Learn
Games

1.11 - EXERCISES

Interactive Audio Lesson

Listen to a student-teacher conversation explaining the topic in a relatable way.

Calculating Molar Mass

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

Teacher
Teacher

Today, we'll begin by calculating the molar mass of different compounds. Can anyone tell me what molar mass is?

Student 1
Student 1

Isn't it the mass of one mole of a substance?

Teacher
Teacher

Exactly! The molar mass tells us how much one mole weighs in grams. Let's take water, H2O, as our first example. Can anyone help me calculate its molar mass?

Student 2
Student 2

It has two hydrogen atoms and one oxygen atom. So, it's 2 times 1.008 for H and 16.00 for O!

Teacher
Teacher

Right! So that comes to 18.016 g/mol. Remember this calculation because it will help you with future exercises!

Student 3
Student 3

Could we do another example, like CO2?

Teacher
Teacher

Absolutely! For CO2, we have one carbon atom and two oxygen atoms. Who can calculate that?

Student 4
Student 4

That would be 12.01 for C and 2 times 16.00 for O, so it’s 44.01 g/mol!

Teacher
Teacher

Great job! Remember to always add the atomic masses based on the periodic table.

Concentration Calculations

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

Teacher
Teacher

Next, let's talk about concentration. How many of you know how to calculate the molarity of a solution?

Student 1
Student 1

It’s the number of moles of solute per liter of solution, right?

Teacher
Teacher

Correct! For example, if we dissolve 20 g of sugar in enough water to make 2 liters of solution, how would we find the molarity?

Student 2
Student 2

We’d need to convert grams to moles first.

Teacher
Teacher

Exactly! The molar mass of sugar is 342.30 g/mol. So how many moles do we have?

Student 3
Student 3

That’s about 0.058 moles.

Teacher
Teacher

Now can anyone figure out the molarity?

Student 4
Student 4

That would be 0.058 moles divided by 2 liters, which equals 0.029 M!

Teacher
Teacher

Great work! Molarity helps us understand the concentration of solutions which is crucial in reactions.

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section presents various exercises related to molar mass calculations, concentrations, and chemical reactions.

Standard

The exercises focus on key topics such as calculating molar masses, determining empirical formulas, and applying concentration formulas. Each problem aims to reinforce understanding of chemical principles and their applications in real-world scenarios.

Detailed

In-depth Summary

The exercises in this section cover a variety of fundamental concepts in chemistry, emphasizing calculations crucial for understanding chemical reactions and solutions.

  1. Molar Mass Calculations: Students practice calculating molar masses for compounds like water (H2O), carbon dioxide (CO2), and methane (CH4).
  2. Mass Percentages: An exercise involves determining the mass percent of different elements in sodium sulfate (Na2SO4).
  3. Empirical and Molecular Formulas: Students learn to derive empirical formulas from given composition percentages and convert them into molecular formulas using mass percentages of elements like iron and oxygen.
  4. Stoichiometry: A series of problems guides students through calculating the amount of products formed in combustion reactions, such as burning carbon in air.
  5. Concentration Calculations: Exercises include determining concentrations of various solutions, such as sodium acetate and nitric acid, reinforcing the relationship between concentration, volume, and mass.
  6. Gas Laws and Reactions: Students analyze chemical reactions involving gases, understand limiting reagents, and apply Avogadro's principles.

By engaging with these exercises, students cultivate a robust foundational knowledge required for advanced studies in chemical sciences.

Youtube Videos

Some Basic Concepts of Chemistry class 11 chemistry chapter 1 exercise solutions
Some Basic Concepts of Chemistry class 11 chemistry chapter 1 exercise solutions
Class 11th Chemistry Chapter 1 | Exercise Questions (1 to 36) | Some Basic Concepts of Chemistry
Class 11th Chemistry Chapter 1 | Exercise Questions (1 to 36) | Some Basic Concepts of Chemistry
11th CHEMISTRY | 1.SOME BASIC CONCEPTS OF CHEMISTRY | Exercise Numericals | PRADEEP GIRI SIR
11th CHEMISTRY | 1.SOME BASIC CONCEPTS OF CHEMISTRY | Exercise Numericals | PRADEEP GIRI SIR
Some Basic Concepts of Chemistry|NCERT EXERCISE #somebasicconceptsofchemistry #ncertsolutions
Some Basic Concepts of Chemistry|NCERT EXERCISE #somebasicconceptsofchemistry #ncertsolutions

Audio Book

Dive deep into the subject with an immersive audiobook experience.

Concentration Calculation

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

1.11 What is the concentration of sugar (C12H22O11) in mol L–1 if its 20 g are dissolved in enough water to make a final volume up to 2L?

Detailed Explanation

To find the concentration of sugar (C12H22O11) in mol/L, we need to follow a few steps:
1. Calculate the Molar Mass: First, we need to determine the molar mass of sugar (C12H22O11). The atomic weights from the periodic table are approximately:
- Carbon (C): 12.01 g/mol
- Hydrogen (H): 1.008 g/mol
- Oxygen (O): 16.00 g/mol
Thus, the molar mass of C12H22O11 can be calculated as:
- Molar mass = (12 * 12.01) + (22 * 1.008) + (11 * 16.00) = 342.30 g/mol
2. Convert Grams to Moles: Next, convert the mass in grams (20 g) to moles using the following formula:
- Moles = mass (g) / molar mass (g/mol)
- Moles = 20 g / 342.30 g/mol ≈ 0.0584 mol
3. Calculate the Concentration: Finally, we can calculate the concentration (C) using the formula:
- Concentration (C) = moles of solute / volume of solution (L)
- Concentration (C) = 0.0584 mol / 2 L = 0.0292 mol/L.
Thus, the concentration of sugar in the solution is 0.0292 mol/L.

Examples & Analogies

Imagine you are baking cookies. If you add 20 grams of sugar to your mixing bowl and then mix it with enough water to fill a large jug to 2 liters, you can imagine the sugar dissolving and becoming part of that liquid. To understand how sweet your cookies will be, you can think of the concentration as the sweetness level. The more sugar you add for the same amount of water, the sweeter the cookies will taste.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Molar Mass: The mass of one mole of a substance, derived from the atomic masses of its elements.

  • Molarity: A unit of concentration defined as moles of solute per liter of solution.

  • Stoichiometry: The calculation that enables prediction of quantities of reactants and products in chemical reactions.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • For H2O, the molar mass is 18.01 g/mol (2 H x 1.008 + 1 O x 16.00).

  • To find the concentration of a 0.375 M sodium acetate solution, recall that molarity equals moles of solute divided by liters of solution.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • To find the mass in grams, add molar bits, H and O in water fit!

📖 Fascinating Stories

  • Imagine a chemist named Molly who loved mixing solutions. She learned that finding molarity was about her favorite ingredient's mass in a big pot of water!

🧠 Other Memory Gems

  • Mice Munch Sweet Snacks — M= molarity, M= moles, V= volume.

🎯 Super Acronyms

M for Moles, V for Volume, C for Concentration — Remember MVC for molarity!

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Molar Mass

    Definition:

    The mass of one mole of a substance, typically expressed in grams per mole (g/mol).

  • Term: Concentration

    Definition:

    The amount of solute per unit volume of solution, usually expressed in moles per liter (M).

  • Term: Empirical Formula

    Definition:

    The simplest whole-number ratio of the elements in a compound.

  • Term: Molecular Formula

    Definition:

    The actual number of atoms of each element in a molecule of a compound.

  • Term: Stoichiometry

    Definition:

    The calculation of reactants and products in chemical reactions.