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Flashcards in QUAL AND QUAN Deck (13)
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1

test and analyze materials and the materials' properties

analytical chemists

2

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

qualitative analysis

3

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

quantitative analysis

4

make new and improved materials

synthetic chemists

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

gravimetric analysis

6

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

volumetric analysis

7

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

indicators

8

common laboratory technique used in volumetric analysis

titration

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)

the end point

10

3 Ways to Determine the Presence of a Species

- Indicators
- Precipitation reactions
- Solution color changes

11

Acid Rain in a Bag

- 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)

12

Industrial Uses of Qualitative Analysis

- 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

13

Volumetric Analysis Calculations

- 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