Physical Chemistry Flashcards
(80 cards)
1
Q
What PH does the strongest acid have?
A
0PH
2
Q
What PH does the strongest alkali have?
A
14PH
3
Q
What PH is neutral (water)
A
7PH
4
Q
What does an indicator do?
A
Change colour to show the PH of a solution
5
Q
What colours does universal indicator show?
A
Acidic: Red
Neutral: Green
Alkali: Purple
6
Q
What colours does litmus paper show?
A
Acidic: Red
Neutral: Purple
Alkali: blue
7
Q
What colours does phenolphthalein show?
A
Acidic: Colourless
Alkaline: Pink
8
Q
What colours does Methyl orange show?
A
Acidic: red
Alkaline: yellow
9
Q
What’s an acid?
A
Source of hydrogen ions (H+) with a PH less than 7
10
Q
What’s a base?
A
A substance which can neutralise an acid
11
Q
What’s an alkali?
A
Soluble base with a source of hydroxide ions, (OH-) and PH greater than 7
12
Q
What’s a neutralisation reaction?
A
Acid + Base = salt + water, or H+ + OH- = H2O
13
Q
What PH are the products after a neutralisation reaction?
A
7 neutral
14
Q
What’s the equation when an acid and a metal oxide react?
A
Acid + metal oxide = Salt + water
15
Q
If the acid is hydrochloric acid what will the metal salt be?
A
A chloride
16
Q
If the acid is Sulphuric acid what will the metal salt be?
A
A sulphate
17
Q
If the acid is Nitric acid what will the metal salt be?
A
A nitrate
18
Q
What’s the equation for an acid and a metal Carbonate?
A
Acid + Metal Carbonate = Salt + water + Carbon dioxide
19
Q
What does soluble mean?
A
Can dissolve in water
20
Q
What does insoluble mean?
A
Can’t dissolve in water
21
Q
Which salts are soluble?
A
All except carbonates (few exceptions)
22
Q
How do you make a soluble salt with an acid and an insoluble base?
A
Mix the acid (Nitric acid), and insoluble base (copper carbonate) They will produce crystals, filter and evaporate them
23
Q
How do you make an insoluble salt?
A
A precipitation reaction
24
Q
What’s a precipitation reaction?
A
Mixing 2 solutions with ions you require, to make an insoluble salt and eg barium chloride + Sulphuric acid= Barium Sulphate + hydrochloric acid
25
What are titrations used for?
To find out how much acid is needed to neutralise an alkali (or vice versa)
26
Method for a titration?
Add alkali to a conical flask with an indicator
| Put acid in a burette and add to the alkali until there's the required colour change, and measure how much was used
27
How to work out the concentration from a titration calculation?
Work out the moles of the substance you have
Write the equation for the reaction, and compare the ratio to work out the amount of moles in unknown substance
Work out the concentration of the unknown stuff
28
What's a slow reaction?
Rusting
29
What's a moderate reaction?
Magnesium reacting with acid
30
What's a fast reaction?
An explosion
31
What does the rate of reaction depend on?
Temperature
Concentration (or pressure for gasses)
Catalyst
Size of particles (surface area)
32
Formula for rate of reaction?
Rate of reaction= Amount of reactant used or amount of product formed / Time
33
What's the precipitation method of measuring a rate of reaction?
When the product is a precipitate which clouds a solution and you measure how long until you can't see through the solution
34
What's the change in mass method of measuring a rate of reaction?
Place the reaction on scales and measure how the mass drops as the reaction goes on
35
What's the measuring volume of gas given off method in measuring the rate of reaction?
Use a gas syringe to measure the amount of gas given off during the reaction
36
What's a way of proving that bigger surface area means faster reaction?
React hydrochloric acid with marble chips, with different size chips, and notice the smaller chips produce more gas
37
Why does a larger surface area increase the rate of reaction?
More frequent collisions
38
What's a method to prove that a higher concentration of acid increases the rate of reaction?
React magnesium metal with dilute HCL, and see when the acid is a higher concentration the mass drops down faster
39
How to show how temperature effects the rate of reaction?
Sodium Thiosulfate and HCL produce a cloudy precipitate, so see how long it takes until you can't see through the flask
40
How to show how a catalyst effects the rate of reaction?
Via the decomposition of hydrogen peroxide into water, add manganese to see it increase the rate of reaction
41
What's collision theory?
States that the rate of reaction, depends on how hard and how often the reacting particles collide
42
How does a higher temperature increase the rate of reaction?
Particles have more energy so move quicker, so they collide more often
43
How does a Higher concentration ( or pressure) increase the rate of reaction?
Particles closer together so the important particles will collide and react more often
44
How does a larger surface area increase the rate of reaction?
The particles will have more area to react with, so there will be more successful collisions
45
How does a catalyst increase the rate of reaction?
Gives the reacting particles an area to stick to
| Increasing the successful collisions by lowering the activation energy
46
What causes faster collisions?
Hot temperature
47
Why does a hot temperature cause faster collisions and more successful ones?
Particles have more energy so move faster, and have enough energy to make the reaction happen
48
What happens in a chemical reaction?
Old bonds broken, new bonds made
49
What process is bond breaking?
Endothermic, as energy is supplied to make the bonds
50
What process is bond making?
Exothermic as energy is released when new bonds are formed
51
What's an exothermic reaction?
Gives out energy, in the form of heat, shown by a rise of temperature in the surroundings
So the bond formation is energy is greater than bond breaking energy
52
What's an endothermic reaction?
Takes in energy, in the form of heat, shown by a fall of temperature in the surroundings
So the bond formation is energy is smaller than bond breaking energy
53
What's the overall change in energy in a reaction called?
The enthalpy change ( Delta H)
54
What unit is Delta H?
kj/mol
55
If Delta H is Negative then the reaction is?
Exothermic as heat is given out
56
If Delta H is positive then the reaction is?
Endothermic, as heat is taken in
57
Pointers for Exothermic reaction graph?
Reactants higher than products
Difference in height shows energy change
The initial shows the activation energy
58
What's the activation energy?
The energy required to break the old bonds
59
Pointers for an endothermic graph?
Reactants lower than products
| Difference in height shows energy change
60
What are the axis on an energy level diagram?
```
X= Progress of reaction
Y= Energy
```
61
How do catalysts reduce the activation energy?
They give an alternative reaction pathway
62
What's the formula for finding enthalpy change?
Enthalpy change Delta H = Total energy absorbed breaking bonds - total energy released making bonds
63
Method for finding the Enthalpy change?
Draw out the molecules already there and the molecules made, and using the table work out the total energies
Use enthalpy change equation
64
Experiment to work out enthalpy change?
Calorimetry
65
What's calorimetry used to work out energy transferred in neutralisation, dissolving and displacement reactions
?
Measure the heat of the reagents, then the heat of the solution, whilst insulating it
66
What's combustion calorimetry?
Burn a fuel to see how much fuel it takes to heat water to 50C
Use copper can, and reduce draughts to make it more accurate
67
Equation for energy transferred, in calorimetry?
Energy transferred (joules) = mass of water g x temp change C x 4.2 (energy to heat 1 g of water by 1C)
68
Method for working out energy transferred?
Work out all the things required for the energy transferred equation
Use the energy transferred equation
Work out the mass of fuel used, and work out how much energy whatever mass of the fuel produces
69
What's the molar enthalpy change?
The enthalpy change given out by one mole of the reactant
70
How to work out the molar enthalpy change?
Calculate the amount of energy transferred
Work out the moles of fuel produced the heat by using the mass and Mr
Then divide the energy change (if it was exothermic this number will be negative) by the amount of moles to find the Kj/mol
71
What's a reversible reaction?
Where the products of one reaction, can themselves react to make the original reactents
72
What's an example of a reversible reaction?
Thermal decomposition of ammonia chloride (S)
Breaks down to make ammonia (G) and hydrogen (G) chloride
Which can then re form to make ammonia chloride
73
What's dynamic equilibrium?
Where the forward and backward reactions are equal so the overall effect is nil, happens in a closed sytem (no product can escape)
74
What are all reactions in directions?
Endothermic one way, endothermic the other way
75
How does increasing the temperature effect the reaction?
Endothermic increases to use extra heat up
76
How does reducing the temperature effect the reaction?
Exothermic increases to give more heat out
77
What's the position of equilibrium?
The relative amount of products and reactents
78
What do all gaseous reactions have?
More molecules on one side than the other
79
How does raising the pressure effect the reaction?
Encourages the reaction which produces fewer molecules of gas
80
How does decreasing the pressure effect the reaction?
Encourages the reaction which produces more molecules of gas
