Question

Write a balanced equation for each of the following single-replacement reactions: (a) A gray chunk of cesium is added to water. (b) A piece of radioactive radium is added to water.

Short answer

(a) \( 2Cs + 2H_2O \rightarrow 2CsOH + H_2 \); (b) \( Ra + 2H_2O \rightarrow Ra(OH)_2 + H_2 \).

Step-by-step solution

Understanding the Reaction Type

In single-replacement reactions, one element replaces another in a compound. The general form is \( A + BC \rightarrow AC + B \), where \( A \) is an element and \( BC \) is a compound.

Writing the Unbalanced Equation for Cesium and Water

Cesium \((Cs)\) reacts with water \((H_2O)\). The products of this reaction are hydrogen gas \((H_2)\) and cesium hydroxide \((CsOH)\). The equation is initially written as:\[ Cs + H_2O \rightarrow CsOH + H_2 \]

Balancing the Equation for Cesium and Water

To balance the equation, ensure the number of each type of atom is equal on both sides. Adjust coefficients as necessary:\[ 2Cs + 2H_2O \rightarrow 2CsOH + H_2 \]

Writing the Unbalanced Equation for Radium and Water

Radium \((Ra)\) reacts with water \((H_2O)\). The products of this reaction are hydrogen gas \((H_2)\) and radium hydroxide \((Ra(OH)_2)\). The equation is initially:\[ Ra + H_2O \rightarrow Ra(OH)_2 + H_2 \]

Balancing the Equation for Radium and Water

Balance the chemical equation by ensuring equal atom counts on both sides. Adjust the coefficients:\[ Ra + 2H_2O \rightarrow Ra(OH)_2 + H_2 \]

Final Balanced Equations

The balanced equations for the reactions are:- For cesium and water: \( 2Cs + 2H_2O \rightarrow 2CsOH + H_2 \).- For radium and water: \( Ra + 2H_2O \rightarrow Ra(OH)_2 + H_2 \).

Key concepts

Balancing Equations

Balancing chemical equations is an essential skill in chemistry. It ensures that we abide by the Law of Conservation of Mass, which states that mass cannot be created or destroyed in a chemical reaction. To balance an equation, the number of atoms of each element must be the same on both sides of the equation. This is done by adjusting coefficients, which are numbers placed before chemical formulas to indicate the number of molecules or moles. Consider the reaction of cesium and water as an example:

• Unbalanced: \( Cs + H_2O \rightarrow CsOH + H_2 \)
• Balanced: \( 2Cs + 2H_2O \rightarrow 2CsOH + H_2 \)

Here, by multiplying the number of water molecules and cesium by two, we achieve balance. Balancing equations may seem tricky at first, but with practice, it becomes a straightforward task! Always remember to check your work by counting the atoms on both sides of the equation.

Single-Replacement Reactions

In a single-replacement reaction, one element replaces another in a compound. These reactions follow the general form: \( A + BC \rightarrow AC + B \). Here, \( A \) is usually a more reactive metal that replaces a similar element in the compound \( BC \). This means the reaction depends on the reactivity of the elements involved.Let's look at the reaction of cesium with water:

• Chemical equation: \( Cs + H_2O \rightarrow CsOH + H_2 \)

Cesium, a more reactive element, replaces hydrogen in water, forming cesium hydroxide and releasing hydrogen gas. Another example is radium reacting with water:

• Chemical equation: \( Ra + H_2O \rightarrow Ra(OH)_2 + H_2 \)

In this case, radium replaces hydrogen, leading to the formation of radium hydroxide. Not all elements can replace each other. The ability to replace depends on the activity series, a list that ranks elements by their reactivity.

Chemical Reactions

Chemical reactions are processes where substances, known as reactants, are transformed into different substances called products. These reactions are at the heart of chemistry, illustrating how elements interact to form compounds with different properties. Reactions can be classified into several types, such as:

• Single-replacement reactions
• Double-replacement reactions
• Synthesis reactions
• Decomposition reactions
• Combustion reactions

In our case, single-replacement reactions are studied to understand how one element can replace another in a compound, leading to new product formation. For example, when cesium reacts with water, cesium hydroxide and hydrogen gas are formed. Understanding these reactions helps us predict the products formed and their applications, such as hydrogen gas being a potential source of clean energy. Chemical reactions are fundamental to science, influencing everything from industrial processes to biological mechanisms. They show the dynamic nature of elements, continually interacting and transforming in our world.