Need Help with Neon Gas Volume and Temperature Problems?

[geek2012]

Physics Homework Help! Please!

I have homework due ASAP! Please help, I'm clueless on where to even start !


1. A sample of neon gas has its volume tripled and its temperature held constant. What will be the new pressure relative to the initial pressure?

2. A fire breaks out and increases the Kelvin temperature of a cylinder of compressed gas by a factor of 3.0. What is the final pressure of the gas relative to its initial pressure?

3. If a quantity of gas in a piston cylinder has a volume of 0.501 m3 and is initially at room temperature (20°C) and is heated in an isobaric (constant-pressure) process, what will be the temperature of the gas in degrees Celsius when it has expanded to a volume of 0.706 m3?

 

[DaveC426913]

We do not spoonfeed homework here. You must show your attempts at a solution before anyone can help you.

It is in the rules that you read when you signed up.

These are basic applications of the Gas Laws. Look them up in your book to see which ones apply.

 

[geek2012]

Well, let's start with this one...A sample of neon gas has its volume tripled and its temperature held constant. What will be the new pressure relative to the initial pressure?

I don't even know where to begin because I don't have the amount of neon gas, the original temp or volume, so I don't know how to even plug it in the equation...i know it's p1/p2=(t2/t1)(v1/v2)

 

[DaveC426913]

Well, let's start with this one...A sample of neon gas has its volume tripled and its temperature held constant. What will be the new pressure relative to the initial pressure?

I don't even know where to begin because I don't have the amount of neon gas, the original temp or volume, so I don't know how to even plug it in the equation...i know it's p1/p2=(t2/t1)(v1/v2)

What law is applicable? Look at what variable(s) you are given and what you are trying to solve for.

You are not being asked for numbers, you are being asked for a final value relative to the initial value. i.e. algebraically. If v2 triples, what happens to p2?

 

[geek2012]

well the 1st law is finding heat, so I don't need that one. the second law is inability for heat to flow from cold to hot body, and the third law of thermodynamics says that it is impossible to get a temp of absolute zero, but i don't know what my temp is. I don't know which one is applicable.

I'm a total beginner to this stuff. I apologize. I could really use all the help I can get.

 

[geek2012]

if v2 triples, then wouldn't the p2 triple as well?

 

[DaveC426913]

well the 1st law is finding heat, so I don't need that one. the second law is inability for heat to flow from cold to hot body, and the third law of thermodynamics says that it is impossible to get a temp of absolute zero, but i don't know what my temp is. I don't know which one is applicable.

I'm a total beginner to this stuff. I apologize. I could really use all the help I can get.

(You're looking at the laws of thermodynamics. You need to be looking at the Gas Laws. http://en.wikipedia.org/wiki/Gas_laws)

 

[DaveC426913]

if v2 triples, then wouldn't the p2 triple as well?

Show your work.

 

[geek2012]

okay, so using that formula, how would I go about solving it?

p1/p2=(t2/t1)(v1/v2)

I'm solving for p1/p2...so my t2/t1 would be ?? I don't have a temp...

and volume is tripled but I don't have an intial volume...


I figured that if v2 is tripled, then p2 would be tripled as well, I entered in 3 as the answer, but it was wrong.

 

[DaveC426913]

p1/p2=(t2/t1)(v1/v2)

I'm solving for p1/p2...so my t2/t1 would be ?? I don't have a temp...

1] Temp doesn't change. That means t1=t2. Unless t is zero, t1/t2 will always equal 1. If it's 1 then it drops out of the equation. Do you see why intuitively? If a property doesn't change between time a and time b, then that property is not involved in the equation. So drop it.

Now what is your equation?

 

[geek2012]

so it would now be p1/p2=v1/v2 ??

 

[DaveC426913]

Wait a minute. I wasn't paying attention. Where did you get that formula?

Does your book cover Boyle's Law and Charles' Law and the other gas laws?

 

[geek2012]

it was p1/p2=(t2/t1)(v1/v2).
you told me that if a property doesn't change, it equals one and drops out of the equation, so that would leave me p1/p2=v1/v2, correct?

 

[DaveC426913]

it was p1/p2=(t2/t1)(v1/v2).

Where did you get this formula?

 

[geek2012]

oops...sorry... p2/p1=v1/v2

is that right?

 

[DaveC426913]

oops...sorry... p2/p1=v1/v2

is that right?

It is usually expressed as v1*p1 = v2*p2, but yours will work.

So, what happens to p2 if v2 is triple the value of v1?

Start with your formula. For all initial values, use 1. You're given v2, so what's p2 going to have to be? Show your work.

 

[geek2012]

so boyle's law has that equation you had...the v1*p1=v2*p2, and if you triple v2, then it would triple the intial pressure. is that right?

 

[DaveC426913]

so boyle's law has that equation you had...the v1*p1=v2*p2, and if you triple v2, then it would triple the intial pressure. is that right?

Stop guessing and show your work.

Assume initial values p and v are 1. You're given v2.

 

[geek2012]

i don't know how to even begin to show my work.

you said v1*p1=v2*p2

if v2 is triple of v1, then p2 is triple of p1...so, I'm going to make a wild guess here...

v1*p1=3*3

I put 3 times 3, because it's tripled on each one. If this isn't correct, then I have no idea what to do. LOL

 

[DaveC426913]

i don't know how to even begin to show my work.

you said v1*p1=v2*p2

if v2 is triple of v1, then p2 is triple of p1...so, I'm going to make a wild guess here...

v1*p1=3*3

I put 3 times 3, because it's tripled on each one. If this isn't correct, then I have no idea what to do. LOL

What grade are you in? Do you know how to write out and solve an equation?

Start with the formula, substitute in your numbers, and then solve.

v1*p1=v2*p2

So

(1)*(1)=(3)*p2

What must p2 be for the left side to equal the right side?

p2=...

 

[geek2012]

I'm in college. I have never had a decent math teacher in my life. I have no idea how to do this at all. My physics professor didn't even go over the gas laws, he just came in expecting us to know how to do this.

3 times its reciprocal equals one...so 1/3?

1*1=3*1/3

 

[DaveC426913]

3 times its reciprocal equals one...so 1/3?

Does that make sense? Does it seem right? If the volume of a closed container were tripled (without changing the amount of gas in the container), should that cause the pressure in the container to drop to a third?

It is now my bedtime but you have all the tools you need to solve the other two questions on your own.

Use the same formula (make sure it is correct!)

Write it down.
Then substitute in any numbers you can. Assume any initial values are 1.
Properties that don't change can drop out of the equation (in part A that was temp, it wil be different in the other questions).
Add in the given final value (it was v2 but it will be different).
You will discover you can enter all values except a missing one (was p2), the one you are solving for.
Then pick a value for the missing number that will make the left side of the equation equal the right side.

And write down down. Don't guess.

 

[geek2012]

Yes, thank you so much for your help :)

 

[DaveC426913]

np

Try the other two. If you run into trouble, there are people who stay up later than me.