Q: In terms of Charles' law, explain why - 273 \$\displaystyle ^{\circ}C\$ is the lowest possible temperature.

At \$0 \ K\$ or \$\displaystyle -273^oC \$, the volume of the gas becomes equal to zero . The gas ceases to exists. Hence, \$\displaystyle -273^oC\$ is the lowest possible temperature.

Q: \$1\$ mole of \$H_2SO_4\$ is mixed with \$2\$ moles of NaOH. The heat evolved will be:

\${H}_{2}S{O}_{4} + 2 NaOH \longrightarrow {Na}_{2}S{O}_{4} + 2 {H}_{2}O\$According to reaction,\$1\$ mole \${H}_{2}S{O}_{4}\$ completely neutralised by \$2\$ mole of \$NaOH\$.As we know,Gram equivalent \$=\$ no. of moles \$\times\$ Valency factorValency factor of \${H}_{2}S{O}_{4} = 2\$Therefore,Gram equivalent of \${H}_{2}S{O}_{4} = 1 \times 2 = 2\$As we know,Heat evolved in the neutralisation of \$1\$ gm eq. of strong acid \$= 57.3 \; kJ\$Heat evolved in neutralisation of \$2\$ gm eq. of strong acid \$= \left( 57.3 \times 2 \right) kJ\$Hence the heat evolved will be \$2 \times 57.3 \; kJ\$.Hence, the correct option is \$\text{B}\$

Q: The value of absolute zero temperature in Fahrenheit scale is

Absolute temperature in Celsius is \$-273.15{{\,}^{o}}C\$ \$ F=\dfrac{9}{5}C+32 \$ \$ F=\dfrac{9}{5}\times (-273.15)+32=-459.67{{\,}^{o}}F \$ \$ F\cong -460{{\,}^{o}}F \$ Hence, absolute temperature in Fahrenheit

Q: For the reaction : \$2A(g)+3B\longrightarrow 4C(G) _D (l); \Delta H-=-20 kJ/mole\$Find the heat evolved when \$0.4\$ mole of A reacts with an excess of B in a closed rigid container. The temperature is constant at \$300 K\$. [R=8.3 J/K mole]

\$2 {A}_{\left( g \right)} + 3 {B}_{\left( g \right)} \longrightarrow 4 {C}_{\left( g \right)} + {D}_{\left( l \right)}\$No. of moles of A \$= 0.4\$No. of moles of C when \$2\$ moles of A reacts \$= 4 \text{ moles}\$No. of moles of C when \$0.4\$ moles of A reacts \$= 0.8 \text{ moles}\$No. of moles of B \$= 3\$ (As B is in excess)Total moles of reactant \$= 0.4 + 3 = 3.4\$Total moles of product \$= 0.8\$\${\Delta{n}}_{g} = {n}_{P} - {n}_{R} = 0.8 - 3.8 = -3\$\$\Delta{H} = -20 \; {KJ}/{mol}= -20000\; {J}/{mol}\$Temperature \$\left( T \right) = 300 K\$\$\Delta{H} = {q}_{V} + {\Delta{n}}_{g}RT\$\$\Rightarrow {q}_{V} = \Delta{H} - {\Delta{n}}_{g} RT\$\$\Rightarrow {q}_{V} = -20000 - \left( -3 \times 8.3 \times 300 \right) = -20000 + 7470 = -12530 \; {J}/{mol} = -12.53 \; {KJ}/{mol}\$Hence the required answer is \$-12.53 \; {KJ}/{mol}\$.

Question 1

In terms of Charles' law, explain why - 273 $\displaystyle ^{\circ}C$ is the lowest possible temperature.

Accepted Answer

At $0 \ K$ or $\displaystyle -273^oC $, the volume of the gas becomes equal to zero . The gas ceases to exists. Hence, $\displaystyle -273^oC$ is the lowest possible temperature.

Question 2

A circular metal loop is heated at point $O$ as shown in above Figure.
i) In which direction would heat flow in the loop?
ii) In which order the pins at points P, Q and R fixed with the help of wax fall if points O, P, Q and R are equidistant from each other?

Accepted Answer

According to the given condition.i) The heat will flow in the direction from O to P and O to R.ii) Firstly the pins at R and P will fail concurrently followed by the pin at Q.

