Skip to content
Login Register

#moles calculation

7 public questions tagged with this topic.

Partial Pressures and Gas Mixtures

A gas occupies 16.8 litres at STP. How many moles are present? (Molar volume at STP = 22.4 litres)

**Dalton's law of partial pressures** total pressure P_total = Σ P_i, P_i = X_i P_total, X_i mole tion, each gas exerts pressure as if alone, ideal gas mixture P_i V = n_i R T, partial pressure proportional to mole tion, e.g., air 79% N₂ 21% O₂ P_N₂=0.79 atm P_O₂=0.21 atm at 1 atm total. Number of moles (μ) = VolumeMolar volume.μ = (16.8)/(22.4) = 0.75 mol. Substituting values gives 0.75 mol, which matches expected kinetic theory result, confirming mean free path λ = 1/(√2 n π d²), ideal gas law P V = n R T and v_rms = √(3 R T/M) relations.

Ref: NCERT > Physics Book > Behaviour of Perfect Gas and Kinetic Theory > Partial Pressures and Gas Mixtures

View Details
RMS Speed and Temperature Dependence

A gas occupies 28.0 litres at STP. How many moles are present? (Molar volume at STP = 22.4 litres)

**Maxwell-Boltzmann distribution** gives distribution of speeds, v_rms = √(3kT/m), most probable v_mp = √(2kT/m), average v_avg = √(8kT/πm), all ∝ √T, ratio v_rms:v_avg:v_mp =1.732:1.596:1.414, temperature raises all speeds proportionally. Number of moles (μ) = VolumeMolar volume.μ = (28.0)/(22.4) = 1.25 mol. Substituting values gives 1.25 mol, which matches expected kinetic theory result, confirming mean free path λ = 1/(√2 n π d²), ideal gas law P V = n R T and v_rms = √(3 R T/M) relations.

Ref: NCERT > Physics Book > Behaviour of Perfect Gas and Kinetic Theory > RMS Speed and Temperature Dependence

View Details
Gas Laws and Volume-Temperature Relations

A gas occupies 56.0 litres at STP. How many moles are present? (Molar volume at STP = 22.4 litres)

**Ideal gas law** P V = n R T governs gas laws, at constant pressure V ∝ T, so temperature increase 300 K→600 K doubles volume 24→48 L. Charles' law quantitative prediction V₂ = V₁×(T₂/T₁), illustrating direct proportionality, absolute temperature must be in kelvin. Number of moles (μ) = VolumeMolar volume.μ = (56.0)/(22.4) = 2.5 mol. Substituting values gives 2.5 mol, which matches expected kinetic theory result, confirming mean free path λ = 1/(√2 n π d²), ideal gas law P V = n R T and v_rms = √(3 R T/M) relations.

Ref: NCERT > Physics Book > Behaviour of Perfect Gas and Kinetic Theory > Gas Laws and Volume-Temperature Relations

View Details
Werner's Theory and Definitions - Ligands Coordination Number

How many moles of AgCl are precipitated when 1 mole of [CoCl(NH₃)5]Cl₂ is treated with excess AgNO₃?

In [CoCl(NH₃)5]Cl₂, the two Cl− ions outside the coordination sphere are ionizable and precipitate as AgCl. The Cl inside is bonded to Co and does not precipitate. Thus, 2 moles of AgCl form.

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Werner's Theory and Definitions - Ligands Coordination Number

View Details
Water and Mole Concept

How many moles of NaCl are present in 500 mL of a 2M solution?

1 is the correct answer as it accurately identifies the biological location, composition, or distribution described in this question. In Water and Mole Concept, the spatial organization and localization of molecules are critical to their function. 1 is specifically associated with the structure or compartment mentioned because of its unique biochemical properties and physiological role. The other options (0.5, 2, and 4) are primarily associated with different cellular compartments, tissues, or structural contexts.

Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 2

View Details