QUAL AND QUAN

Question 1

test and analyze materials and the materials’ properties

Answer 1

analytical chemists

Question 2

carried out by the analytical chemist to IDENTIFY the substance (figure out which element, ion, and/or compound is present)

Answer 2

qualitative analysis

Question 3

carried out by the analytical chemist to determine the AMOUNT of a substance in a material

Answer 3

quantitative analysis

Question 4

make new and improved materials

Answer 4

synthetic chemists

Question 5

uses the solubility rules to pull the ion of interest out of solution as a solid. then, the mass of the precipitate formed is measured and used to calculate MASS of unknown ion in the precipitate

Answer 5

gravimetric analysis

Question 6

uses the VOLUME (mL) of a substance of a KNOWN concentration (molarity = moles per liter) to calculate the MASS of another substance

Answer 6

volumetric analysis

Question 7

change color in response to pH movement and visually shows the experimenter that the reaction has run to completion

Answer 7

indicators

Question 8

common laboratory technique used in volumetric analysis

Answer 8

titration

Question 9

the point at which the indicator visually changes color to visually show when all of the unknown substance has been fully consumed by the reaction (reaction stops)

Answer 9

the end point

Question 10

3 Ways to Determine the Presence of a Species

Answer 10

• Indicators
• Precipitation reactions
• Solution color changes

Question 11

Acid Rain in a Bag

Answer 11

• Center well: copper + nitric acid produces copper nitrate + water + nitrogen dioxide gas
  a) NO2 is a yellow brown gas
• Middle wells: distilled water
  a) NO2 gas dissolves easily in water (becomes very acidic)
  b) creates acid rain; orange to red color when add indicator to wells after reaction complete
• Outer corner wells: universal indicator solution
  a) Acid = red (pH0); base = violet (pH14); neutral = green (pH7) - follows ROYGBIV
  b) Change colors as pH falls (green to yellow to orange to red as reaction progress and NO2 forms)

Question 12

Industrial Uses of Qualitative Analysis

Answer 12

• A forensic chemist can analyze soil, blood or paint samples. For example, components in a soil sample taken from a crime scene can be compared with a soil sample taken from a suspect’s shoes.
• Pharmaceutical chemists will need to check for impurities in a sample of a new product.
• Water quality
  a) Environmental chemists may need to determine the presence of a particular metal ion in a sample of water taken from a river.
  a) Filter retailers
  a) Swimming safety

Question 13

Volumetric Analysis Calculations

Answer 13

• Volume of known substance used to reach end point is multiplied by concentration of the known substance to tell you the # of moles of the known substance used in the reaction
• Change to moles of the unknown substance by using the ratio set by the coefficient in the balanced equation (for # of moles)
• Multiply moles of unknown substance by its molar mass (sum of atomic mass) to get mass in grams of the unknown substance