chemical changes

Question 1

what ions are in acids

Answer 1

H+

Question 2

what type of solution do acids make in water

Answer 2

acidic

Question 3

what type of solution do alkalis make in water

Answer 3

alkaline

Question 4

what ions are in alkalis

Answer 4

OH-

Question 5

pH of neutral solutions

Answer 5

7

Question 6

3 indicators

Answer 6

-litmus paper
-Phenolphthalein
-methyl orange

Question 7

litmus paper : acidic, neutral, alkaline

Answer 7

Red, Purple, Blue

Question 8

Phenolphthalein : acidic, neutral, alkaline

Answer 8

Colourless, Colourless, Pink

Question 9

methyl orange : acidic, neutral, alkaline

Answer 9

Red, Yellow, Yellow

Question 10

metal + acid ->

Answer 10

salt + hydrogen

Question 11

test for hydrogen

Answer 11

Put a lighted splint near the mouth of the test tube. Hydrogen ignites with a squeaky pop

Question 12

acid + metal oxide →

Answer 12

salt + water

Question 13

acid + metal hydroxide →

Answer 13

salt + water

Question 14

acid + carbonate →

Answer 14

salt + water + carbon dioxide

Question 15

test for carbon dioxide

Answer 15

-Bubble the gas through limewater
-Carbon dioxide turns limewater milky/cloudy white

Question 16

what is a base

Answer 16

any substance that reacts with an acid to form a salt

Question 17

what are bases that are soluble in water called

Answer 17

alkalis

Question 18

Neutralisation reaction without spectator ions

Answer 18

H+(aq) + OH-(aq) → H2O(l)

Question 19

how measure pH

Answer 19

-pH probe + meter
-universal indicator + chart

Question 20

method for investigating neutralisation

Answer 20

1. Use a measuring cylinder to add dilute hydrochloric acid to a beaker
2. Dip a clean glass rod into the contents of the beaker. Use it to transfer a drop of liquid to a piece of universal indicator paper on a white tile. Wait 30 seconds, then match the colour to a pH colour chart. Record the estimated pH.
3. Add a level spatula of calcium hydroxide powder to the beaker.
4. Stir thoroughly, then estimate and record the pH of the mixture (as in step 2).
5. Repeat steps 3 and 4 until there are no more changes in pH.

Question 21

apparatus for investigating neutralisation

Answer 21

-measuring cylinder
-beaker
-glass rod
-spatula
-UI paper
-dilute hydrochloric acid
-calcium hydroxide powder

Question 22

hazards for investigating neutralisation

Answer 22

-Hydrochloric acid, concentrated acid is corrosive + damages skin, use dilute hydrochloric acid
-Calcium hydroxide powder, causes skin irritation, wear gloves
-Calcium hydroxide powder, causes serious eye damage, wear eye protection
-Calcium hydroxide powder, may cause respiratory irritation, avoid making a dust

Question 23

dilute concentration definition

Answer 23

contains a relatively small amount of dissolved solute

Question 24

concentrated solution definition

Answer 24

contains a relatively large amount of dissolved solute

Question 25

Strong acids

Answer 25

completely dissociate into ions in solution

Question 26

Weak acids

Answer 26

only partially dissociate into ions in solution

Question 27

what is the pH of a solution

Answer 27

measure of its concentration of hydrogen ions

Question 28

higher the conc of H+

Answer 28

lower the pH

Question 29

lower the conc of H+

Answer 29

higher the pH

Question 30

if solution's concentration of H + ions decreases by factor of 10

Answer 30

pH increases by 1

Question 31

if solution's concentration of H + ions increases by factor of 100

Answer 31

pH decreases by 2

Question 32

naming salts

Answer 32

the first part comes from the metal, metal oxide or metal carbonate. The second part comes from the acid

Question 33

how to make a soluble salt from an acid + insoluble reactant

Answer 33

1. add dilute hydrochloric acid to a beaker 2. add powdered insoluble reactant to acid in a beaker, one spatula at a time, stirring to mix. will effervesce 3. continue adding powder until some unreacted powder is left over - it is in excess 4. filter the mixture in the beaker to remove excess powder 5. allow water in the solution to evaporate to obtain pure dry crystals of the salt.

Question 34

apparatus for making copper sulfate crystals

Answer 34

-measuring cylinder -beaker -glass rod -spatula -evaporating basin -filter -conical flask -water bath -bunsen burner

Question 35

method for making copper sulfate crystals

Answer 35

1. place sulfuric acid in a conical flask + warm it in a water bath 2. add a spatula of copper oxide powder to the acid + stir with a glass rod 3. continue adding copper oxide powder until it is in excess 4. Filter the mixture to remove the excess copper oxide 5. Pour the filtrate (the copper sulfate solution) into an evaporating basin 6. Heat the copper sulfate solution to evaporate half of the water 7. Pour the solution into a watch glass + leave to allow all of the water to evaporate

Question 36

3 main steps for making salts from acids and alkalis

Answer 36

1. Carry out a titration to determine the volumes of acid + alkali that must be mixed to obtain a solution containing only salt + water 2. Mix acid + alkali in correct proportions, as determined in step 1. 3. Allow water in solution to evaporate to obtain pure dry crystals of the salt.

Question 37

apparatus for carrying out a titration

Answer 37

-burette -conical flask -safety pipette filler -pipette -indicator

Question 38

method for carrying out a titration

Answer 38

1. Use pipette + pipette filler to add a measured volume of alkali to a clean conical flask 2. Add a few drops of indicator + put the conical flask on a white tile. 3. Fill burette with acid + note starting volume 4. Slowly add acid from burette to alkali in conical flask, swirling to mix. 5. Stop adding the acid when the end-point is reached (when the indicator first permanently changes colour). 6. Note final volume reading 7. Repeat steps 1 to 5 until you get concordant titres

Question 39

ionic compounds that are soluble in water

Answer 39

-All common sodium, potassium + ammonium salts -All nitrates -Most common chlorides -Most common sulfates -Sodium carbonate, potassium carbonate, ammonium carbonate -Sodium hydroxide, potassium hydroxide, ammonium hydroxide

Question 40

ionic compounds that are insoluble in water

Answer 40

-Silver chloride, lead chloride -Lead sulfate, barium sulfate, calcium sulfate -Most common carbonates -Most common hydroxides

Question 41

what is a precipitate

Answer 41

an insoluble product that forms when two solutions are mixed and react together

Question 42

what is a precipitate reaction

Answer 42

reaction that produces a precipitate

Question 43

how to predict the formation of a precipitate

Answer 43

-if at least one of the products is classed as insoluble

Question 44

empirical =

Answer 44

atomic mass/mass in question then simplify ratio

Question 45

reduction

Answer 45

gain of electrons, loss of oxygen

Question 46

oxidation

Answer 46

loss of electrons, gain of oxygen