Stoichiometry Flashcards

1
Q

Definition of a substance

A

matter with constant composition. All particles have the same properties.

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2
Q

Definition of a mixture

A

Matter with variable composition. Made from two or more substances that are not chemically bonded and so retain their original properties.

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3
Q

Definition of a homogenous mixture

A

a mixture made up of particles that are uniformly distributed

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4
Q

Definition of a heterogenous mixture

A

a mixture made up of particles that are not uniformly distributed

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5
Q

Common Polyatomic ions

A

Ammonium - NH4+
Carbonate - CO3 2-
Hydrogen Carbonate - HCO3-
Hydroxide - OH-
Nitrate - NO3-
Nitrite - NO2-
Phosphate - PO4 3-
Phosphite - PO3 3-
Sulfate - SO4 2-
Sulfite - SO3 2-
Oxalic Acid - (COOH)2 2-
Peroxide - O2 2-

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6
Q

Naming anions

A

-ate = max number of O
-ite = less O

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7
Q

Common Acids

A

Phosphoric acid - H3PO4
Ethanoic acid - CH3COOH

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8
Q

Properties of solids

A

particles closely packed
inter-particle forces are strong
particles vibrate in position
fixed shape
fixed volume

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9
Q

Properties of liquids

A

particles more spaced
inter-particle forces weaker
particles can slide over each other
no fixed shape
fixed volume

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10
Q

Properties of gas

A

particles spread out
inter-particle forces negligible
particles move freely
no fixed shape
no fixed volume

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11
Q

What is the kinetic theory?

A

average kinetic energy of the particles is directly related to the temperature of the system

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12
Q

When does a substance melt?

A

a substance melts at the temperature at which the disruptive effect of the vibrations just overcomes the ordering effect of the forces of attraction

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13
Q

When does boiling occur?

A

at a specific temperature, determined by when the vapour pressure reaches the external pressure

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14
Q

What is the mole?

A

it is a fixed number of particles and refers to the amount, n, of substance

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15
Q

Avogadro’s constant

A

defines the mole as the unit of amount in chemistry
6.02 x 10^23

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16
Q

Formula containing n, N and NA

A

moles = (no. of particles) / (Avogadro’s constant)
n=N/NA

17
Q

Relative Atomic Mass definition

A

Ar of an element is the weighted average of the masses of its isotopes relative to 1/12 of the mass of a C12 atom.
Ar = (weighted average of one atom of the element)/(1/12 mass of one atom of C12)
*values do not have units

18
Q

Relative Molecular Mass definition

A

Mr of a substance is the weighted average of the masses of the molecules relative to 1/12 of the mass of a C12 atom.

19
Q

What is the Molar Mass?

A

the mass of one mole of a substance

20
Q

Formula containing n, m and M

A

moles = mass/molar mass
n=m/M

21
Q

what is the Molecular formula

A

it gives the total number of atoms of each type in a molecule
* to calculate need the molar mass

22
Q

What is the Empirical Formula?

A

is a formula which gives the lowest whole number ratio of atoms in a molecule
*assume 100g sample for calculations

23
Q

Limiting Reagent

A

is the reactant that determines the quantity of product

24
Q

% yield calculation

A

% yield = ((mass of experimental yield)/(mass of theoretical yield)) x 100

25
Q

Avogadro’s Law - gases

A

Equal volumes of all gases, when measured at the same temperature and pressure, contain an equal number of particles.

26
Q

Formula containing amount of gas (n), volume of gas (Vstp) and Molar Volume

A

amount of gas = (volume of gas stp)/(molar volume)
n=V/22.7

27
Q

Standar Conditions for gases

A

T=273K
P=100kPa
Vm= 22.7 dm^-3

28
Q

Kinetic Molecular Theory

A
  • particles are in constant motion
  • that motion depends upon the absolute temperature measured in Kelvin
29
Q

Absolute Zero

A

means that there is no particle motion

30
Q

Temperature definition

A

is a measure of the kinetic energy or motion of particles

31
Q

Pressure definition

A

the force the particles’ collisions on the walls of the container

32
Q

Boyle’s Law

A

Pressure and volume are inversely proportional , as the volume increases the pressure decreases
PV = constant

33
Q

Pressure Law

A

temperature and pressure are directly proportional if the volume is kept constant
P/T = constant

34
Q

Charles’s Law

A

volume and temperature are directly proportional if pressure is constant
V/T = constant

35
Q

Formula for when one of the conditions is changed to a fixed amount of gas

A

P1V1/T1 = P2V2/T2

36
Q

Ideal Gas

A

the particles have negligible volume
there are no attractive forces between the particles
the kinetic energy of the particles is directly proportional to the absolute temperature

  • this model tends to break down at low temps and high pressures
37
Q

Formula containing n, c, V

A

concentration = moles/volume
c=n/V

38
Q

Formula for the diluting of a solution

A

c1V1=c2V2
as the number of moles of solute remains constant