Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry IB > 1. Stoichiometric Relationships > Flashcards

1. Stoichiometric Relationships Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

What are elements?

A

Elements are substances made from one kind of atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are compounds?

A

Compounds are made from two or more elements chemically combined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a mixture?

A

In a mixture, elements and compounds are interspersed with each other, but are not chemically combined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What characteristics do components in a mixture have?

A

This means the components of a mixture retain the same characteristic properties as when they are in their pure form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a homogenous mixture?

A

A homogeneous mixture has uniform composition and properties throughout

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a heterogeneous mixture?

A

A heterogeneous mixture has non-uniform composition, so its properties are not the same throughout

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How could you differentiate between a homogenous and a heterogenous mixture? (qualitative)

A

It is often possible to see the separate components in a heterogeneous mixture, but not in a homogeneous mixture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How could you separate air?

A

fractional distillation - using boiling points

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How could you separate sand and salt?

A

solution and filtration by using solubility in water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How could you separate pigments in food colours?

A

paper chromatography

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How could you separate sulfur and iron?

A

Use a magnet - magnetism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens. to substances in aqueous solutions?

A

In aqueous solutions, ionic compounds dissociate into their ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are spectator ions

A

The ions that do not take part in the reaction are called spectator ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an ionic equation? What does it show?

A

An ionic equation shows only the ions or other particles taking part in a reaction, without showing the spectator ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What types of changes are changes of state?

A

Changes of state are physical changes that are reversible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why are state changes not considered chemical changes?

A

These changes do not change the chemical properties or chemical makeup of the substances involved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

WHat 2 state changes fall under the category of vaporisation?

A

Vaporization includes evaporation and boiling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

WHat is the difference between evaporation and boiling?

A

Evaporation involves the change of liquid to gas, but unlike boiling, evaporation occurs only at the surface and takes place at temperatures below the boiling point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

WHen does boiling occur?

A

Boiling occurs at a specific temperature and takes place when the vapour pressure reaches the external atmospheric pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens between stages 1&2 on a heating curve?

A

Between 1 & 2, the particles are vibrating and gaining kinetic energy and the temperature rises

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What happens between stages 2&3 on a heating curve?

A

Between 2 & 3, all the energy goes into breaking bonds – there is no increase in kinetic energy or temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What happens between stages 3&4 on a heating curve?

A

Between 3 & 4, the particles are moving around and gaining in kinetic energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What happens between stages 4&5 on a heating curve?

A

Between 4 & 5, the substance is boiling, so bonds are breaking and there is no increase in kinetic energy or temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What happens between stages 5&6 on a heating curve?

A

From 5 & 6, the particles are moving around rapidly and increasing in kinetic energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the relative atomic mass?

A

The relative atomic mass (Ar) of an element is the weighted average mass of one atom compared to one twelfth the mass of a carbon-12 atom

26
Q

What is the formula for the relative atomic mass?

A

Ar = weighted average mass of one atom of an element / 1/12 mass of one atomc of carbon-12

27
Q

WHat is the relative isotopic mass?

A

The relative isotopic mass is the mass of a particular atom of an isotope compared to one twelfth the mass of a carbon-12 atom

28
Q

What is the relative molecular mass?

A

The relative molecular mass (Mr) is the weighted average mass of a molecule compared to one twelfth the mass of a carbon-12 atom

29
Q

When is the relative formula mass used?

A

The relative formula mass (Mr) is used for compounds containing ions
It has the same units and is calculated in the same way as the relative molecular mass

30
Q

What is the molecular formula?

A

The molecular formula is the formula that shows the number and type of each atom in a molecule

31
Q

What is the empirical formula?

A

The empirical formula is the simplest whole number ratio of the atoms of each element present in one molecule or formula unit of the compound

32
Q

What type of molecules often have different empirical and molecular formulae?

A

Organic molecules

33
Q

What type of compound is always an empirical formula?

A

The formula of an ionic compound is always an empirical formula

34
Q

what is the limiting reactant?

A

The reactant which is not in excess is called the limiting reactant

35
Q

How would you determine which reactant is limiting?

A

The number of moles of the reactants should be calculated

The ratio of the reactants shown in the equation should be taken into account

36
Q

What are STP conditions?

A

a temperature of 0o C (273 K)

pressure of 100 kPa

37
Q

WHat is the kinetic theory of gases?

A

The kinetic theory of gases states that molecules in gases are constantly moving

38
Q

What 5 assumptions does the theory of gases make?

A

The gas molecules are moving very fast and randomly

The molecules hardly have any volume

The gas molecules do not attract or repel each other (no intermolecular forces)

No kinetic energy is lost when the gas molecules collide with each other (elastic collisions)

The temperature of the gas is directly proportional to the average kinetic energy of the molecules

39
Q

What does the volume a gas occupies depend on?

