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Questions tagged [gas-laws]

Physical and chemical laws describing the properties and behavior of gases. This tag currently applies to properties and laws concerning both ideal and real gases.

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Water Gas Shift Reaction [on hold]

For the extremely important water gas shift reaction shown below, the $K_c = 3.491$ at a certain temperature. What are the equilibrium concentrations of all the components of the reaction if $\pu{0....
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1answer
354 views

Can the van der Waals coefficients be negative in the van der Waals equation for real gases?

A gas described by van der Waals equation has the pressure that is lower than the pressure exerted by the same gas behaving ideally. True or false? My approach $$P(\text{ideal}) = P(\text{real}) + P(...
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1answer
33 views

Relationship between rate of reaction and pressure

Given the equation $$\ce{A(g) + B(g) → C(g) + D(g)}$$ with reaction rate given by $$v = k[\ce{A}]^2$$ How can I prove that reaction rate goes up with pressure? I tried substituting $k$ for $Ae^{-...
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0answers
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Is (n1/v1) = (n2/v2) a valid interpretation of Avogadro's Law? [on hold]

I learned the formula for Avogadro's Law as (V1/n1) = (V2/n2) And it's one I've always used due to 22.4 L/mol conversion factor. But in the Wikipedia article and several other places, I've seen ...
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0answers
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How to derive the compressibility factor for a van der Waals gas?

So as far as I know, $$Z=\frac{p_\mathrm{r}V_\mathrm{r}}{nRT},$$ where $\mathrm{r}$ denotes the subscript for real. Solving it for a van der Waals gas gave me the following result, $$Z=1+\frac{p_\...
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2answers
62 views

Compressibility Factor Of Gases

In the general equation of the compressibility factor $Z$, we define $Z$ as $$Z=\frac{pV}{nRT}$$ Here, what is $p$? Is it $p_\text{real}$ or $p_\text{ideal}$? Also, what is $V$? $V_\text{real}$ or $V_\...
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2answers
61 views

Relationship between the ideal gas constant and entropy

So it dawned on me the other day that the ideal gas constant $$R = \pu{8.31 J mol-1 K-1}$$ has the same units as molar entropy. Is there some deeper meaning behind this or is it just a coincidence ...
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28 views

For azeotropic mixtures, is the total vapour pressure at equilibrium equal to the partial pressure of one of the components?

I know, a ridiculous statement. But here's how I reached at it . Say we have a solution of two components liquids A and B. By Raoults law, $$p_A= p_A^o \times x_A \tag1$$ Also by Dalton's law, $$...
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0answers
46 views

Pressure of Gas Collected Over Water

My textbook, as well as practically every online source I have looked into, says that when you collect gas over water, the pressure of the trapped gas plus the vapor pressure of water at that given ...
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1answer
48 views

Why 1 mole of H2 occupied the same volume occupied by 1 mole of O2?

I'm asking a question about the volume occupied by gasses in standard temperature and pressure. My textbook said that a mole of any gas occupies 22.4 L at standard temperature and pressure. But ...
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1answer
74 views

if a balloon full of warm air was placed in a refrigerator, what is the result? [closed]

If a balloon full of warm air was placed in a refrigerator, What will happen to the Ballon ?
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1answer
94 views

Are the vibrational modes of CO2 active at room temperature?

I was doing an experiment whereby I had to measure the specific heat ratios of certain gases. Carbon dioxide came out to be around 1.3, and checking with the accepted values this is close. My question ...
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0answers
61 views

Volume of dried gas at STP

A $54.0\ \mathrm{mL}$ sample of oxygen is collected over water at $20\ \mathrm{^\circ C}$ and $770\ \mathrm{Torr}$ pressure. What is the volume of the dry gas at STP? By using the combined gas law, I ...
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2answers
65 views

What will be unit of volume in V=nRT/p if p is in Torr instead of atm? [closed]

$V=nRT/p$, where $n$ is amount of gas in $\mathrm{mol}$, $R$ is gas constant, $V$ is volume in $\pu{dm3}$, and $p$ is pressure in $\pu{atm}$. What happens to $R$ if $p$ is in $\pu{Torr}$ instead of $...
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2answers
118 views

The respective speed of five molecules are 2, 1.5, 1.6, 1.6 and 1.2 km/s. The most probable speed in km/s will be?

