Iron And Chlorine Reactions: A Chemistry Guide

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Hey everyone! Chemistry can seem tricky, but let's break down some problems together. We'll tackle questions about iron reacting with chlorine and nitrogen reacting with hydrogen. Let's make this fun and easy to understand. We are going to dive into the world of stoichiometry, so buckle up!

Question 22: Iron and Chlorine Reaction

Let's get started, guys! This question is all about figuring out how much chlorine (in kilograms) reacts with a specific amount of iron atoms. The question goes like this: "With what mass of chlorine (in kg) does 3.01 × 10²⁵ iron atoms react?"

To solve this, we need a few key pieces of information and a clear plan. We will start with the number of iron atoms, use Avogadro's number to convert this to moles, and then use the balanced chemical equation to find the moles of chlorine that react. From there, we'll convert moles of chlorine to grams and then to kilograms.

Here’s how we can work through it step by step:

  1. Convert Iron Atoms to Moles: We know that 1 mole of any substance contains Avogadro's number (6.022 × 10²³) of particles (atoms, molecules, etc.). So, to convert iron atoms to moles, we divide the number of iron atoms by Avogadro's number.

Moles of Fe = (3.01 × 10²⁵ atoms) / (6.022 × 10²³ atoms/mol) ≈ 50 moles of Fe.

  1. Determine the Balanced Chemical Equation: The reaction between iron (Fe) and chlorine (Cl₂) produces iron(III) chloride (FeCl₃). The balanced chemical equation is:

2Fe + 3Cl₂ → 2FeCl₃

This equation tells us that 2 moles of iron react with 3 moles of chlorine.

  1. Calculate Moles of Chlorine: Using the stoichiometry of the balanced equation, we can determine the moles of chlorine that react with 50 moles of iron. From the balanced equation, the mole ratio of Fe to Cl₂ is 2:3. Therefore:

Moles of Cl₂ = (50 moles Fe) × (3 moles Cl₂ / 2 moles Fe) = 75 moles of Cl₂.

  1. Convert Moles of Chlorine to Grams: To convert moles of chlorine to grams, we use the molar mass of Cl₂. The molar mass of Cl₂ is 70.90 g/mol (2 × 35.45 g/mol, since each chlorine molecule contains two chlorine atoms).

Grams of Cl₂ = (75 moles) × (70.90 g/mol) = 5317.5 g of Cl₂.

  1. Convert Grams of Chlorine to Kilograms: Finally, convert grams to kilograms.

Kilograms of Cl₂ = 5317.5 g / 1000 g/kg = 5.3175 kg.

Therefore, approximately 5.32 kg of chlorine reacts with 3.01 × 10²⁵ iron atoms. Thus, the correct answer is A) 5,325.

This is a great example of how we use stoichiometry to connect the microscopic world of atoms and molecules to the macroscopic world of grams and kilograms. Keep practicing, and you'll get the hang of it!

Question 23: Nitrogen and Hydrogen Reaction

Alright, let’s move on to the next problem. It’s all about how hydrogen (H₂) reacts with nitrogen (N₂). The question is: “6 m³ of H₂ reacts with how many moles of N₂?”

To solve this, we'll need to remember a few things about gases and chemical reactions. We'll use the ideal gas law to convert the volume of hydrogen to moles and then use the balanced chemical equation to find the moles of nitrogen. Then we'll convert moles of nitrogen to grams.

Let’s break it down step by step:

  1. Ideal Gas Law: We know that the ideal gas law states that PV = nRT, where:

    • P = pressure
    • V = volume
    • n = number of moles
    • R = ideal gas constant
    • T = temperature

    We also know that at standard temperature and pressure (STP), 1 mole of any ideal gas occupies 22.4 L. Let's assume STP. So, convert the volume of hydrogen to liters and then to moles. This assumption is crucial, so always check if the problem provides conditions or asks for STP conditions. If not, you might need to use the ideal gas law with specific temperature and pressure conditions.

    First, convert m³ to Liters: 6 m³ = 6000 L.

    Then we can find the number of moles of H₂: n = V / 22.4 L/mol = 6000L / 22.4 L/mol ≈ 267.86 moles of H₂.

  2. Balanced Chemical Equation: The reaction between nitrogen and hydrogen to produce ammonia (NH₃) is:

    N₂ + 3H₂ → 2NH₃

    This equation tells us that 1 mole of nitrogen reacts with 3 moles of hydrogen.

  3. Calculate Moles of Nitrogen: Using the mole ratio from the balanced equation, we can determine the moles of nitrogen that react with 267.86 moles of hydrogen.

    Moles of N₂ = (267.86 moles H₂) × (1 mole N₂ / 3 moles H₂) ≈ 89.29 moles of N₂.

So, approximately 89.3 moles of N₂ react with 6 m³ of H₂. Thus, the correct answer is C) 89,3. Good job!

This problem highlights the importance of understanding the ideal gas law and how it relates to stoichiometry. Remember that the balanced chemical equation is the key to relating the amounts of reactants and products.

Question 24: Single-Valence Metal Reaction

Now, let's look at the third question. It deals with a single-valence metal reacting with water. Here’s the question: “2.1 g of a single-valence metal displaces 0.6 L (at standard conditions) of hydrogen from water. What metal is it?”

This is a classic problem involving stoichiometry and the concept of molar mass. We'll start by figuring out the moles of hydrogen gas produced, then use the balanced equation to find the moles of the metal. From there, we'll calculate the molar mass of the metal and identify it based on the periodic table.

Let’s dive into the solution:

  1. Calculate Moles of Hydrogen Gas: At standard conditions (STP), 1 mole of any gas occupies 22.4 L. Given that 0.6 L of hydrogen is produced, we calculate the moles of H₂:

    Moles of H₂ = 0.6 L / 22.4 L/mol ≈ 0.0268 moles of H₂.

  2. Write the Balanced Chemical Equation: Since the metal is single-valent, it means it forms an ion with a +1 charge. The general reaction of a single-valent metal (M) with water is:

    2M + 2H₂O → 2MOH + H₂

    From this equation, we see that 2 moles of the metal produce 1 mole of hydrogen gas. Thus, the mole ratio of metal to hydrogen is 2:1.

  3. Calculate Moles of the Metal: Using the mole ratio from the balanced equation, we determine the moles of metal that reacted:

    Moles of metal = 0.0268 moles of H₂ × (2 moles M / 1 mole H₂) ≈ 0.0536 moles of M.

  4. Calculate the Molar Mass of the Metal: We know the mass of the metal (2.1 g) and the number of moles (0.0536 moles). We can calculate the molar mass:

    Molar mass of M = Mass / Moles = 2.1 g / 0.0536 moles ≈ 39.2 g/mol.

  5. Identify the Metal: Looking at the periodic table, the element with a molar mass close to 39.2 g/mol is potassium (K), which has a molar mass of approximately 39.1 g/mol.

Therefore, the single-valence metal is potassium. Way to go!

This problem nicely combines reaction stoichiometry with the identification of an unknown element. Knowing how to relate the volume of a gas to moles and using the balanced chemical equation are key skills here.

I hope this breakdown was helpful! Feel free to ask more questions. Understanding these concepts will make your journey into chemistry a whole lot easier, guys.