Unit 1 - Fundamentals of Chemistry

Question 1

solids

Answer 1

• definite shape and volume
• tightly packed in a orderly manner
• jiggle/vibrate in a fixed position

Question 2

liquids

Answer 2

• fixed volume, no definite shape
• closely packed and arranged in a disorderly manner
• particles move about sliding and rolling past each other freely in random motion

Question 3

gases

Answer 3

• no fixed shape and volume
• particles are far apart in a random manner
• move freely at high speeds

Question 4

how do substances heat

Answer 4

by absorbing energy

Question 5

how do substances cool

Answer 5

• by losing energy

Question 6

melting

Answer 6

takes place when particles in a solid ABSORBS ENOUGH ENERGY
to overcome the forces holding them in fixed positions
and rearranges themselves to form a liquid

Question 7

boiling

Answer 7

takes place when liquid particles gain enough kinetic energy
to overcome the forces holding holding them together
and move apart to form a gas

Question 8

freezing

Answer 8

takes place when liquid particles loses energy to
rearrange themselves to form back the solid structure

Question 9

condensation

Answer 9

when the gas particles loses energy and move close together
to reform the liquid structure

Question 10

evaporation

Answer 10

a physical process that changes liquids to gas

Question 11

difference between boiling and evaporation

Answer 11

evaporation
- occurs any temp below boiling point
- occurs only at liquid surface
- no bubbles formed
- occurs slowly

Question 12

proton number

Answer 12

is the atomic number

Question 13

nucleon number

Answer 13

is the atomic mass
number of neutron + number of proton

Question 14

ions

Answer 14

• have an unequal number of proton and electrons
• have an electrical charge

Question 15

positive ions

Answer 15

• cations
• atoms that lose electrons and have more protons

Question 16

negative ions

Answer 16

• anions
• atoms that gains electrons and have less protons
• mainly from non metal atoms

Question 18

isotopes

Answer 18

• atoms of same element that have the same number of protons and electrons
  but different number of neutrons
• mass number different, atomic number same

Question 19

properties of isotope

Answer 19

• identical in chemical reactions
• because they have same no of proton and electrons in outer shell
• uncharged neutrons make little difference to chemical properties
• but affects physical e.g mp and density

Question 20

chromatography

Answer 20

technique for separating mixtures into their components in order to
analyse, identify, purify, and quantify the mixture

Question 21

how chromatography works

Answer 21

1. draw a line 1.5 - 2.0 cm above the bottom edge of paper strip using a pencil and ruler
2. write 2-3 crosses approximately 1 cm apart = so that they are evenly spaced
3. dip a capillary tube into one of the food dyes and put a small spot on the cross
   (repeat this for other food dyes solution)
4. put about 1 cm of water into the bottom of your beaker
5. ensure water is not touching ink spot
6. fold the top of your paper over the top of a splint and
   place the splint on top beaker

Question 22

rF value

Answer 22

• baseline from spot/solvent front
• same rF value = same compound
• different rF value = diff compounds

Question 23

filtration steps

Answer 23

1. filter paper must be folded into a cone
2. measure mass of filter paper so that they can determine the mass of the precipitate after experiment
3. filtrate is collected in a beaker = must be washed out using STIRRING ROD and WASH BOTTLE of distilled water
4. the insoluble solid (precipitate) that was collected on filter paper is dried in an OVEN
5. by taking the mass of filter paper before the filtration and the mass of paper and solid after it dries
6. mass of precipitate can now be calculated.

Question 24

evaporation steps (after filtration)

Answer 24

1. after filtration, the students evaporated the filtrate solution to seperate it from any DISSOLVED SOLUTE
2. the liquid (solvent) from filtrate solution will evaporate leaving behind any dissolved solute
3. saturated solution as a solution containing the maximum concentration of a solute dissolved in solvent at a specified temperature

Question 25

crystallisation

Answer 25

- its a separation technique that in the formation of pure solid particles from a solution containing the dissolved substance 1. as one substance evaporates, the dissolved substance comes out of solutions and collects as crystals 2. produces highly pure solids

Question 26

distillation

Answer 26

- a method used to separate a liquid from a solution by evaporation followed by condensation. 1. heat solution 2. solvent boils and turns into vapour (as it has the lowest bp) 3. vapour cools and condenses back into liquid 4. the solute (e.g salt) is left behind

Question 27

fractional distillation

Answer 27

- separating 2 of more liquids that are mixed together 1. mixture is heated 2. liquid with lower boiling point evaporate first 3. the fractionating column allows better separation by preventing early condensation 4. vapour condenses at different levels and collected separately