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Some Basic Concepts of Chemistry appeared 30 times across 3 years — 3.5% of Chemistry. This question is from Stoichiometry and Limiting Reagent.

Year 2026 2025 2024 Total
Questions 8 15 7 30

Butane reacts with oxygen to produce carbon dioxide and water following the equation given below: [cite: 461, 463] C₄H10(g) + (13)/(2)O₂(g) arrow 4CO₂(g) + 5H₂O(l) If 174.0 kg of butane is mixed with 320.0 kg of O₂, the volume of water formed in litres is . (Nearest integer) [cite: 465, 466] [Given: (a) Molar mass of C, H, O are 12, 1, 16 g mol⁻¹ respectively, (b) Density of water = 1 g mL⁻¹] [cite: 467, 468]

Numerical Answer Type:
Enter a numerical value Answer: 137.5 to 138.5 +4 marks

Solution & Explanation

Related Formula
Moles (n) = Mass in gramsMolar Mass Volume of water (V) = Mass of waterDensity of water
Core Logic

First, calculate initial molar quantities for both reactants:

  • Molar mass of C₄H₁₀ = 4(12) + 10(1) = 58 g/mol
  • Initial Moles of butane = 174.0 × 10³ g58 g/mol = 3000 mol = 3 × 10³ mol
  • Molar mass of O₂ = 32 g/mol
  • Initial Moles of oxygen = 320.0 × 10³ g32 g/mol = 10000 mol = 10 × 10³ mol
Step 1: Identify Limiting Reagent

Let's test the stoichiometric requirements via calculation ratios:

  • Ratio for C₄H₁₀ = (3000)/(1) = 3000
  • Ratio for O₂ = (10000)/(13/2) = 1538.46
  • Since the ratio for O₂ is lower, oxygen behaves as the limiting reagent and commands the output steps.

Step 2: Compute Water Yield

Using stoichiometric proportions defined by the balanced reaction field:

Moles of H2O = 5 × Moles of O213/2 = 5 × (2)/(13) × 10000 = (100000)/(13) mol

Convert moles to mass (MH2O = 18 g/mol):

Mass of water = (100000)/(13) × 18 = 138461.5 g ≈ 138.46 kg

Since density = 1 g/mL = 1 kg/L, the net volume is exactly:

Vwater = 138.46 Litres ≈ 138 Litres
Pattern Recognition

Limiting reagent shortcut: Always check ratios (moles / stoichiometric coefficient) right away. Do not spend time calculating theoretical products based on butane before establishing whether oxygen runs out first.

Chapter Mix

Class 11 Chemistry: Some Basic Concepts of Chemistry

Reference Study Guides

More Some Basic Concepts of Chemistry Previous-Year Questions — Page 5

Q50 jee_main_2025_24_jan_morning Stoichiometry and Limiting Reagent
Consider the following reaction occurring in the blast furnace. F e _ 3 O _ 4 (s) + 4 C O _ (g) arrow 3 F e _ (l) + 4 C O _ 2 (g) x kg of iron is produced when 2.32× 10³kg Fe₃O₄ and 2.8× 10²kg CO are brought together in the furnace. The value of x is ______ (nearest integer) {Given: Molar mass of Fe₃O₄ = 232 g mol⁻¹ Molar mass of CO = 28 g mol⁻¹ Molar mass of Fe = 56 g mol⁻¹}
Numerical Answer. Answer: 420 to 420

Solution

Related Formula
Moles (n) = Mass in gramsMolar Mass
Core Logic

First, calculate the input moles for each reactant:

  • Moles of Fe₃O₄ = 2.32 × 10³ × 10³ g232 g mol⁻¹ = 10,000 moles
  • Moles of CO = 2.8 × 10² × 10³ g28 g mol⁻¹ = 10,000 moles
  • Next, identify the limiting reagent by comparing the available moles to the stoichiometric coefficients:

  • For Fe₃O₄: (10000)/(1) = 10000
  • For CO: (10000)/(4) = 2500
  • Since 2500 < 10000, carbon monoxide (CO) is the limiting reagent.

    Now, determine the production yield of iron based on the limiting reagent (CO):

Moles of Fe produced = (3)/(4) × n(CO) = (3)/(4) × 10000 = 7500 moles

Convert these moles into kilograms to find the final mass (x):

Mass of Fe = 7500 × 56 g/mol1000 g/kg = 420 kg
Pattern Recognition

Always identify the limiting reagent first by normalizing the mole quantities with their respective stoichiometric coefficients before calculating product yields.

Chapter Mix

Class 11 Chemistry: Some Basic Concepts of Chemistry

Q35 jee_main_2025_28_jan_evening Concentration Terms
Concentrated nitric acid is labelled as 75% by mass. The volume in mL of the solution which contains 30 g of nitric acid is Given: Density of nitric acid solution is 1.25 g/mL
  • A. 45
  • B. 55
  • C. 32
  • D. 40

Solution

Related Formula

Mass percentage definition:

% w/w = Mass of soluteMass of solution × 100

Density conversion equation:

Volume of solution = Mass of solutionDensity of solution
Core Logic

A value of 75% w/w HNO₃ implies that 75 g of pure HNO₃ is present in 100 g of solution.

