Question

Please help me with few Acid Base questions!

Answer 1

in the image i understand NR9 , but not 27, 28 and NR 10 beacuse I am not sure how to make the eqaution from looking at the question

Answer 2

let HA be an acid and A- be the conjugate base after dissociation and assume the solvent is water

Answer 3

therefore we have the following equation\[HA \rightarrow A ^{-}+H _{3}O ^{+}\]

Answer 4

Now, Ka is just the equilibrium constant of this equation

Answer 5

understood?

Answer 6

not really

Answer 7

well, acid dissociates in water to form the conjugate base and hydronium according to the equation above. I hope your teacher told you what is the conjugate base of an acid. If not, the easiest way to think of it is to rip off the proton and whatever left is the cb

Answer 8

then will the eqaution look like Nan3 + h20= H30 + ??? somthng like this?

Answer 9

We know that any equilibrium has a constant K which is a ration of forward versus reverse reaction.\[aA+bB \rightarrow cC+dD\]\[\frac{ A^{a} B^{b}}{ C ^{c} D ^{d}}\]

Answer 10

you should use HN3, not NaN3 because NAN3 is not acid so it cannot protinate water

Answer 11

so we have HN#+H2O=H3O+ + N3-

Answer 12

H2O is left out in the Ka expression because solvent is not part of the equilibrium expression

Answer 13

then why does it give NaOH concentration in NR 10?

Answer 14

Because NaOH is used to neutralize HN3

Answer 15

damn this is just confusing then how would u slow it when Naoh is not in the equation we made

Answer 16

Lets get Q27 out first, ok?

Answer 17

okey

Answer 18

I can do that one looking at the eqatuion so I am fine with that question

Answer 19

So Ka is the acid dissociation constant, which is a special case of equilibrium constant, did your teach laugh you these terms?

Answer 20

yes

Answer 21

OK, so you should know product over reactants, constants are powers, stuff like that, right?

Answer 22

yes easy

Answer 23

Great, so what is the dissociate reaction of HN3 with H2O?

Answer 24

what do u mean

Answer 25

\[HN _{3}+H2O \rightarrow H3O ^{+}+N _{3}^{-}\]

Answer 26

I mean this equation

Answer 27

ok what do u want me to do

Answer 28

write the expression for Ka of this reaction

Answer 29

I would say the answer is B

Answer 30

since liquids dont coiunt

Answer 31

Fantastic! 27 solved! You still have problem with 28?

Answer 32

yes

Answer 33

wait first of all

Answer 34

I have to remeber that theory u told me right when making thses eqautions

Answer 35

you just did it right

Answer 36

no i am talking about the ionic eqaution

Answer 37

Well acid donates proton to water to form hydronium ion and conjugate base

Answer 38

makes sense?

Answer 39

alright lets move on

Answer 40

In this case, HN3 is acid, H2O is water, H3O+ is hydronium and N3- is conjugate base

Answer 41

OK, 28 is simple. remember this: if the numeric value for Ka is less than 1, bottom is larger, if it is bigger than i top is larger

Answer 42

there is no chemistry, only math

Answer 43

it's like say 5/7 is less than 1, why? because bottom is large. 7/5 is larger than 1 because top is large

Answer 44

answer is A?

Answer 45

Back to chem, bottom is reactant, top is product, so which side has higher concentration?

Answer 46

let's not jump too fast

Answer 47

why is there no sigh of H30

Answer 48

is Ka larger or smaller than 1?

Answer 49

yes

Answer 50

Ka is smaller than 1, right?

Answer 51

yes

Answer 52

so which side has higher concentration?

Answer 53

bottn is larger

Answer 54

hold up its B!

Answer 55

Great!

Answer 56

Now, onto calculation

Answer 57

i understand nr9 , nr10 is confusing

Answer 58

lets start with basics

Answer 59

how many moles of Hydronium can 1 mole of HN3 produce?

Answer 60

solvent is 1L of H2O of cuz

Answer 61

okay

Answer 62

how many moles of Hydronium can 1 mole of HN3 produce?

Answer 63

not sure.....

Answer 64

\[K _{a}=x^2,x=\left[ H3O+ \right]\]

Answer 65

o yea i know that eqaution wait r u trying to do nr9?

Answer 66

No, but we need this info to do 10

Answer 67

oh

Answer 68

k i already foinf the ph its 2.64

Answer 69

so we have 10^-2.64 mole of H3O+, right?

Answer 70

yes

Answer 71

how many mole of HN3 is 2.2kg?

Answer 72

51.15089514

Answer 73

Great, but three digit is enough for your question

Answer 74

ok

Answer 75

why did they give conc for naoh?

Answer 76

If we have n moles of HN3, we can produce N*10^-2.64 mole of H3O+

Answer 77

which means we need this many mole of NaOH to completely neutralize

Answer 78

molar concentration=mole/liter, right?

Answer 79

yes

Answer 80

we have two of three, can you solve the third?

Answer 81

that's why we need conc of NaOh

Answer 82

we already have the conce its 6.00 mol/l given in the question

Answer 83

Yes, and we know the mole, right?

Answer 84

8.585

Answer 85

wait i am confued ususaly we have an eqaution when we dod these kind of question

Answer 86

Now, can you solve for the liter

Answer 87

that is in liter

Answer 88

I am not sure what are you confused about

Answer 89

where is the eqaution?

Answer 90

like Naoh+hn3?----?

Answer 91

NO!, you don't need that

Answer 92

a molar is 1mole over 1 liter

Answer 93

becuz this is like a chem grade 11 question

Answer 94

now you know how many moles you have, and how many molar you have

Answer 95

we uusaly do some kind of eqautoon to get the moles right

Answer 96

can you find the amount of liter