Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
blahhhhh12345678
Group Title
How many molecules of H2O are there in 1.0 g of H2O?
 one year ago
 one year ago
blahhhhh12345678 Group Title
How many molecules of H2O are there in 1.0 g of H2O?
 one year ago
 one year ago

This Question is Closed

dimensionx Group TitleBest ResponseYou've already chosen the best response.0
in 1.0 grams of H2O. okay so.. You are given grams (mass). To go from mass to molecules, you have to convert: Mass > Moles > Molecules. To go from mass to moles, Divide by the molecular weight. To go from moles to molecules, multiply by 6.02 x 10^23.
 one year ago

abb0t Group TitleBest ResponseYou've already chosen the best response.0
convert to moles. then use avogradro's number \(6.022 \times 10^{23}\frac{ atoms }{ mol }\)
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
I do not know how to do this ..
 one year ago

dimensionx Group TitleBest ResponseYou've already chosen the best response.0
Sure you do ;) Let's take it step by step. You are given 1 gram of H2O, and need to divide this by the molecular weight. The molecular weight can be found by adding up all the individual masses of the atoms. How many atoms of Hydrogen are in H2O? How many atoms of Oxygen are in H2O? Multiply the number of atoms of Hydrogen by the atomic mass of hydrogen. Multiply the number of atoms of Oxygen by the atomic mass of oxygen. Add these two values together, what do you get?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
2 atoms in Hydrogen and 1 atom of Oxygen. atomic mass of hydrogen is 1 2*1=1 atomic mass of oxygen is 15.9994 15.994*1=15.9994 Added together is 16.9994
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Do you have it now? Or do you still need help?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
I don't know if 16.9994 is the answer?
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Hang on. I'll figure it out
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
Okay thank you
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
No. Obviously no. It's way too small.
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
I have no clue what I am doing
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Do you know what a mole is?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
Not really
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
That might be your trouble. A mole of any compound or element is the molecular weight in grams. So if you had a scale and wanted to weigh out a mole of water, you would weigh out 18 g because 2H=2, O = 16 and the molecular weight is 18
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Do you understand that?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
No, I am so sorry
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Do you know how to find molecular weight?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
I looked it up online
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
So I take that to be a yes?
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Do you have a periodic table?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
I looked up the weight online. and I do, yes
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Find the molecular weight of HCl
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
36.46094
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
So a mole of HCl is 36.46094 grams.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Now here is the next important point: a mole of "stuff" has 6.023 x 10^23 molecules in it.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
That's Avagadro's number. That is something you cannot reason out you have to learn it.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
So lets say I have some carbon. A mole of carbon is 12 grams. I have 24 grams. How many moles is that?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
12
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
2
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Yes. Good. Now remember each mole is 6.023 x 10^23 molecules so how many molecules of carbon do I have?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
I suppose I do not understand how 6.023 X 10^23 works because if there are 2 moles how exactly do I work that in?
 one year ago

dimensionx Group TitleBest ResponseYou've already chosen the best response.0
If you have 1 mole of "stuff", you have exactly 6.023 x 10^23 molecules. If you have 2 moles of stuff, you would multiply Avogadro's number by 2.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Would you agree that 2 moles is twice as much as 1 mole and so I should multiply by 2?
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
And \[2(6.023 \times 10^{23)}=12.046 \times 10^{23}\]
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
So that is the number of molecules in 2 moles of carbon.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Ok. dimensionx will help you now. Too many cooks.
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
so we aren't really solving the entire equation because when I did that I had a ginormous number
 one year ago

dimensionx Group TitleBest ResponseYou've already chosen the best response.0
@Mertsj sorry didn't mean to tread on you xD blahhhh, We are taking it stepbystep ;)
 one year ago

dimensionx Group TitleBest ResponseYou've already chosen the best response.0
So we know that we have 2 Hydrogens and 1 Oxygen. 2 x Hydrogen 1 x Oxygen 2 x (1) = 2 1 x (16) = 16 Total Molecular Weight = 18
 one year ago

dimensionx Group TitleBest ResponseYou've already chosen the best response.0
Do you understand how I got this value?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
yes.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
So why isn't this problem done yet?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
because I do know how to apply this... I am thinking at 18 is the answer. I am sorry It is just not clicking.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
18 grams is 1 mole of water. How many moles is 9 grams of water?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
.5
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
That would be 9/18 right?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
yes
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
How many moles is 3 grams of water?
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Just tell me the fraction.
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
50 g
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
I think I see a pattern here: I will draw it because I want you to see it too.
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
okay!
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
dw:1364947152844:dw
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Do you see the pattern?
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
How many moles is 1 g water?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
1/18
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Now we know we have 1/18 mole of water and each mole has 6.023 x 10^23 molecules. So we should multiply 1/18 by 6.023 x 10^23 to find how many molecules we have.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
What do you get?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
hang on
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
my calculator says 0
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
dw:1364947644414:dw
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
I am not getting those numbers..
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Type 6.023 divided by 18 equals
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Did you get .334611111111 ??
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
yes.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
That has to be multiplied by 10^23 but that is WAAAAAAY to many zeros so we we just write it: \[.33461111 \times 10^{23}\]
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
However we have two problems. 1. That is too many significant digits 2. It is not in scientific notation.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
So we will round it to .33 So now we have: \[.33 \times 10^{23}\]
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
But that is still not scientific notation so we will change the .33 to 3.3 but that means we have to change the exponent to 22: \[3.3 \times 10^{22}\]
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
Oh! that mas sense
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
makes*
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Excellent. Now. You can do these problems without really understanding them if you know or can find the right conversion factors and just set it up so that the units turn out right. Do you care to see that?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
Of course!
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Start with what is given: 1 g water
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
\[1 gram water \times \frac{1 mole water}{18g water} \times \frac{6.023 x 10^{23}molecules}{1 mole water}\]
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Notice how the units cancel just like numbers and you end up with the number of molecules which is just what the problem asked for.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
So if the units come out right, you know you have the numbers right.
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
so that would translate to 1 x 18/18= 1 x 6.023x10^23/18?
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
yes. multiply all the numerators and divide by all the denominators.
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
But the powers of 10...just leave that til the end.
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
when I did that I got a massive number..since I already knew it 3.3x10^22 it made sense how do I figure it out when there is no decimal?
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
The exponent 22 means move the decimal point 22 places to the right. That's why we use scientific notation. Who wants to mess with all those zeros?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
right, it is like I get it for a second then it all goes away. when I did it using the formula you gave canceling everything out I just got a massive number 334111111111...
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
33461*
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Exactly. You can enter it into your calculator if you use the EE button to enter the exponent. At least that's the way it is on my calculator. I enter 6.023 EE23 and then it manages the exponents and scientific thing for me.
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
Oh I get it! .... so when it is a .xy number you move the decimal and it becomes x.y^22 instead of ^23. and if it turns out a x.y number it stays ^23?
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
OH MY GOD YOU ARE POSITIVELY AMAZING AND YOU HAVE NO IDEA HOW MUCH I APPRECIATE YOUR TIME AND PATIENCE! In the future if I come across a problem like this I would like to run it by you so you check it? Or any other problems that threaten a brain aneurysm lol
 one year ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.3
Glad to be of service. Remember Jesus said, "Whoever would be great among you, let him be your servant."
 one year ago

blahhhhh12345678 Group TitleBest ResponseYou've already chosen the best response.0
Beautiful. I wouldn't want to call you a servant but, I love to learn from those who know more than I do.
 one year ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.