Air contains mostly nitrogen (78%) and oxygen (21%). it also contains other gases, including carbon dioxide and helium, and various pollutants (both gases and solids). write a brief explanation about why air is a mixture, whether it is homogeneous or heterogeneous, and how it can be separated into its components.

Air is a mixture as it contains more than one type of substance that can be a mixture of gases only or including solid particles.

The mixture is the presence of two or more types of substances physically together. In the mixture, each component exhibits its original properties and can be easily separated.

On the basis of the state of components mixture are two types:

The components of air can be separated by:

Electrostatic precipitation: It is used to remove solid pollutants from air such as dust particles and other particles.

Fractional distillation: it is used for the separation of a mixture into its component parts, it helps in separating various gases from the air.

Learn more about separation of air:

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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