Fundamentals of chemistry 2

Question 1

what is an isotope?

Answer 1

isotopes are different forms of the same element, that have the same number of protons, but a different number of neutrons.

Question 2

what is the pH scale.

Answer 2

a scale to tell how alkaline or acidic something is.

Question 3

what color does a pH 14 alkaline turn in universal indicator?

Answer 3

purple

Question 4

acid + metal –> _____+______

Answer 4

acid + metal –> salt+ hydrogen

Question 5

acid + metal oxide –> _____+_____

Answer 5

acid + metal oxide –> salt+ water

Question 6

acid + metal carbonate –> ____ + ____

Answer 6

acid + metal carbonate –> salt + carbon dioxide

Question 7

what is a displacement reaction?

Answer 7

A displacement reaction occurs when a more reactive element displaces, or pushes out, a less reactive element from a compound that contains the less reactive element.

Question 8

what was rutherfords gold foil experiment?

Answer 8

he fired a beam of alpha particles onto some gold foil surrounds by a substance that flashed when in contact with the alpha particles. when he fired them most went straight through others were deflected back and some of them where redirected off course.

Question 9

what were rutherfords conclusions from the gold foil experiment?

Answer 9

1)most of an atom is empty space.
2)the center(nucleus) has a positive charge

Question 10

how do you work out relative atomic mass ?

Answer 10

sum of(an isotope abundance x the isotope mass)
—————————————————-
sum of abundance of all the isotopes

e.g
(69.2 x 63) + (30.8 x 65) / 69.2 + 30.8

Question 11

what equipment do you need for filtration?

Answer 11

filter paper, filter funnel, conical flask

Question 12

what equipment do you need for evaporation?

Answer 12

evaporating dish, tripod, gauze, heat proof mat, bunsen burner.

Question 13

what might simple distillation be used for?

Answer 13

separating out solutions with different boiling points

Question 14

what is fractional distillation used for?

Answer 14

seperating mixtures of similar boiling points (liquids).

Question 15

what is a fractionating column?

Answer 15

a tube full of little glass rods that is cooler at the top than the bottom.

Question 16

what was democritus’ theory in 500 b.c

Answer 16

that everything was made up of things called atoms that could not be separated any further

Question 17

what was John dalton’s theory

Answer 17

-all matter is composed of atoms
-atoms of each element are the same size, mass ,ect., but are different from atoms of other elements.
-atoms can’t be subdivided(cut) or destroyed
-atoms are tiny solid balls

Question 18

what did JJ.thomson believe?

Answer 18

he believed that the electrons were like “plums” embedded in a positively charged “pudding”

Question 19

who did the gold foil experiment?

Answer 19

Ernest Rutherford

Question 20

what was niels bohr’s theory

Answer 20

he suggested that the electrons orbited the positive nucleus in shells

Question 21

What part of the atom did James Chadwick discover?

Answer 21

the neutron

Question 22

what makes a atom stable

Answer 22

a full outer shell

Question 23

what is the atomic number

Answer 23

the amount of protons (so therefore ,also the amount of electrons).

Question 24

what are the noble gasses

Answer 24

elements with full outer shells so they don’t really react much

Question 25

who created the periodic table?

Answer 25

dimiti mendelev.

Question 26

what is in the top left of an element on the periodic table and what does it tell us?

Answer 26

mass number (number of protons and neutrons)

Question 27

what does it tell you if an element is in group 2?

Answer 27

that its outer-most shell has 2 electrons in it

Question 28

what does it tell us if an element is in period 3?

Answer 28

it has three shells

Question 29

what do you call group 1

Answer 29

alkali metals

Question 30

what do you call group 7 ?

Answer 30

halogens

Question 31

what makes something an acid?

Answer 31

any substance that forms an aqueous solution with a pH less than 7

Question 32

what ions do alkalis form in water?

Answer 32

OH- ions (hydroxide ions)

Question 33

what products do you get if you react a acid with a base?

Answer 33

salt + water

Question 34

what does pH scale measure?

Answer 34

the concentration of Hydrogen ions

Question 35

what makes something more reactive than something else?

Answer 35

how easily it can gain or lose electrons.

Question 36

what is titration?

Answer 36

a way of figuring out the concentration of an acid by working out the specific amount of alkali that is needed to react with it to neutralise it.

Question 37

what is the method for titration?

Answer 37

1) use a pipette to transfer 25cm³ of sodium hydroxide solution into a conical flask 2)Add 5 drops of indicator such as Phenolphthalein to the alkali in the conical flask 3)place the conical flask on a white tile so we can see a colour change more clearly 4)fill a burette with sulfuric acid 5)add acid to the alkali until the solution is neutral. we need to add the perfect amount for this to happen. once we start to see a colour change go drop by drop. 6)read the volume of acid added from the burette.

Question 38

what is the method for making copper sulfate crystals out of copper oxide and sulfuric acid

Answer 38

1. Heat up 25cm3 of sulfuric acid until almost boiling, to increase the rate of reaction between the acid and copper oxide. 2. Add a small amount of copper oxide using a petri dish and stir slowly with a glass rod. Repeat this until there is clearly powder left at the bottom after stiring, this shows that the acid is fully reacted. 3. Using filtration seperate out the excess copper oxide for the copper sulfate solution. 4. Place the solution into an evaporating dish and boil at a low temperature until half of the solution remains. 5. Leave the solution in the evaporating dish in a cool dry place for 24 hours to fully crystallise.

Question 39

what is the symbol equation for copper sulfate?

Answer 39

CuSO₄

Question 40

what is chromatography?

Answer 40

Chromatography is a process for separating components of a mixture.

Question 41

how does chromatography work

Answer 41

Chromatography is based on the principle where molecules in a mixture are applied onto a surface (stationary phase)and are separating from each other while moving at different speeds with the aid of a mobile phase.

Question 42

why might one component of a mixture go really high on the chromatography paper.

Answer 42

as it has a greater affinity to the mobile phase than the stationary phase

Question 43

how do you work out Rf value?

Answer 43

distance of sample / solvent front

Question 44

what is the solvent front?

Answer 44

how far you let the water travel up the paper.

Question 45

what is gas chromatography?

Answer 45

where you seperate a mixture of gases by dissolving them in a mobile phase and making them travel up a tube filled with bits of stuff (the stationary phase). you time how long it takes for the components to travel up the tube.

Question 46

how does a fractionating column work?

Answer 46

it works as it forces any solution that is not fully a gas (a vapour) to come in contact with the beads and drip back down into the mixture.