The respective speed of five molecules are 2, 1.5, 1.6, 1.6 and 1.2 km/s. The most probable speed in km/s will be? 1. 2 2. 1.58 3. 1.6 4. 1.31 I think the answer should be 1.6 km/h but the ...
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2answers
105 views

Derivation of work done by real gas

According to the Wikipedia on real gases, it is stated that the expansion work done by a real gas differs from the ideal gas by $\int\left(V-\frac{RT}p\right)\,\mathrm dp$. Firstly, does this mean $...
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1answer
62 views

Solving a quadratic of for pressure of real gas with unknown volume

I had this question on my test: Calculate the pressure exerted (in atm) by 1 mole of $\ce{CH4}$ gas at a temperature of $\dfrac{24}{0.0821}$ K if volume occupied by $\ce{CH4}$ molecules ...
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1answer
48 views

Compressibility factor of hydrogen at low pressure and constant temperature

As we all know, the compressibility factor $Z$ of hydrogen and helium is always greater than $1$ at a constant moderate temperature. But, if we look at the virial equation of compressibility factor $$...
2
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2answers
328 views

Entropy change of isothermal irreversible expansion of ideal gas [duplicate]

Two mole of an ideal gas is subjected to isothermal expansion from $\pu{2 atm}$ to $\pu{1 atm}$ at $\pu{300 K}$. Calculate entropy change of the system, surrounding and total, if the process is ...
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1answer
44 views

Real gas equation at high molar volume

How would the van der Waals equation of state look like when molar volume of gas is high? Does high molar volume correspond to low pressure? My textbook says that A real gas behaves similar to an ...
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4answers
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How could the ideal gas law be discovered from experiments on real gases?

The gas laws, namely Boyle's Law, Charles' Law, Avogadro's Law and Gay-Lussac's Law, are all experimental laws. Combining these laws, we get the ideal gas law $pV=nRT$. Also, "real life" gases do not ...
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1answer
73 views

How to calculate the volume or mass of carbon dioxide gas absorbed by a calcium hydroxide solution?

Carbon dioxide reacts with calcium hydroxide as shown by the equation: $$\ce{Ca(OH)2 (aq) + CO2 (g) -> CaCO3 (s) + H2O (l)}$$ A solution containing $\pu{0.1 mol}$ of calcium hydroxide reacts ...
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1answer
41 views

Volume of air required to oxidize glucose

In the body, the oxidation of glucose is according to the reaction: $$\ce{C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O}$$ Knowing that glucose consumption is $\pu{2.47 mol/d}$, What is the volume of ...
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1answer
21 views

Combination of several unit symbols when finding new pressure from ideal gas law

As a car is driven, the tires heat up and the volume and the pressure change. Calculate the new pressure of a 35.0 L tire initially at 235 kPa that expands to 36.5 L when it heats up from 15.0 °C to ...
2
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1answer
64 views

How to calculate the standard Gibbs energy at equilibrium?

Given that $K_c = 1.7 \times 10^{-13}$, calculate $\Delta G^{\circ}$ for this equilibrium mixture at $\pu{298 K}$. $$\ce{N2O (g) + \frac{1}{2}O2 (g) <=> 2 NO (g)}$$ I've calculated: $$ \...
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2answers
54 views

Finding percentage of the gas in a binary gaseous mixture of the given density

At STP, the density of a gas in a vessel is $0.9002$. If the gas is a mixture of argon and helium, what percentage of the gas is argon? I am stuck on this. From what I can gather, the only ...
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4answers
74 views

Adiabatic processes and the Ideal Gas Law [closed]

in my first year chemistry textbook it wrights that in adiabatic proccess when there is a system of canister filled with gas and a piston above(and wheights on it) if we let the piston move upward by ...
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1answer
61 views

Why is excluded volume in van der Waals equation divided by 2?

Source: Physics Stack Exchange The excluded volume calculated based on the diagram is 8 times the volume of a molecule. The volume is then divided by 2 to give the so-called excluded volume per ...
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1answer
239 views

Compressibility Factor Graph - Which gas attains a deeper minimum?

As in the given graph, how do I predict which curve among that of hydrogen, methane, and carbon dioxide attains a deeper absolute minimum? (greater deviation from Z=1). In fact, how do I make this ...
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0answers
50 views

Determining mole fraction of carbon dioxide knowing Kp only

I've been assigned the following problem at school: Given the following reaction: $$\ce{C (s) + CO2 (g) <=> 2 CO (g)}$$ Find the mole fraction of $\ce{CO2}$ provided that, in ...
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1answer
71 views

What is the radius of the atoms? [closed]

In a recipient there is an unknown monoatomic gas that occupies a volume of $\pu{230 cm3}$, at $\pu{300 K}$ and $\pu{1 atm}$. It is known that the atoms occupy a volume of $2\times10^{-4}$. Find the ...
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1answer
95 views

What is the temperature dependency of the van-der-Waals constants? [closed]

