Laboratory

Question 1

Diff accuracy and precision

Answer 1

• Accuracy is the measure of how correct a measurement is compared to some standard.
• precision is the measure of how exact a measurement is compared to the real value of the measurement.

Question 2

Methods of seperation

Answer 2

• Filtration: porous paper is used as a filter. it is allowed to dry with solids, and then it’s weight is measured and subtracted from it’s original to get mass of solid.
• distillation: uses diff in boiling points. More volatile liquids evaporate first leaving less volatile liquids.
• chromatography: separation according to how substances are absorbed on a surface. and the ones that stick and the ones that stick to the surface with greater attraction will move more slowly than those that are not attracted.

Question 3

flame tests of alkali metals and alkaline earth metals

Answer 3

Red-Lithium, Strontium
Orange-Calcium
Yellow-Sodium
Green-Barium
Violet-Potassium

Question 4

Gas evolution can be measured by

Answer 4

a manometer also measures air pressure by showing mercury displacement. b/c pressure is how we measure amount of gases.