We need to find the volume that provides exactly 30 g of pure acid solute.

Step 1: Calculate Solution Mass and Volume

Mass of solution needed for 30 g solute:

Mass = (100)/(75) × 30 = 40 g

Converting mass to volume using solution density (1.25 g/mL):

Volume = 40 g1.25 g/mL = 32 mL
Pattern Recognition

Break concentration steps down clearly: Mass of solute arrow Mass of solution arrow Volume of solution. Combining operations: Volume = Mass solute% × 100density = (30)/(75) × (100)/(1.25) = 0.4 × 80 = 32.

Chapter Mix

Class 11 Chemistry: Some Basic Concepts of Chemistry

Q jee_main_2025_29_jan_morning Properties of Matter and Their Measurement
Choose the correct statements. (A) Weight of a substance is the amount of matter present in it. (B) Mass is the force exerted by gravity on an object. (C) Volume is the amount of space occupied by a substance. (D) Temperatures below 0°C are possible in Celsius scale, but in Kelvin scale negative temperature is not possible. (E) Precision refers to the closeness of various measurements for the same quantity.
  • A. (B), (C) and (D) Only
  • B. (A), (B) and (C) Only
  • C. (A), (D) and (E) Only
  • D. (C), (D) and (E) Only

Solution

Related Formula
TK = T°C + 273.15

Absolute zero (0 K) represents the lowest theoretical temperature limit.

Core Logic

Analyzing each statement based on foundational definitions :

  • (A) & (B) Incorrect: Mass is the actual matter present; weight is the gravitational force exerted on that mass. These definitions are reversed in the statements.
  • (C) Correct: Volume correctly defines the space occupied by a substance .
  • (D) Correct: Celsius values can be negative, whereas Kelvin scale strictly defaults to absolute zero (0 K) as minimum .
  • (E) Correct: Precision measures how close experimental trials lie relative to each other .
  • Therefore, statements (C), (D), and (E) are correct.

Pattern Recognition

Absolute temperature scale (Kelvin) can never possess real negative values because 0 K represents complete cessation of molecular motion.

Chapter Mix

Class 11 Chemistry: Some Basic Concepts of Chemistry

Q77 jee_main_2024_01_february_morning Titration
Given below are two statements : Statement (I): Potassium hydrogen phthalate is a primary standard for standardisation of sodium hydroxide solution. Statement (II) : In this titration phenolphthalein can be used as indicator. In the light of the above statements, choose the most appropriate answer from the options given below:
  • A. Both Statement I and Statement II are correct
  • B. Statement I is correct but Statement II is incorrect
  • C. Statement I is incorrect but Statement II is correct.
  • D. Both Statement I and Statement II are incorrect.

Solution

Core Logic

Statement (I): Potassium hydrogen phthalate (KHP) is widely used as a primary standard in analytical chemistry for standardizing strong bases like NaOH. This is because it is highly pure, non-hygroscopic, stable, and has a relatively high molar mass, making its concentration reliable and stable over time.

Statement (II): KHP is a weak acid and NaOH is a strong base. The titration of a weak acid with a strong base yields an equivalence point in the weakly basic range (pH > 7). Phenolphthalein changes colour in the pH range 8.3 to 10.0, making it the perfect indicator for this titration.

Step 1: Evaluate Statements

Statement I is correct. Statement II is correct.

Pattern Recognition

Weak Acid vs Strong Base arrow Equivalence pH > 7 arrow Phenolphthalein is the indicator of choice.

Chapter Mix

Class 11 Chemistry: Equilibrium Class 11 Chemistry: Some Basic Concepts of Chemistry

Q89 jee_main_2024_01_february_morning Stoichiometry
Consider the following reaction: 3PbCl₂ + 2(NH₄)₃PO₄ arrow Pb₃(PO₄)₂ + 6NH₄Cl If 72 ~mmol of PbCl₂ is mixed with 50 ~mmol of (NH₄)₃PO₄, then amount of Pb₃(PO₄)₂ formed is ... mmol. (nearest integer)
Numerical Answer. Answer: 24 to 24

Solution

Related Formula
Moles of Product = Moles of Limiting Reagent × Stoichiometry of ProductStoichiometry of Limiting Reagent
Core Logic

From the balanced chemical equation: 3 moles of PbCl₂ react with 2 moles of (NH₄)₃PO₄.

Let's find the limiting reagent (L.R.) by dividing given millimoles by stoichiometric coefficients: For PbCl₂: (72)/(3) = 24 For (NH₄)₃PO₄: (50)/(2) = 25

Since 24 < 25, PbCl₂ is the limiting reagent and will completely consume.

Step 1: Calculate Product Moles

Moles of Pb₃(PO₄)₂ formed depends entirely on PbCl₂. 3 mmol of PbCl₂ produces 1 mmol of Pb₃(PO₄)₂. Therefore, 72 mmol of PbCl₂ will produce: (1)/(3) × 72 = 24 ~mmol of Pb₃(PO₄)₂.

Pattern Recognition

Always identify the Limiting Reagent by taking the ratio n / coefficient. The smallest ratio dictates the extent of the reaction.

Chapter Mix

Class 11 Chemistry: Some Basic Concepts of Chemistry

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