat of an unknown metal given the calorimeter constant?
- [mass of room temp water x C x change in temp of water] + [calorimeter constant x change in temp of water] / [mass of solid x change in temp of solid]
- how do you identify an unknown metal nitrate solution via titration with NaOH
-
1. obtain 20 mL of unknown.
2. pipet 10 mL into a 250 mL
beaker and add about 90 mL
water.
3. fill cleaned pipet with 50
mL NaOH. - how do you preform titrataion using the measurenet workstation?
-
F3 - pH/mV
F2 - pH/volume
calibrate
F1
Display - when done using measurenent, how do you save files?
-
file options
F3
enter 3 digit code
Enter - molarity = ?
- mols / L
- molar ratio = ?
- mol NaOH / mol metal soln
- how do you distinguish an unknown metal nitrate solution via precipitation with NaOH?
- molar ratio
- how do you prepare the five standard solutions from the one concentrated standard soltuion when determining the concentration of an unknown metal solution by absorbance spectrascopy?
-
(m1)(v1)=(m2)(v2)
solving for v1 - on measurenet, how do you preform absorbance spectrascopy?
-
F5 spectroscopy
F2 absorbance - for absorbance spectrascopy, what does y = and what is your min/max?
-
y = absorbance
max = 2
min = 0 - for absorbance spectrascopy, what does x = and what is your min/max?
-
x = wavelength
min and max = leave how it is. - for absorbance spectrascopy, what is your blank solution?
- water
- for absorbance spectrascopy, what is used to zero? to reference?
-
zero = black block
reference = water - volume should be reported to the what mL?
- 0.001
- will a higher or lower specific heat attain a higher equilibrium (final temperature)
- higher
- how do you find lamba max when preforming absorbance spectrascopy?
- look at the three beer lambert plots given. it will be the peak that is around 1 or less for absorbance. use the highest peak that's the best (least blurry)
- how do you find the absorbance needed when preforming absorbance spectrascopy?
- plug absorbance reading at lamda max intot equaiton for line (given), solving for x.
- how do you determine whether an unknown compound is ionic, polar covalent or nonpolar covalent?
-
ionic: use LE light. if it lights up, it's ionic.
polar: will dissolve in water (and not hexane)
nonpolar: will dissolve in hexane (and not water) - when you standardize an unknown acid via titration, what goes in the buret?
- the acid
- how do you determine the concentration of the unknown acid (or base)?
-
take grams of standaard
divide by molar mass
multiply by mol-to-mol ratio (2 humps=2 to 1 ratio, 1 hump=1 to 1 ratio)
then divide by equivilance point (in L) - how do you find the quivilance point?
- what you start with - wht you finish with
- when standardizingn an unknown base via titration, what goes in the buret?
- the base
- when determining the % mass in an unknown compound in a mixture via titration, what goes in the buret?
- the unknown compound
- how do you find the % mass in an unknown compound in a mixture via titration?
-
equivalence point (in L)
multiply by molarity (given)
now you have moles.
multiply moles by molecular weigth (should be given)
divide teh weight that you started with
multiply by 100%