A

Its pressure

Its temperature

40
Q

What does the ideal gas equation show?

A

The ideal gas equation shows the relationship between pressure, volume, temperature and number of moles of gas of an ideal gas:

41
Q

What is the ideal gas equation?

A 
PV = nRT
P = pressure (pascals, Pa)

V = volume (m3)

n = number of moles of gas (mol)

R = gas constant (8.31 J K-1 mol-1)

T = temperature (Kelvin, K)

42
Q

How do gases exert pressure?

A

Gases in a container exert a pressure as the gas molecules are constantly colliding with the walls of the container

43
Q

What effect does decreasing the volume have on pressure?

A

Decreasing the volume (at constant temperature) of the container causes the molecules to be squashed together which results in more frequent collisions with the container wall
The pressure of the gas increases

44
Q

WHat is the relationship between pressure and volume?

A

The pressure is therefore inversely proportional to the volume (at constant temperature)

45
Q

WHat is BOyle’s law - give equation?

A

Mathematically, we say P ∝ 1/V or PV = a constant

46
Q

How doesi increasing temperature affect volume?

A

When a gas is heated (at constant pressure) the particles gain more kinetic energy and undergo more frequent collisions with the container walls
To keep the pressure constant, the molecules must get further apart and therefore the volume increases

47
Q

What is Charle’s law give the equation

A

The volume is therefore directly proportional to the temperature in Kelvin (at constant pressure)

This is known as Charles’ Law

Mathematically, V ∝ T or V/T = a constant

48
Q

How does increasing the temperature affect gas pressure?

A

Increasing the temperature (at constant volume) of the gas causes the molecules to gain more kinetic energy
This means that the particles will move faster and collide with the container walls more frequently
The pressure of the gas increases

49
Q

What is the relationship between changing gas pressure and temperature, give equation?

A

The temperature is therefore directly proportional to the pressure (at constant volume)
Mathematically, we say that P ∝ T or P/T = a constant

50
Q

What parts of the ideal gas equation can be ignored if there is a fixed amount of gas? What equation is formed?

A

For a fixed amount of gas, n and R will be constant, so if you change the conditions of a gas we can ignore n and R in the ideal gas equation

This leads to a very useful expression for problem solving

p1 v1 / t1 = p2 v2 / t2

Where P1, V1 and T1 are the initial conditions of the gas and P2, V2 and T2 are the final conditions

51
Q

Does the ideal gas equation fit all observations and measurements?

A

The ideal gas equation does not fit all measurements and observations taken at all conditions with real gases

52
Q

When does the relationship between pressure, volume and temperature show significant deviation from the ideal gas law?

WHy does this happen?

A

when the temperature is very low or the pressure is very high

This is because the ideal gas equation is built on the kinetic theory of matter

53
Q

What assmtpions about volume does the kinetic theory of matter make?

A

The kinetic theory assumes that the volume the actual gas molecules themselves take up is tiny compared to the volume the gas occupies in a container and can be ignored

54
Q

How true is the assumption about gases relating to the kinetic theory of matter?

A

This is broadly true for gases at normal conditions, but becomes increasingly inaccurate at low temperatures and high pressures

At these conditions the gas molecules are very close together, so the fraction of space taken up by the molecules is substantial compared to the total volume

55
Q

What assumptions does the kinetic theory of matter make about attractive forces?

A

Another assumption about gases is that when gas molecules are far apart there is very little interaction between the molecules

As the gas molecules become closer to each other intermolecular forces cause attraction between molecules

This reduces the number of collisions with the walls of the container

56
Q

How true is the assumption made by the kinetic theory of matter relating to the ideal gas equation?

A

The pressure is less than expected by the ideal gas equation

57
Q

What are standard solutions?

A

Chemists routinely prepare solutions needed for analysis, whose concentrations are known precisely
These solutions are termed standard solutions

58
Q

How are standard solutions made?

A

They are made as accurately and precisely as possible using three decimal place balances and volumetric flasks to reduce the impact of measurement uncertainties

59
Q

What is volumetric analysis?

A

Volumetric analysis is a process that uses the volume and concentration of one chemical reactant (a standard solution) to determine the concentration of another unknown solution

(technique most commonly used is titration)

60
Q

What apparatus is used during a titration?

A

The volumes are measured using two precise pieces of equipment, a volumetric or graduated pipette and a burette

61
Q

How is the end point/ equivalence point shown in a titration?

A

The end point or equivalence point occurs when the two solutions have reacted completely and is shown with the use of an indicator

Chemistry IB (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions