Help => Chemistry Ideal Gas Constant! HELP 10 POINTS!! Best Answer!?

PV = nRT

where P is pressure in atm

V is volume in liters

n is # of moles

R is the gas constant

T is temperature in Kelvin (add 273 to celcius)

#1

(1.3 atm)(0.482 L) = n(0.0821)(310K)

divide both sides by (0.0821)(310)

n = (1.3)(0.482) / (0.0821)(310)

n = 0.0246198578 moles

2.46 x 10^-2 moles

or D

A and B should be disregarded immediately because they're not in scientific notation

#2

To get atm from torr divide your measured torr over 760 (1 atm)

782/760 torr = 1.0289473684 atm

Same deal as before

(1.0289473684 atm)(2.4 L) = n(0.0821)(298 K)

Although it's sort of unnecessary because a is the only answer in scientific notation

n=(1.0289473684)(2.4) / (0.0821)(298)

n = 0.1009357423 moles

or A

#3

Charles's law (temperature changes are proportional to volume changes)

v1/t1 = v2/t2

0.25 L(273 K) = (v2)(308 K)

v2 = 0.2217126623 L

A (typo?)

#4

0.5 moles / 0.1 moles (2.0 L) = 10 L

Given 482 milliliters of a gas at 37 degrees Celsius and at 1.3 atmospheres, how many moles of gas are present? (The ideal gas constant is 0.0821 L · atm/mol · K.)You must obviously know the gas equation:

PV = nRT

When using this equation you have to get the units correct .

P = pressure = 1.3atm

V = volume = 482mL = 0.482L

n = moles - what you want

R = constant - you are given 0.0821

T = temp in K = 37+273 = 310

Substitute intro the equation:

1.3*0.482 = n * 0.0821*310

n = (1.3*0.482) /(0.0821*310)

n = 0.6266 / 25.45

n = 0.0246 = 2.46*10^-2 moles Answer d) is correct

2) Given 2.4 liters of a gas at 25 degrees Celsius and at 782 torr, how many moles of gas are present? (The ideal gas constant is 0.0821 L · atm/mol · K and 1 atm = 760 torr.)

P = 782/760 = 1.029 atm

V = 2.4

n= ???

R = 0.0821

T = 298

1.029*2.4 = n*0.0821*298

n = (1.029*2.4) / (0.0821*298)

n = 2.469/24.47

n = 0.101 mol = 1.01*10^-1 Answer A is correct

3) A cylinder with a movable piston contains a fixed amount of gas at a constant pressure. Initially, the cylinder contains 0.25 liters of air at 0 (zero) degrees Celsius. When the temperature is increased to 35 degrees Celsius, the air will occupy what volume?

The simplest way to do these question - which deal only with changes in volume / pressure / temperature ( there is no gas quantity to worry about) is to use the combined gas equation . If something is constant , omit it: ( temperature must be in K)

V1/T1 = V2/T2

0.25/273 = V2/ 308

V2 = 0.25*308/273

V2 = 0.28L answer a) is correct

4)A balloon containing 0.10 moles of gas has a volume of 2.0 liters. If temperature and pressure remain constant, what will be the new volume when 0.40 moles of gas are added to the balloon?

You are increasing the amount of gas from 0.10mol to 0.5mol - that is the final quantity is 5 times initial quantity . Therefore at constant temperature and pressure, the volume will be 5 times the initial volume

Volume = 2*5 = 10L Answer d) is correct.

I won't give you all the answers, but I will help you.

The equation in this case is PV=nRT.

P=Pressure

V=Volume

n=moles of gas

R=Ideal gas constant

T=Temperature

For pressure, remember 1 atmosphere = 760 torr = 760 mmhg = 101.3 kPa for conversion purposes. keeps things in atmospheres for this equation.

If you want to solve one of these, set it up like so. First, try to find one side, then set it equal to the other side and divide by the unknown. I'll show you the first one.

