GENERAL Flashcards
(42 cards)
1
Q
ammonium ion
A
NH4 +
2
Q
Hydrogen ion
A
H+
3
Q
silver ion
A
Ag+
4
Q
hydroxide ion
A
OH-
5
Q
nitrate ion
A
NO3 -
6
Q
hydrogen carbonate ion
A
HCO3 -
7
Q
carbonate ion
A
CO3 2-
8
Q
sulphite ion
A
SO3 2-
9
Q
sulphate ion
A
SO4 2-
10
Q
Phosphate ion
A
PO4 3-
11
Q
phosphoric acid
A
H3PO4
12
Q
potassium permanganate
A
KMnO4
13
Q
how to convert from
1. mm to cm
2. cm to m
A
- mm/10 = cm
- cm/100 =m
14
Q
how to convert from
1. milligrams to grams
2. grams to kilograms
3. kilograms to tones
A
- mg/1000 = g
- g/1000 = kg
- kg/10000 = tonne
15
Q
how to convert from
1. cm3 to dm3
2. cm3 to m3
A
- cm3/1000 = dm3
- cm3/10^6 = cm3
16
Q
a substance + oxygen =…
A
= (substance) oxide
17
Q
metal + water = …
A
= metal hydroxide + hydrogen
18
Q
metal + acid = …
A
= salt + hydrogen
19
Q
oxide + acid = …
A
= salt + water
20
Q
hydroxide + acid = …
A
= salt + water
21
Q
carbonate + acid = …
A
= salt + water + carbon dioxide
22
Q
hydrogencarbonate + acid = …
A
= salt + water + carbon dioxide
23
Q
ammonia + acid = …
A
= ammonium salt
24
Q
metal carbonate ( + heat) = …
A
= metal oxide + carbon dioxide
25
Describe the stages to make a standard solution of 250cm^3
1. Weigh sample bottle on 2.d.p balance
2. Transfer to a beaker, re-weigh bottle and calculate difference in mass/mass of sample used
3. Add distilled water to the beaker and stir using a glass rod until all solid has dissolved
4. Transfer solution and washings from beaker + glass rod to a volumetric flask using a funnel
5. Make the solution in the volumetric flask up to 250cm^3 by adding distilled water
6. Add a stopper and invert the flask 3 times
26
Why is weighing by difference used
- making a standard solution
- determines accurate mass added
- not all of the substance will have been transferred
27
Why are washings from the beaker and glass rod added to the volumetric flask
- making a standard solution
- reduces chances of losing any solution during transfer
- ensures all moles of the solute are transferred
- using distilled water does not affect the moles
28
- what is the final stage of making a standard solution
- why is this imperative
- add stopper and invert the flask 3 times
- mixes the content, creating a uniform solution
29
Describe one precaution if using anhydrous sodium hydrogensulfate (NaHSO4) to make a standard solution
- making a standard solution practical
- ensure it is not too old to make sure water has not been picked up
- this would affect the mass of the compound
30
What can be done to ensure the meniscus is read properly
- making a standard solution
- use white paper behind dark liquids
- read at eye level
31
How can we reduce mass uncertainty
- making a standard solution
- use a larger mass, allowing more room for error
- weighing by difference, ensures accurate measurements of mass
32
Describe the stages to perform an acid-base titration
- practical
1. Rinse beaker with solution that is going to be used + ensure jet space doesn’t contain air bubbles
2. Fill burette with solution of known concentration, using a funnel (then remove funnel)
3. Use pipette + filler to add 25cm^3 of standard solution into 250cm^3 conical flask on top of a white tile
4. Add 2-3 drops of phenolphthalein/indicator to flask and record initial colour
5. Record initial burette volume, using bottom of meniscus
6. Perform rough titre, until colour change, record final burette reading
7. Repeat, adding the solution from burette dropwise near the end point
8. Swirl flask, ensure all contents are in flask by washing sides with distilled water
9. Repeat until 2 concordant results
33
What are concordant results
- acid base titration
Results within 0.1cm^3 of each other
34
- what is the burette rinsed with
- why
ACID BASE TITRATION
- the solution that is going into it
- ensures concentration is not affected
35
- will leftover distilled water in the burette affect final titre
- why
- how
ACID BASE TITRATION
- it may increase the final titre
- distilled water will decrease the concentration of the solution going into the burette
- more of it will be needed to neutralise the other substance
- Ex. Acid will be more dilute, so a higher volume of it will be needed to neutralise the base
36
- what should be checked in a burette before performing a titration
- why
ACID BASE TITRATION
- ensure there are no air bubbles in the jet space
- this will increase the titre read
37
State 2 mistakes that may increase a titre and how to fix them
ACID BASE TITRATION
1. Any leftover distilled water in the burette
- rinse the burette with the solution that is going into it next
2. If there are air bubbles in the jet space
- open the tap of the burette and let the solution run through to remove air bubbles
38
What result will any distilled water in the conical flask have on the titre
- how
- why
ACID BASE TITRATION
- no change/affect
- it will not affect the moles in the solution
39
Why is a white tile used in an acid base titration
PRACTICAL
To allow for a more clear colour change to be seen
40
Why should only 2-3 drops of indicator be used
ACID BASE TITRATION
- indicators are acidic
- increase pH
- may affect the titre
41
How to reduce the uncertainty for volumes in a burette
ACID BASE TITRATION
- use a solution of lower concentration in the burette
- higher volume will be required
- more room for error
42
