Chemical Thermodynamics MCQs for NEET — Chemistry Questions with Answers

Due to fall in temperature.

$-\frac{dQ}{dW}=\frac{dQ}{dQ-dE}$; $dE=dW+dQ$; –dW = dQ – dE

$=\frac{n{c}_{p}dT}{n{c}_{p}dT-n{c}_{v}dT}=\frac{c_p}{(c_p-c_v)}$

$=\frac{7R}{2R}$ {for diatomic of gas $c_p=\frac{7R}{2}$}

Backmann thermometer is used to measure low temperature.

The Beckmann differential thermometer is used for measuring small differences in temperature, having readability of around 0.001°C. This makes it useful for the determination of melting points, boiling points and calorimetry. Today it is superseded by sensitive digital thermometers using thermocouples, thermistors.

$Q=\frac{18.94\times 0.632\times 0.998\times 122}{1.89}$ =  $771.1Kcal$ 

Thermodynamics is a reversible process in which surroundings are always equilibrium with system.

Heat energy is also involved when one allotropic form of an element is converted in to another. graphite is the stabler allotrope because the heat of transformation of $C_{\left(diamond\right)}\to C_{\left(graphite\right)}$.

(i) $C_{\left(dia\right)}+O_{2\left(g\right)}=C{O}_{2\left(g\right)}\Delta H=-94.5kcal$

(ii) $C_{\left(graphite\right)}+O_{2\left(g\right)}=C{O}_{2\left(g\right)}\Delta H=-94.0kcal$

$\Delta H_{transformation}=-94.5-(-94.0)$

= –0.5 k cal.

All are the correct statements.

Density is mass per unit volume and specific volume is volume per unit mass.

The heat of formation of HCl is to be calculated on per mole of HCl produced

$\therefore$ heat of formation of HCl = $-\frac{44}{2}$ = -22 kcal.

The statement is definition of Hess's law