October 02, 2023, 01:36:16 PM
Forum Rules: Read This Before Posting

### Topic: Molar Volume of Gasas Problem , HELP asap  (Read 16990 times)

0 Members and 1 Guest are viewing this topic.

#### ChenistryNoob1

• New Member
• Posts: 4
• Mole Snacks: +1/-0
##### Molar Volume of Gasas Problem , HELP asap
« on: October 23, 2015, 11:44:20 AM »
I have ; Calculate the volume of Hydrogen gas produced at STP when 5g of Magnesium react with Hydrochloric Acid?

I made the balance equation but I think im messsing with anohter method . Any help?

#### mikasaur

• Full Member
• Posts: 235
• Mole Snacks: +27/-1
• Gender:
• Chemist in training
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #1 on: October 23, 2015, 12:08:55 PM »
A balanced equation is an excellent place to start. Why not write it out here and start to work through the problem. Then we can help you make progress.
Or you could, you know, Google it.

#### ChennistryNewbie

• Regular Member
• Posts: 29
• Mole Snacks: +0/-3
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #2 on: October 23, 2015, 12:21:35 PM »
Im the same guy but from anohther pc account lol
Mg (s) + 2 HCl (aq) --> MgCl 2 (aq) + H 2

I wrote 5g under Mg and under H2 a ?

#### Arkcon

• Retired Staff
• Sr. Member
• Posts: 7367
• Mole Snacks: +533/-147
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #3 on: October 23, 2015, 12:35:42 PM »
Ok, now, you have a balanced equation.  What are it's units? You can use it to relate a certain "amount" of magnesium to a certain "amount" of H2.  How will you do that?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

#### ChennistryNewbie

• Regular Member
• Posts: 29
• Mole Snacks: +0/-3
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #4 on: October 23, 2015, 12:38:37 PM »
its grams i guess

#### Arkcon

• Retired Staff
• Sr. Member
• Posts: 7367
• Mole Snacks: +533/-147
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #5 on: October 23, 2015, 12:43:43 PM »
No.  It's not.

Quote
Mg (s) + 2 HCl (aq) --> MgCl2 (aq) + H2

You don't go to a shelf, and pick up a magnesium atom, and squish it together with 2 HCl molecules, so what are the units in this case.

Yes, you are given magnesium in grams, and you are asked for volume of gas, but you will have to convert from ...?
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

#### ChennistryNewbie

• Regular Member
• Posts: 29
• Mole Snacks: +0/-3
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #6 on: October 23, 2015, 12:47:36 PM »
I m not understanding

#### mikasaur

• Full Member
• Posts: 235
• Mole Snacks: +27/-1
• Gender:
• Chemist in training
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #7 on: October 23, 2015, 12:58:57 PM »
The chemical equation has implied units. You're taking a certain "amount" of "stuff" and turning it into a different "amount" of "stuff".

It's not grams. Can you see why it's not grams? If it were grams then how much H2 would you expect to make from 1000g of Mg? Would that amount of H2 make intuitive sense?
Or you could, you know, Google it.

#### ChennistryNewbie

• Regular Member
• Posts: 29
• Mole Snacks: +0/-3
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #8 on: October 23, 2015, 01:01:29 PM »
No it wouldnt make sense as its a big number , can you give me the correct equation then?

#### mikasaur

• Full Member
• Posts: 235
• Mole Snacks: +27/-1
• Gender:
• Chemist in training
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #9 on: October 23, 2015, 01:21:27 PM »
The equation is correct. But you're thinking about the units wrong. Your equation says that for every unit of Mg consumed you're producing one unit of H2. It's not grams. What is that unit?

PS I just noticed the title of your post. Please read up on the forum rules here: http://www.chemicalforums.com/index.php?topic=65859.0

Specifically asking for help -- especially urgently -- goes against the forum guidelines.
Or you could, you know, Google it.

#### ChennistryNewbie

• Regular Member
• Posts: 29
• Mole Snacks: +0/-3
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #10 on: October 23, 2015, 01:33:27 PM »
I dont know :/ , + the units is used at the end after the answer . the units come at last place .. is it 1mole of Mg = 1 mole of H2 ? I need to get this solved
« Last Edit: October 25, 2015, 12:27:59 PM by Arkcon »

#### mikasaur

• Full Member
• Posts: 235
• Mole Snacks: +27/-1
• Gender:
• Chemist in training
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #11 on: October 23, 2015, 01:41:01 PM »
is it 1mole of Mg = 1 mole of H2 ?

Yes. It's moles. So now that you know that, how many moles of Mg do you start with? How many moles of H2 do you produce? How do you convert that to a volume?
Or you could, you know, Google it.

#### ChennistryNewbie

• Regular Member
• Posts: 29
• Mole Snacks: +0/-3
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #12 on: October 23, 2015, 01:47:24 PM »
as I wrote 1mole of Mg = 1 mole of H2 ,,,,, its 1 becuz on the equation there isnt any numbers of the balancing. Now i write the RMM of both?

#### ChennistryNewbie

• Regular Member
• Posts: 29
• Mole Snacks: +0/-3
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #13 on: October 23, 2015, 02:06:05 PM »
Can you work out this one for me? As I have 12 others like this

#### mikasaur

• Full Member
• Posts: 235
• Mole Snacks: +27/-1
• Gender:
• Chemist in training
##### Re: Molar Volume of Gasas Problem , HELP asap
« Reply #14 on: October 23, 2015, 02:17:13 PM »
I've already told you to read the forum rules and you have obviously not, or else you would not be asking me to solve the question for you. Please read the forum rules; they're what keep this place nice and organized and what allow the members to help each other.

I'm being patient and trying to work through the problem with you. Perhaps the real issue is that you have not given yourself enough time to complete your assignment.

That said, you have correctly written the chemical equation and identified that it works in units of moles. But your problem has given you a starting amount of Mg in grams. So you'll have to convert grams to moles.
Or you could, you know, Google it.