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8. why do real gases deviate from the ideal gas laws at low temperatures?
o the volume occupied by molecules becomes a significant part of the total volume.
o masses of individual particles increase as kinetic energy decreases.
o attractions between molecules cause a reduction in volume.

Attractions between molecules cause a reduction in volume

Explanation:

This is a very important concept of the ideal gas law application. The ideal gas law applies when several conditions are met:

Therefore, the ideal gas law applies best in scenarios where we have a high temperature and a low pressure (or large volume). The larger the volume gets, the more negligible is the size of a molecule compared to the size of a container.

Speaking of temperature, the greater the temperature, the higher the kinetic energy of the gas molecules, so that the average distances between them increase and the attraction forces are minimized.

However, having a low temperature would cause the molecules of a gas move slower and attraction forces would be more significant due to lower average distances between the molecules.

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol