U6 - Experimental techniques

Question 1

What is the instrument + SI unit used for time

Answer 1

Stopwatch
Seconds(s)

Question 2

Def: Temperature

Answer 2

measure of the average kinetic energy of the particles.

Question 3

How does alcohol move up thermometer

Answer 3

Liquid in bulb expands when heated, and moves up the capillary tube

Question 4

Temp SI unit and its amount in *C

Answer 4

Kelvin, 273.15 *C

Question 5

Def: Mass

Answer 5

Mass is the amount of matter in a body/object,

Question 6

instrument used to measure mass and its SI unit

Answer 6

Balance scale
Kg

Question 7

Measuring instruments of volume

Answer 7

Measuring
Cylinder Pipette
Burette

Question 8

Unit of volume

Answer 8

cm3

Question 9

Characteristics of pure substances

Answer 9

• Elements / compounds
• One kind of substance
• Constant composition
  atoms for every one oxygen atom in water.
• Melt and boil at specific constant temperatures
• Can only be separated by chemical reactions

Question 10

Characteristics of impure substances

Answer 10

• Mixtures
• 2 or more substances added together with no chemical bonds between the substances
• Different substances in varying amounts
• Melt and boil over a range of temperature
• Separated by physical means

Question 11

What are the methods of purification

Answer 11

Filtration
Crystallisation
Recrystallisation
Simple distillation
Fractional distillation
Fractional distillation in crude oil

Question 12

Explain briefly Filtration

Answer 12

Insoluble substance separated
from a liquid

Question 13

Briefly explain crystallisation

Answer 13

Remove a soluble solid dissolved in a liquid.

Question 14

.Briefly explain recrystallisation

Answer 14

An impure compound is dissolved in a hot solution, then cooled allowing the substance
to crystallise

Question 15

Briefly explain simple distillation

Answer 15

A pure liquid is obtained from a solution.

Question 16

Briefly explain fractional distillation

Answer 16

Separates two of more liquids of which the range of boiling points between the liquids is
less than 50°C.

Question 17

Briefly explain fractional distillation in crude oil

Answer 17

used to to refine crude oil int separate materials.

Question 18

Explain what Paper chromatography is

Answer 18

Separates a mixture by passing it in solution or suspension through a medium in which the components move at different rates.
The least soluble substance is left behind first, while the most soluble substance is carried the furthest

Question 19

What are locating agents used for

Answer 19

used to identify colourless substances.

Question 20

How do you get Rf values

Answer 20

Rf values = distance travelled by the spot relative to the distance travelled by the solvent