Tag: gas laws

Questions Related to gas laws

Chlorofluorocarbons such as $CCl _3F\ (M=137.5)$ and $CCl _2F _2\ (M=121)$ have been linked to ozone depletion in Antarctica. As of $2004$, these gases were found in $275$ and $605$ parts per trillion $(10^{12})$, ny volume. What are the concentrations of these gases under conditions typical of Antarctica stratosphere ($200\ K$ and $0.08\ atm$)? $(R=0.08\ l-atm/K-mol)$   

chemistry states of matter: gaseous and liquid states gay lussac's law gas laws states of matter

  1. $[CCl _3F]=1.375\times 10^{-12}\ mol\ l^{-1}$,
    $[CCl _2F _2]=3.025\times 10^{-12}\ mol\ l^{-1}$

  2. $[CCl _3F]=2.75\times 10^{-14}\ mol\ l^{-1}$,
    $[CCl _2F _2]=6.05\times 10^{-14}\ mol\ l^{-1}$

  3. $[CCl _3F]=2.75\times 10^{-10}\ mol\ l^{-1}$,
    $[CCl _2F _2]=6.05\times 10^{-10}\ mol\ l^{-1}$

  4. $[CCl _3F]=1.375\times 10^{-13}\ mol\ l^{-1}$,
    $[CCl _2F _2]=3.025\times 10^{-12}\ mol\ l^{-1}$

Show answer
Correct Option: A
Explanation:

$CCl _3F(mw)=133.5$
$CCl _2F _2(mw)=121$
By given data first we calculate density of solution
$\dfrac {P}{S}=\dfrac {RT}{Mw}\quad R=0.08\quad T=200$
$P=0.08$
for $CCl _3F-S(CCl _3F)=\dfrac {0.08\times 133.5}{0.08\times 200}$
$S=0.6875$
for $CCl _2F _2=\dfrac {0.08\times 121}{0.08\times 200}$
$=0.605$
given data in $(PPt)$
$10^{12}\ gm$ solution contains $=175\ gm$
$10^{3}\ gm$ solution contains $=\dfrac {275}{10^{12}}\times 10^3$
Mass $=275\times 10^{-9}\ gm$
find the volume $d=\dfrac {M}{v}$
$v=\dfrac {1000}{0.6785}=1454.5$
Molarity of $CCl _3F=\dfrac {275\times 10^{-9}}{137.5\times 1454.5}$
$=1.37\times 10^{-12}$
Similarly for $CCl _2F _2$
$10^{12}\ gm$ solution certain $=605$
$10^{3}\ gm$ solution certain $=\dfrac {605}{10^{12}}\times 10^3$
Mass $=605\times 10^{-9}$
$d=\dfrac {m}{v}\quad v=\dfrac {m}{v}=\dfrac {1000}{605}$
$v=1652.89$
molarity $=\dfrac {605\times 10^{-9}}{121\times 1652.89}$
$M=3.02\times 10^{-12}\ mol\ l^3$

A quantity of $4$g of oxygen occupies $10$ L at a particular pressure and temperature. If the pressure of gas is doubled and absolute temperature is halved, in order to maintain constant volume.

chemistry states of matter: gaseous and liquid states gay lussac's law gas laws states of matter

  1. $3$ g gas should be removed from container

  2. $3$ g gas should be added in the container

  3. $16$ g gas should be added in the container

  4. $12$ g gas should be added in the container

Show answer
Correct Option: D
Explanation:

Given that,
$m _1=4g$ $V _1=10L$,$P _1=P$,$T _1=T$

$m _2=?$, $V _2=10L$,$P _2=2P$, $T _2=\dfrac{T}{2}$

We know that,

$PV=\dfrac{m}{M}RT$

At constant volume, V

$\dfrac{P _1}{P _2}=\dfrac{m _1RT _1}{m _2RT _2}$

$\dfrac{P}{2P}=\dfrac{4\times T}{m _2\times \dfrac{T}{2}}$


$\dfrac{1}{2}=\dfrac{8}{m _2}$

$m _2=16$g

Mass of gas added into container$=16-4=12$g.

In the reaction $N _{2}+3H _{2}\rightarrow 2NH _{3} $, the ratio by volume of $N _{2},\ H _{2} :$ and$: NH _{3}$ is $1 : 3 : 2$. 


This illustrates the law of:

chemistry states of matter: gaseous and liquid states gay lussac's law gas laws states of matter

  1. definite proportion

  2. multiple proportion

  3. reciprocal proportion

  4. gaseous volumes

Show answer
Correct Option: D
Explanation:

In the reaction, $N _{2}+3H _{2}\rightarrow 2NH _{3} $, the ratio by volume of $N _{2},\ H _{2} $ and $ NH _{3}$ is $1 : 3 : 2$. This illustrates the law of Gaseous volumes or Gay Lussac's law of combining volumes of gases.

According to this law, when gases react together to produce gaseous products, the volume of reactants and products bear a simple whole-number ratio with each other, provided volumes are measured at the same temperature and pressure.

So, the correct option is $D$.

To use Gay-Lussac's Law, which of the following needs to remain constant?

chemistry states of matter: gaseous and liquid states gay lussac's law gas laws states of matter

  1. Volume and the number of moles of a gas

  2. Pressure and temperature

  3. Temperature and the number of moles of a gas

  4. Pressure and the number of moles of a gas

  5. Temperature and volume

Show answer
Correct Option: A
Explanation:

$P \propto T $
At constant volume and number of moles of a gas, the pressure is directly proportional to the absolute temperature.

Hence, option $A$ is correct.

A closed vessel contains equal number of nitrogen and oxygen molecules at a pressure of $p\ mm$. If nitrogen is removed from the system then the pressure will be:

chemistry states of matter: gaseous and liquid states gay lussac's law gas laws states of matter

  1. $p$

  2. $2p$

  3. $p/2$

  4. $p^2$

Show answer
Correct Option: C
Explanation:
At constant $V, P\propto n$

$\therefore$ if no. of moles is halved then pressure will also reduce to $p/2$.

Option C is correct.