What is the effect of the temperature on the van-der-Waals constants $a$ and $b$? I have checked on the effect of pressure and volume on the van-der-Waals constants, but I've not been able to get the ...
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1answer
56 views

Equilibrium constant from mole ratio

Chapter 4, problem 13 from the Chemical Priciples [1, p. 170]: Equilibrium concentrations Experiments have shown that at $\pu{60 °C}$ and $\pu{1 atm}$ total pressure, the equilibrium ratio of $...
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1answer
66 views

Calculating volume of gases in different conditions

Doctor Who has a secret laboratory on Venus where atmospheric pressure is $92$ times that of Earth and room temperature is $\pu{735 K}$. There, Doctor Who mixes $\pu{4.00 g}$ of $\ce{CaCO3}$ with $\pu{...
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1answer
114 views

Calculating enthalpy change for a real gas

I know this question would be closed citing it to be a homework question. I posted it earlier also. But believe me I have tried it for myself before and that too many times but then couldn't arrive at ...
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1answer
96 views

How does a gas occupy a fixed molar volume?

It is common knowledge that one mole of ideal gas occupies a volume of 22.41 L at standard temperature and pressure (0°C and 1 atm). However, this goes against the claim that gases don't have a fixed ...
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1answer
25 views

Why is STP mol/liter so specific? [duplicate]

How do we know that one mole of an ideal gas occupies (exactly) 22.4 Liters? Why is it so precise a value? Many other constants/conversions in science have multiple decimal places, so why is this ...
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2answers
137 views

Why do Gas Laws only use Kelvin Temperature? [closed]

I didn't see this in any other question, although it seems to be a fundamental question of the gas laws. I understand that Charles' Law practically has to use Kelvin temperature, because you would end ...
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1answer
130 views

What does the volume of a gas depend on?

In my chemistry textbook, it states that the volume of a gas is directly proportional with the amount(number of moles) of that gas. However, it also mentioned before that the volume of a gas depends ...
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1answer
468 views

If temperature and volume are same, the pressure of gas obeying van der Waal's equation is smaller than that of an ideal gas"

Can you state the reasons for it. I think " It is smaller because mutual forces of attraction would resist the collision of particle and container".
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1answer
106 views

Can ideal gas law be applied to water vapour? [closed]

How to accurately estimate the molar concentration of pure water vapour at 298 K? Can ideal gas law be applied to water vapour to calculate the molar concentration?
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2answers
74 views

What's wrong with this gas law problem?

I recently took a chemistry test in which the following problem was offered: a 137 mL gas sample is collected over $H_2O$ at 753 mmHg and $22^oC$. What is the volume of the dry gas at STP if the ...
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Feasibility of application of Boyle's law in the case of varying number of moles [closed]

While reading up on ideal gases and the Boyle's law, I encountered a question in my textbook wherein a balloon was being filled with helium (assumed to be ideal) till it was just about to burst. The ...
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1answer
90 views

Equalizing Pressure Question

I have a question about the gas collection over water lab: We learned that when the water level inside the graduated cylinder is higher than the outside water level, the gases inside the graduated ...
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1answer
78 views

Calorific value of a gas in combustion

The Wikipedia article on heat of combustion says: The calorific value [...] may be expressed with the quantities: energy/mole of fuel energy/mass of fuel energy/volume of the fuel ...
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0answers
52 views

Comparing pressure and volumes of ideal and real gas

This question has been troubling me for quite a while now. Which has greater pressure: Real gas or an ideal gas under similar conditions? What about their volumes? I read this in many sources and ...
2
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1answer
121 views

Why do gases coexist as liquid and vapour?

I have having difficulty in understanding the liquefaction of gases.In the graph of isotherms of $\ce{CO2}$ I cannot understand how can gas coexist as liquid and vapour under area of $\mathrm{XCEBY}$....
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1answer
43 views

Why are moles used in the ideal gas law and not simply mass?

The crux of my question is, why is just the amount of particles included in $PV=nRT$ and there is nothing to account for the mass of the individual molecules? Or is mass accounted for in temperature, ...
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1answer
115 views

Interpreting straight lines in a graph of isotherms of carbon dioxide

I am having difficulty in understanding pressure-volume graphs of $\ce{CO2}$ at different temperatures which describes liquefaction of $\ce{CO2}$. I know that at the critical temperature of $\pu{31.1^...
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3answers
345 views

What is the term used as correction for attractive forces in the Van der Waals Equation?

I have seen a question in my textbook which is little bit confusing, The term that corrects for attractive forces present in real gas in van der Waal equation is (i) ${nb}$ (ii) $\frac{an^2}...