Chapter 9: Calculations Used in Analytical Chemistry

Question 1

• method to measure how much a chemical substance absorbs light by measuring he intensity of light as a beam of light passes through sample solution
• basic principle is that each compound absorbs or transmits light over a certain range of wavelength

Answer 1

spectrophotometry

Question 2

visible light wavelength

Answer 2

~400 nm to ~700 nm

Question 3

an unchanging measure of the quantity of matter

Answer 3

mass (m)

Question 4

force of gravitational attraction between that matter and Earth

Answer 4

weight (w)

Question 5

weight maximum at poles

Answer 5

North and South poles

Question 6

weight minimum at poles

Answer 6

Equator

Question 7

always based on mass so that the results will not depend on locality

Answer 7

chemical analysis

Question 8

precision weights used to calibrate weighing instruments and ensure accurate measurements

Answer 8

calibration weights

Question 9

Four fundamental ways of expressing solution concentration

Answer 9

1. molar concentration
2. percent concentration
3. solution-diluent volume ratio
4. p-functions

Question 10

number of moles of that species that is contained in 1L of the solution

Answer 10

molar concentration

Question 11

Three common methods of expressing concentrations in terms of percent

Answer 11

1. weight percent (w/w)
2. volume percent (v/v)
3. weight/volume percent (w/v)

Question 12

has the advantage of being temperature independent

Answer 12

weight percent

Question 13

what is used as a convenient way to express very dilute solutions

Answer 13

parts per million (ppm)

Question 14

formula for ppm

Answer 14

Cppm = (mass of solute/mass of solution) x 10^6 ppm

Question 15

ppm

Answer 15

[ mass solute (mg) / volume solution (L) ] ppm

Question 16

composition of dilute solution is sometimes specified in terms of … ?

Answer 16

volume of more concentrated solution : volume of solvent used in diluting it

(this method is avoided due to ambiguity)

Question 17

negative logarithm (to the base 10) of the molar concentration of that species

Answer 17

p-value or p-function

Question 18

p value formula

Answer 18

pX = -log[X]

Question 19

mass per unit volume

Answer 19

density

Question 20

density unit

Answer 20

• kg/L
• g/mL

Question 21

ratio of its mass to the mass of an equal volume of water at 4C (dimensionless)

Answer 21

specific gravity

Question 22

quantitative relationship among the amounts of reacting chemical species

Answer 22

stoichiometry