Given 482 milliliters of a gas at 37 degrees Celsius and at 1.3 atmospheres, how many moles of gas are present? (The ideal gas constant is 0.0821 L · atm/mol · K.)

Alright, so first, lets look at a problem. The temperature is 37 degrees Celsius. That just isn't going to work. you have to convert it to kelvins. Just add 273. That's all. So your new temperature is 310 k.

The next problem is that 482 milliliters. You need to put that to Liters. To do that, remember KHDUDCM. Just move the decimal place over three times, so your new volume is 0.482 (remember significant digits).

All of the other units are right. You can not go about setting up the equation:

(1.3 atm) x (0.482) = n x (0.0821 L · atm/mol · K) x (310k)

So on the left side, you get 0.6266. That means the right side of the equation together must equal that number. This makes the job really easy. On the right side, so far, we have 25.451.

0.6266 = n x 25.451

n = 0.6266 / 25.451 (Because the n is on the right side, you put the left number on top)

n=0.02461

So I got...

0.6266 = 0.6263

Which is not exact, but close enough. I guess it would have to be answer choice D.

(1) Given 482 milliliters of a gas at 37 degrees Celsius and at 1.3 atmospheres, how many moles of gas are present? (The ideal gas constant is 0.0821 L · atm/mol · K.)

PV = nRT

n = (PV)/RT)

n = ((1.3 atm)*((482/1000) L))/((0.0821 L atm mol^-1 K^-1))*(37+273.15))

n = 0.0246 = 2.46x10^-2 mol

This is answer (d)

(2) Given 2.4 liters of a gas at 25 degrees Celsius and at 782 torr, how many moles of gas are present? (The ideal gas constant is 0.0821 L · atm/mol · K and 1 atm = 760 torr.)

PV = nRT

n = (PV)/RT)

n = (((782/760) Torr)*((2.4 L))/((0.0821 L atm mol^-1 K^-1))*(25+273.15))

n = 0.1009 = 1.01x10^-1 mol

This is answer (a).

(3) A cylinder with a movable piston contains a fixed amount of gas at a constant pressure. Initially, the cylinder contains 0.25 liters of air at 0 (zero) degrees Celsius. When the temperature is increased to 35 degrees Celsius, the air will occupy what volume?

We set this up slightly differently. P and n are constants in this problem.

PV1 = nRT1

V1/T1 = nR/P

PV2 = nRT2

V2/T2 = nR/P

nRP is the same for both, so we can equate the two:

V1/T1 = V2/T2

V1 = 0.25 L

T1 = 0 °C = (0 + 273.15) = 273.15 K

V2 = unknown

T2 = 35 °C = (35 + 273.15) = 308.15 K

Now plug in the values and calculate V2:

V2 = (V1*T2)/T1

V2 = ((0.25 L)*(308.15 K))/(273.15 K) = 0.28 L

This is answer (a)

(4) A balloon containing 0.10 moles of gas has a volume of 2.0 liters. If temperature and pressure remain constant, what will be the new volume when 0.40 moles of gas are added to the balloon?

As in (3), we set this up slightly differently. P and T are constants in this problem.

PV1 = n1RT

n1/V1 = P/(RT)

PV2 = n2RT

n2/V2 = P/(RT)

P/(RT) is the same for both, so again we equate the two:

n1/V1 = n2/V2

n1 = 0.10 mol

V1 = 2.0 L

n2 = (0.10 + 0.40) = 0.50 mol

V2 = unknown

Now plug in and calculate

V2 = (n2*V1)/(n1)

V2 = ((0.50 mol)*(2.0 L))/(0.10 mol) = 10 L

This is answer (d)

do you advise you decide on solutions in straight forward terms? a million) C 2) develop. this would be a undesirable question. not solid. 3) you have the equation, you do the mathematics. don't be lazy. 4) i think of is B. I long forgo my chemistry and physics. and you need to quite learn.