Topic 1 - Stoichiometry Flashcards

(35 cards)

1
Q

what’s the name of the phase change when solid -> Gas

A

sublimation

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2
Q

what’s the name of the phase change when solid -> liquid

A

melting

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3
Q

what’s the name of the phase change when Gas -> Solid

A

deposition

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4
Q

what’s the name of the phase change when Liquid -> Gas

A

boiling evaporation

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5
Q

what’s the name of the phase change when Liquid -> solid

A

freezing

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6
Q

what’s the name of the phase change when gas -> liquid

A

condensation

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7
Q

what are the state symbols for
solid
liquid
gas
aqueous

A
  • (s)
  • (l)
  • (g)
  • (aq)
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8
Q

what is aqueous solutions

A

solutions formed by dissolving a solid in a liquid

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9
Q

Physical change

A

a substance only changes from one phase to another, without forming new substance.
eg, H2O(s) -> H2O(l)

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10
Q

chemical changes

A

result in formation os new chemical substance.
the atoms in the reactants are rearranged to from new product.

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11
Q

facts about chemical changes refer to (Law of conservation of mass)

A

In a chemical reaction matter is not created or destroyed.
1, number of atoms R=P
2, atoms of reactant has been rearranged to form the product.

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12
Q

what are the two groups of matter

A

1, Pure substances
- element and compounds
2, Mixtures
- homogeneous or heterogeneous

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13
Q

definition of elements

A

Is a substance that cannot be broken down into a simpler substance by chemical means.
- all known elements can be found on the Periodic Table

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14
Q

definition of molecules

A

Electrically neutral group of two or more atoms bonded together.
H2,Cl2,N2

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15
Q

electrically neutral

A

An object that has a balance of protons and electrons.
Opposite=charged objects

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16
Q

Definition of compound

A

Formed from two or more different elements chemically joined in a fixed ratio.
eg. H2O

17
Q

key fact of compounds

A

They have different properties from the element that they are made from.
eg. 2Na+Cl2->NaCl
chlorine poisons gas and reactive metal = table salt

18
Q

Definition of mixture

A

They contain more that on element and/or compound that are not chemically rounded together and so
- retain their individual properties.

19
Q

two types of Mixture

A

1, homogeneous mixture
- have a constant composition throughout.
- they are mixed together.
2, heterogeneous mixtures have visibly different substance or phase.
- does not mix

20
Q

what can you do when balancing a chemical equation

A

only change the number in front of the R and P – coefficients.
H2O -> 2 H2O

21
Q

% Atom economy (equation )

A

% Atom economy = molar mass of the desired P / molar mass of all reactants x 100.
100 - the %AE = wasted reactants

22
Q

what is the unit of mole

23
Q

state 2 equations to calculate moles

A

1, mol = mass/molar mass (n=m/M)
2, mol = concentration x volume (n=cV)
V must be in dm^3

24
Q

definition of mole

A

it is the SI unit for amount of substance (n),
1 mol = 6.02 x10^23 elementary entities.

25
the number of Cl molecules and Cl atoms in 1.00 mol of Cl gas, Cl2.
- 6.02 x 10^23 molecules of Cl2 - 6.02 x 10^23 2x6.02 x 10^23 = 1.2x10^24 Cl atoms
26
state the definition of relative atomic mass (Ar)
is the weighted average mass of the naturally occurring isotopes of an element relative to 1/12 the mass of an atom of C-12. - find on PT - eg. H = 1.01
27
definition of AMU
Atomic mass unite, which has a mass of 1.66 x 10^-27
28
calculating relative atomic mass (Ar)
Ar = (relative abundance x mass of the isotope) +()+() / 100
29
state the definition of relative molecular mass (Mr)
Is the weighted average mass of a molecule relative to 1/12 the mass of an atom of C-12. - is the sum of the Ar of the atoms in the molecule. - eg, H2O = 2x H (1.01) 1 xO (16) 16 + 2x1.01 = 18.02
30
the unit of Molar mass
g mol^-1
31
Molar mass definition (M)
Is the mass in grams of one mole of a substance. - one mole of substance contain 6.02 x 10^23 particles. - numerically = relative atomic mass.
32
Molar mass for molecules
The the sum of all (number of the atoms in the molecule x its Ar) = Mr of the molecule = M
33
converting between cm^3 and dm^3
10^-3 1cm^3 x 1dm^3/1000cm^3 = 0.001dm^3
34
where and what is Molar ratio
the Coefficients in the balanced equation tells the mol of R and P 2A + 3B -> C + 2D 2 mol of A react with 3 mol of B to form C and 2 mol of D - one reactant is limiting and one is excess.
35