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Chemistry > Chem test 9th grade > Flashcards

Chem test 9th grade Flashcards

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1
Q

What is atomic mass

A

It is how many grams in a mole

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2
Q

How much is one mole

A

a collection of 6.02 x 10^23 things

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3
Q

Is a mole a molecule

A

no

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4
Q

Who discovered moles

A

Avogadro

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5
Q

what is a molecule

A

It is a combo of two or more atoms held together by chemical bonds

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6
Q

What do subscripts tell you

A

how many of each atom there are in one molecule

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7
Q

how do you go from number of particles to number of moles

A

divide by avogadros number

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8
Q

What is avogadros number

A

6.02 x 10^23

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9
Q

how do you go from number of moles to mass

A

multiply by molar mass

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10
Q

how do you go from mass to number of moles

A

divide by molar mass

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11
Q

how do you go from number of moles to number of particles

A

multiply by avogadros number

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12
Q

moles to litres

A

do moles x 22.4

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13
Q

litres to moles

A

litres / 22.4

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14
Q

1 mole of gas =

A

22.4 litres

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15
Q

molar mass number =

A

atomic mass number

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16
Q

to balance equations, you must

A

add coefficients to make all elements equal on either side

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17
Q

what are ions

A

atoms with a positive or negative charge due to the loss/gain of electrons

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18
Q

what is an covalent bond

A

elements that share electrons

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19
Q

What is an ionic bond

A

when elements lose/gain an electron

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20
Q

What is electronegativity

A

how strong an atom is (can it steal your electrons) The measure of an atom’s ability to attract electrons to itself

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21
Q

What is the strongest and weakest electronegativity

A

4 is strongest, 1 is weakest

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22
Q

Why do covalent bonds occur

A

Because the two elements are too similar in electronegativity and therefore can’t steal so therefore share

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23
Q

what is relative atomic mass?

A

the average atomic mass of all the naturally occurring isotopes of a given element

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24
Q

How is atomic mass measured

A

in Amu which is 1/12 the mass of carbon 12

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25
Q

How many atoms are there in 12 grams of carbon 12?

A

there are 6.02 x 10^23 atoms

26
Q

To find the molar mass of a compound do

A

multiply the subscript by the atomic mass of all the elements
then add together all the numbers

27
Q

How is energy increased

A

temperature

28
Q

What conditions are needed for a reaction to occur

A

minimum kinetic energy
collide with each other
be facing the correct way when they collide

29
Q

What does higher concentration do

A

when theres higher concentration, there are more particles to collide meaning more collisions.
greater chance of successful collisions results in more product made in the same time

30
Q

What does collision theory state

A

that for a reaction to occur, the particles involved must collide with the correct orientation and sufficient energy

31
Q

Higher surface area means

A

more room for reaction to occur. The larger the surface area, the faster the reaction occures

32
Q

What element are humans primarily made from

A

carbon

33
Q

what happens after two half lives and after three?

A

after one you get 1/2, after two you get 1/4, after three you get 1/8 and so on

34
Q

What does endo stand for

A

inside (cold

35
Q

What does exo stand for

A

outside (hot)

36
Q

What does thermic stand for

A

heat

37
Q

What is activation energy

A

the minimum amount of energy colliding particles need for a collision to be successful and for a reaction to occur

38
Q

what is an exothermic reaction

A

a chemical reaction during which heat is released into surroundings

39
Q

What is an endothermic reaction

A

a chemical reaction during which heat is absorbed form the surroundings

40
Q

What does an exothermic graph look like

A

It is flat where the reactants are
there is a curve up then down
then the products are flat below where the reactants where

41
Q

What does an endothermic graph look like

A

reactants are flat line
curve up to products
products are flat line above reactants
x axis is reaction progress
y axis is potential energy

42
Q

What is a catalyst

A

a substance that increases the rate of a chemical reaction without itself undergoing any permanent change, by lowering the activation energy

43
Q

what is the rate of chemical reactions

A

speed at which reactants turn into products

44
Q

how do you calculate the average rate of reactants

A

either
change in mass of reactants used / time taken
change in mass of products used / time taken
answer is in cm^3 per second
time is always seconds

45
Q

what does a graph look like when you use quantity of reactants

A

y axis is mass of reactants
x axis is time
line curving down in a slide

46
Q

What does a graph look like when you use the volume of product

A

y axis is volume of products
x axis is time
line curves upward in a rainbow

47
Q

What are factors that affect rate of a chemical reaction

A

temperature
surface area
concentration/pressure
catalyst

48
Q

If particles don’t have enough energy then…

A

nothing happens

49
Q

Rate also depends on

A

frequency of collisions
amount of energy particles have

50
Q

How does temp affect rate of chemical reaction

A

particles gain more energy which causes them to move faster, and collide with more energy

51
Q

How does pressure/concentration affect rate of chemical reaction

A

as pressure/concentration increases, there are more particles per unit of volume, making collisions more frequent

52
Q

How does surface area affect rate of chemical reaction

A

higher surface ares means more area for collisions to occur which means frequency of collisions would be higher

53
Q

How does a catalyst affect rate of chemical reaction

A

catalysts lower activation energy creating a higher proportion of successful collisions

54
Q

When are reactions the fasted?

A

At the beginning, then they slow down until they stop

55
Q

How do you tell if one reaction is faster than the other

A

Whichever line is steeper is the faster reaction

56
Q

how to determine percentage yield

A

(actual yield / theoretical yield)100

57
Q

how to find actual yield

A

(percentage x theoretical)100

58
Q

Why does percent yield exist

A
  1. reactants might not all react or begins to reverse
    • slow reaction and not all reacts
  2. side reactions
  3. some is lost during the process
    • spilled
    • left in the container
59
Q

relative vs molar mass

A

relative - mass of a single molecule
molar mass - mass of a mole

60
Q

triangles

A

grams / moles x molar mass
particles / moles x 6.02 x 10^23

Chemistry (5 decks)

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