topic 3

Question 1

what are alkalis usually

Answer 1

metal hydroxides (solutions)

Question 2

concentration formula

Answer 2

concentration = moles / volume

Question 3

how to get from cm^3 to dm^3

Answer 3

divide by 1000

Question 4

higher concentration of hydrogen IONS means what

Answer 4

more acidic

Question 5

higher concentration of hydroxide means what

Answer 5

more alkaline

Question 6

phenolphthalein indicator

Answer 6

alkaline = pink
acidic = colourless

Question 7

methyl orange indicator

Answer 7

alkaline = yellow
acidic = red

Question 8

litmus solution indicator

Answer 8

alkaline = blue
acidic = red

Question 9

blue litmus paper indicator

Answer 9

blue -> red in acidic
stays blue in alkaline

Question 10

red litmus paper indicator

Answer 10

alkaline: red -> blue
stays red in acidic

Question 11

what happens if pH decreases by one unit

Answer 11

hydrogen ions increase by a factor of 10

Question 12

core practical - investigate change in pH on adding powdered calcium hydroxide or calcium oxide to a fixed volume of dilute hydrochloride acid

Answer 12

add dilute HCl to beaker and measure pH

add weighted mass of calcium hydroxide and stir

record pH

keep adding weighted masses of calcium hydroxide until no more change to pH

draw a line graph with mass on horizontal axis with pH on vertical
draw line of best fit
(ignore anomalies)

Question 13

dilute vs concentrated

Answer 13

concentrated = larger amount of substance in a given volume of solution
dilute = less amount of substance in a given volume of solution

Question 14

what are bases

Answer 14

metal oxides or metal carbonates (solid)

Question 15

what’s a strong acid

Answer 15

completely disassociate (separate or ionise) in water

Question 16

what do weak acids do

Answer 16

partially disassociate (separate or ionise) in water

Question 17

what’s the test for hydrogen

Answer 17

use a burning splint held at the open of a test tube of the gas

created a squeaky pop of its hydrogen

Question 18

test for carbon dioxide

Answer 18

bubble the gas through limewater and it will turn cloudy

Question 19

for any neutralisation reaction with an acid and an alkali the ionic equation is what

Answer 19

H+ + OH- -> H2O

Question 20

How to prepare a dry insoluble salt

Answer 20

mix two solutions

filter mixture

rinse beaker with distilled water and pour through filter paper

pour distilled water over the
precipitate in the funnel

remove filter paper with solid on and dry in a warm oven

Question 21

what is soluble in water

Answer 21

all sodium potassium and ammonium salts

all nitrates

most chlorides

most sulfates

sodium carbonate
potassium carbonate
ammonium carbonate

sodium hydroxide
potassium hydroxide
ammonium hydroxide

Question 22

what’s insoluble in water

Answer 22

silver chloride, lead chloride

lead sulfate, barium sulfate, calcium sulfate

most carbonates
most hydroxides

Question 23

cooper sulfate core practical udon water bath

Answer 23

add excess of copper oxide (insoluble) to your acid (sulphuric acid since it’s copper sulfate)

use a filter and filter paper to filter off any copper oxide that hasn’t reacted (solution should be blue as copper sulfate solution has formed)

evaporate water by placing final solution in a water bath

Question 24

why is excess reactant of an insoluble salt added when preparing an acid

Answer 24

to ensure volume of acid reacts completely

excess reactant removed by filtration to only be left with salt and water

Question 25

titration method used when

Answer 25

both reactants are soluble

Question 26

titration method

Answer 26

add acid to burette using a funnel

record volume in the brhette

add known volume of alkali to conical flask add some indicator (phenolphthalein)

put conical flask on white tile to see colourchange better

add acid to alkali until solution goes colourless

calculate how much acid been added (titre)

repeat until you get concordat titres