Question

4. Which of the following solutions has the highest number of sodium ions?
The answer is 50.00 mL of 0.125M NaCl but I'm not sure how to calculate it

Answer 1

what are other options?

Answer 2

i'll show you how to calculate it using other options and then you will try with the one you are saying is the answer

Answer 3

Here's all the options
20.00 mL of 0.200M NaCl
25.00 mL of 0.175M NaCl
30.00 mL of 0.145M NaCl
50.00 mL of 0.125M NaCl
100.00 mL of 0.0500M NaCl

Answer 4

which one do you want me to try aside from the right one?

Answer 5

Any one you'd like.

Answer 6

lets do 30.00 mL of 0.145M NaCl

Answer 7

so i'll start going stepwise
i'll explain how to do
and give formulas
you will calculate
agreed?

Answer 8

Okay

Answer 9

so the q is ' highest number of sodium ions '
for us to get there we have several steps

now first to start
when you look at whats given
30.00 mL of 0.145M NaCl
what do you see?
volume and concentration, right?
now question for you
what can you find if you have these two?

Answer 10

I'm not completely sure. Sorry.

Answer 11

alright
you can find mole
here is the formula
concentration= mole / volume
concentration unit is mole/dm3 which is basically M (molar)
volume unit in the formula has to be dm3
do it and then use this formula and find mole

Answer 12

0.145 M Nacl/ 30.00=.005?

Answer 13

look carefully at unit of volume

Answer 14

unit has to be dm3 while yours is mL

Answer 15

Should it be 30.00^3?

Answer 16

Or 30 x 3?

Answer 17

nope
1000 mL = 1 dm3
30 mL = ? dm3

Answer 18

.33 dm3?

Answer 19

okay look
1000mL = 1 dm3
30mL = X dm3
so its
\[1000mL \times X = 30mL \times 1 dm3 \]

Answer 20

if you make X as subject it will be
= 30/1000

Answer 21

Ooops. I did 1000/30 at first. 30/1000=.03
So it's .03 dm3?

Answer 22

yep)

Answer 23

now solve it
the formula

Answer 24

0.145/.03 dm3=4.83 dm3?

Answer 25

Or should the dm3 drop off and just leave 0.145/.03=4.83?

Answer 26

nope look
the formula is
\[concentration = \frac{ mole }{ volume }\]

Answer 27

if you make mole as subject
its gonna be
\[mole= concentration \times volume \]
isnt it?

Answer 28

Sorry. My computer is having some issues today and keeps shutting down on me.
Okay now I'm confused. You said it wasn't 0.145/ 30.00 which is moles/volume

Answer 29

0.145 M
is not mole
its concentration!
mole is what you are supposed to find

Answer 30

Is that not mole? it says M beside it which means mole

Answer 31

no
M is molar which is concentration!
mole's unit is gram/amu pretty much

Answer 32

its always written as mole though
mole, and its unit as mole

Answer 33

Okay. Got it. So I'm dividing what by .03 exactly?

Answer 34

you are not dividing
look at the formula

Answer 35

It's mole over volume

Answer 36

;yes but you are trying to find mole!
so we have to rearrange the formula
originally the formula is
concentration = mole/ volume
we need mole
so we have to make mole as a subject of this formula
mole = concentration * volume
so now if we make mole as subject- we have to multiply concentration by volume

Answer 37

So would that make it 0.145x.03?

Answer 38

yes

Answer 39

0.145x.03=.004

Answer 40

yep

Answer 41

so now u found mole of NaCl
from here
since we now have mole of the whole compound
we can find mole of sodium alone!

Answer 42

mole= mass/molecular mass
0.004 = total Mr
X = Mr of sodium
total mole * Mr of sodium / total Mr = mole of Sodium

Answer 43

so im just using simple math
if 0.004 mole is mole of whole NaCl
what is mole of Na?
since we know molecular masses of Na and Cl
you can calculate the total molecular mass of NaCl compound
and then take molecular mass of sodium alone

so 0.004 mole = molecular mass of NaCl
and X mole of sodium alone = molecular mass of sodium
so if we do cross multiplication we will get
0.004mole * molecular mass of sodium / molecular mass of NaCl = X moles of sodium alone

Answer 44

do you get it?

Answer 45

So the molecular mass of sodium in 22.99 so it's 0.004x22.99/0.004?

Answer 46

look carefully at the formula please

Answer 47

0.004mole * molecular mass of sodium / molecular mass of NaCl = X moles of sodium alone
its divided by molecular mass of NaCl

Answer 48

You said that 0.004= molecular of NaCl. I got confused by that. The molecular mass of NaCl is 58.44 so the formula would be 0.004*22.99/58.44?

Answer 49

that is mathematically we are making equation that way
yes this one is correct

Answer 50

The answer it 2.047

Answer 51

good job
now last step
multiply mole of sodium by Avogadro's number and you will get number of sodium ions
Avogadro's number is 6.022* 10^23

Answer 52

2.047x6.22x10^23=12.732x10^23

Answer 53

yep

Answer 54

do same thing with the right answer
and then compare these final answers
see the difference for yourself

Answer 55

0.125x.03=.00375
.00375x22.99/58.44=.0015
.0015x6.022x10^23=.009x10^23

Answer 56

Okay what did I do wrong because that's smaller

Answer 57

you are mixed up numbers

Answer 58

volume in your right answer is 50mL! not 30mL like we did just now

Answer 59

So the first step it 50/1000 which is ,05

Answer 60

yep

Answer 61

then 0.125x.05=.006

Answer 62

.006*22.99/58.44=.0023

Answer 63

*.0024

Answer 64

When you multiply that by 6.022 x10^23 it comes out smaller too

Answer 65

oh wait!

Answer 66

0.004*22.99/58.44
you calculated it wrong!!!

Answer 67

thats why it seems smaller

Answer 68

0.0016
this is the answer

Answer 69

multiply it by avogadro's number
now it will be right

Answer 70

sorry didnt notice your wrong answer as i was not calculating myself

Answer 71

Oh hey. That'll do it

Answer 72

all good now?

Answer 73

So the answer to this one it .014

Answer 74

Which is bigger. Finally.

Answer 75

good)

Answer 76

Fantastic. Thank you so much!

Answer 77

you are welcome :))))