Question 3

$1$ mole of $H_2SO_4$ is mixed with $2$ moles of NaOH. The heat evolved will be:

Accepted Answer

${H}_{2}S{O}_{4} + 2 NaOH \longrightarrow {Na}_{2}S{O}_{4} + 2 {H}_{2}O$According to reaction,$1$ mole ${H}_{2}S{O}_{4}$ completely neutralised by $2$ mole of $NaOH$.As we know,Gram equivalent $=$ no. of moles $\times$ Valency factorValency factor of ${H}_{2}S{O}_{4} = 2$Therefore,Gram equivalent of ${H}_{2}S{O}_{4} = 1 \times 2 = 2$As we know,Heat evolved in the neutralisation of $1$ gm eq. of strong acid $= 57.3 \; kJ$Heat evolved in neutralisation of $2$ gm eq. of strong acid $= \left( 57.3 \times 2 \right) kJ$Hence the heat evolved will be $2 \times 57.3 \; kJ$.Hence, the correct option is $\text{B}$

Question 4

The value of absolute zero temperature in Fahrenheit scale is

Accepted Answer

Absolute temperature in Celsius is $-273.15{{\,}^{o}}C$&#10;&#10;$ F=\dfrac{9}{5}C+32 $&#10;&#10;$ F=\dfrac{9}{5}\times (-273.15)+32=-459.67{{\,}^{o}}F $&#10;&#10;$ F\cong -460{{\,}^{o}}F $&#10;&#10;Hence, absolute temperature in Fahrenheit

Question 5

When two bodies at different temperatures are placed in thermal contact with each other, heat flows from the body at a higher temperature until they both acquire the same temperature. Assuming that there is no loss of heat to the surroundings, then:

Accepted Answer

Heat is a form of energy that gets transferred from one medium or object to another medium/object. Suppose if we a colder body and a hotter body and if it brought in contact, the heat gets transferred from the hotter body to colder body until the system of hotter & colder attains equilibrium.When two bodies at different temperatures are placed in thermal contact with each other, heat flows from the body at a higher temperature until they both acquire the same temperature. Assuming that there is no loss of heat to the surroundings, then The heat lost by the hotter body will be equal to the heat gained by the colder body.option D is correct

Question 6

Figure shows two flasks connected to each other. The volume of the flask 1 is twice that of flask 2. The system is filled with an ideal gas at temperature 100 K and 200 K respectively in the flasks. If the mass of the gas in 1 m, then what is the mass of the gas in flask 2 in equilibrium?

Accepted Answer

At equilibrium  pressure in both the flasks must be same.Using ideal gas equation;$\dfrac { { n }_{ 1 }R{ T }_{ 1 } }{ { V }_{ 1 } } =\dfrac { { n }_{ 2 }{ RT }_{ 2 } }{ { V }_{ 2 } } $$\dfrac { { m }_{ 1 }\times100K }{ { 2V }_{ 2 } } =\dfrac { { m }_{ 2 }\times200K }{ { V }_{ 2 } } $${ m }_{ 2 }=\dfrac { m }{ 4 } $So, the correct option is $C$

Question 7

Absolute zero can be defined as the temperature at which:

Accepted Answer

A gas ceases to exist at absolute zero. It is the lowest temperature which can be attained, where volume becomes zero.

Question 8

A thermally isolated gaseous system can exchange energy with the surroundings. The mode of energy may be :

Accepted Answer

Solution:- (B) workAs we know that in thermodynamics, a thermally isolated system can exchange no mass or heat energy with its environment. The internal energy of a thermally isolated system may change due to the exchange of work energy.Hence the mode of energy may be work.

Question 9

For the reaction : $2A(g)+3B\longrightarrow 4C(G) _D (l); \Delta H-=-20 kJ/mole$Find the heat evolved when $0.4$ mole of A reacts with an excess of B in a closed rigid container. The temperature is constant at $300 K$. [R=8.3 J/K mole]

Accepted Answer

$2 {A}_{\left( g \right)} + 3 {B}_{\left( g \right)} \longrightarrow 4 {C}_{\left( g \right)} + {D}_{\left( l \right)}$No. of moles of A $= 0.4$No. of moles of C when $2$ moles of A reacts $= 4 \text{ moles}$No. of moles of C when $0.4$ moles of A reacts $= 0.8 \text{ moles}$No. of moles of B $= 3$ (As B is in excess)Total moles of reactant $= 0.4 + 3 = 3.4$Total moles of product $= 0.8$${\Delta{n}}_{g} = {n}_{P} - {n}_{R} = 0.8 - 3.8 = -3$$\Delta{H} = -20 \; {KJ}/{mol}= -20000\; {J}/{mol}$Temperature $\left( T \right) = 300 K$$\Delta{H} = {q}_{V} + {\Delta{n}}_{g}RT$$\Rightarrow {q}_{V} = \Delta{H} - {\Delta{n}}_{g} RT$$\Rightarrow {q}_{V} = -20000 - \left( -3 \times 8.3 \times 300 \right) = -20000 + 7470 = -12530 \; {J}/{mol} = -12.53 \; {KJ}/{mol}$Hence the required answer is $-12.53 \; {KJ}/{mol}$.

Question 10

The measure of degree of hotness or coldness of a body is called:

Accepted Answer

The measure of degree of hotness or coldness of a body is called temperature.

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Heat and Temperature

Temperature as Measure of Hotness and Coldness and It's Units

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Introduction to Heat and Temperarture

Measurement of Temperature

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Temperature As Measure Of Hotness Or Coldness

In terms of Charles' law, explain why - 273 $^{\circ} C$ is the lowest possible temperature.

A circular metal loop is heated at point $O$ as shown in above Figure.
i) In which direction would heat flow in the loop?
ii) In which order the pins at points P, Q and R fixed with the help of wax fall if points O, P, Q and R are equidistant from each other?

$1$ mole of $H_{2} S O_{4}$ is mixed with $2$ moles of NaOH. The heat evolved will be:

The value of absolute zero temperature in Fahrenheit scale is

When two bodies at different temperatures are placed in thermal contact with each other, heat flows from the body at a higher temperature until they both acquire the same temperature. Assuming that there is no loss of heat to the surroundings, then:

Figure shows two flasks connected to each other. The volume of the flask 1 is twice that of flask 2. The system is filled with an ideal gas at temperature 100 K and 200 K respectively in the flasks. If the mass of the gas in 1 m, then what is the mass of the gas in flask 2 in equilibrium?

Absolute zero can be defined as the temperature at which:

A thermally isolated gaseous system can exchange energy with the surroundings. The mode of energy may be :

For the reaction : $2 A (g) + 3 B ⟶ 4 C (G)_{D} (l); Δ H - = - 20 k J / m o l e$
Find the heat evolved when $0.4$ mole of A reacts with an excess of B in a closed rigid container. The temperature is constant at $300 K$ . [R=8.3 J/K mole]

The measure of degree of hotness or coldness of a body is called:

Revise with Concepts

Heat and Temperature

Temperature as Measure of Hotness and Coldness and It's Units

Learn with Videos

Quick Summary With Stories

Introduction to Heat and Temperarture

Measurement of Temperature

Numericals Problem on Measuring Temperature

Temperature As Measure Of Hotness Or Coldness

In terms of Charles' law, explain why - 273 ∘C is the lowest possible temperature.

A circular metal loop is heated at point O as shown in above Figure. i) In which direction would heat flow in the loop? ii) In which order the pins at points P, Q and R fixed with the help of wax fall if points O, P, Q and R are equidistant from each other?

1 mole of H2​SO4​ is mixed with 2 moles of NaOH. The heat evolved will be:

The value of absolute zero temperature in Fahrenheit scale is

When two bodies at different temperatures are placed in thermal contact with each other, heat flows from the body at a higher temperature until they both acquire the same temperature. Assuming that there is no loss of heat to the surroundings, then:

Figure shows two flasks connected to each other. The volume of the flask 1 is twice that of flask 2. The system is filled with an ideal gas at temperature 100 K and 200 K respectively in the flasks. If the mass of the gas in 1 m, then what is the mass of the gas in flask 2 in equilibrium?

Absolute zero can be defined as the temperature at which:

A thermally isolated gaseous system can exchange energy with the surroundings. The mode of energy may be :

For the reaction : 2A(g)+3B⟶4C(G)D​(l);ΔH−=−20kJ/mole Find the heat evolved when 0.4 mole of A reacts with an excess of B in a closed rigid container. The temperature is constant at 300K. [R=8.3 J/K mole]

The measure of degree of hotness or coldness of a body is called:

In terms of Charles' law, explain why - 273 $^{\circ} C$ is the lowest possible temperature.

A circular metal loop is heated at point $O$ as shown in above Figure.
i) In which direction would heat flow in the loop?
ii) In which order the pins at points P, Q and R fixed with the help of wax fall if points O, P, Q and R are equidistant from each other?

$1$ mole of $H_{2} S O_{4}$ is mixed with $2$ moles of NaOH. The heat evolved will be:

For the reaction : $2 A (g) + 3 B ⟶ 4 C (G)_{D} (l); Δ H - = - 20 k J / m o l e$
Find the heat evolved when $0.4$ mole of A reacts with an excess of B in a closed rigid container. The temperature is constant at $300 K$ . [R=8.3 J/K mole]