Lab assessment

Question 1

addition and subtraction sig figs

Answer 1

the decimal places have to be the same as the smallest dp

Question 2

multiplication and division sig figs

Answer 2

the answer has to be in the amount with the least amount of sig figs

Question 3

log sig figs

Answer 3

the significant figures are after the decimal

Question 4

constant volume calorimeter

Answer 4

bomb calorimeter

Question 5

constant pressure calorimeter

Answer 5

nested styrofoam cups

Question 6

system in the nested coffee cups

Answer 6

the reaction

Question 7

surroundings in the coffee cups calorimeter

Answer 7

solution, insulator and stir bar

Question 8

the y-intercept of the temperature vs time graph represents

Answer 8

the final temperature of the reaction if it were to occur instantaneously

Question 9

how to calculate experimental enthalpy

Answer 9

delta H = -q sol / n

(n = moles of limiting reactant)
(q sol is enthalpy change of solution)

Question 10

how to calculate expected enthalpy

Answer 10

to products minus reactants with the sum of the enthalpies of formation

Question 11

more concentrated solutions have

Answer 11

lower freezing points (harder to freeze)

Question 12

steps to solve for molar mass

Answer 12

1. plug in what you have
2. if you don’t have molality, plug in everything else and solve for it
3. set moles of solute = kg solvent x molality
4. then divide grams of solute by the moles
5. molar mass

Question 13

non electrolytes vant hoff factor

Answer 13

i = 1

Question 14

electrolytes vant hoff factors

Answer 14

i = number of ions

Question 15

color spectrum values

Answer 15

• violet is the lowest (380-450)
  -red is the highest (620-750)
  ROYGBV
  r- 130
  o- 30
  y-20
  g-75
  b-45
  v-70

Question 16

when you see a color what is happening

Answer 16

it’s reflecting the opposite region (draw color wheel the counter clockwise way)

Question 17

we see what?

Answer 17

we see the complimentary color of what’s being absorbed. example If blue is being absorbed, we see orange. example if green is being absorbed we see red

Question 18

lambda max

Answer 18

max absorbance

Question 19

we used the calibration curve to solve for

Answer 19

molar absorbtivity (eb)

Question 20

how to use M1V1=M2V2

Answer 20

m1= concentration of original solution
v1= volume of solution that’s taken out
m2= new concentration
v2= new volume after added (total volume)

Question 21

calibration curve

Answer 21

a model that shows how a dependent variable varies across a range of standard solution.

Question 22

never force trend line through

Answer 22

0,0

Question 23

Absorbance corrected =

Answer 23

absorbance (max)- 750