Question

Sodium metal reacts with liquid water to form a solution of sodium hydroxide and hydrogen gas. Potassium reacts in a similar manner. Write a balanced equation to represent the reaction of potassium with water.

Short answer

The balanced equation representing the reaction of potassium with water is: \(2K + 2H_2O \rightarrow 2KOH + H_2\)

Step-by-step solution

Comprehend the reaction

Potassium (K) reacts with water (H2O) to produce potassium hydroxide (KOH) and hydrogen gas (H2). This can be initially written as: \(K + H_2O \rightarrow KOH + H_2\).

Balancing Hydrogen atoms

On the left side, there are 2 hydrogen atoms in water molecule, on the right side there are two hydrogen atoms in the potassium hydroxide molecule and another two in the hydrogen gas molecule making a total of 4 hydrogen atoms. To balance this, add a coefficient of 2 in front of the potassium hydroxide (KOH) on the right side. The equation then becomes: \(K + H_2O \rightarrow 2KOH + H_2\).

Balancing Potassium atoms

After Step 2, potassium atoms are not balanced as there are 2 potassium atoms on the right side (in 2KOH) and only 1 on the left side (in K). Correct this by placing a coefficient of 2 in front of K on the left side of the equation. The equation is now: \(2K + H_2O \rightarrow 2KOH + H_2\).

Balancing Oxygen atoms

Finally, ensure that the oxygen atoms are balanced. As there are 2 oxygen atoms on the right side (in 2KOH) and only 1 on the left side (in H2O), adjust by adding a coefficient of 2 in front of water (H2O) on the left. The final balanced equation is: \(2K + 2H_2O \rightarrow 2KOH + H_2.\)

Key concepts

Balancing Chemical Equations

Balancing chemical equations is a fundamental skill in chemistry, telling you exactly how much of each substance reacts and is produced. This is key for understanding reactions.
Start with the unbalanced equation, which shows reactants and products.

• To balance, adjust coefficients (numbers in front of molecules) ensuring each element has equal counts on both sides.
• First, balance elements appearing in a single molecule on each side.
• The balance of hydrogen, for example, may need adjusting if it appears in multiple compounds.

This ensures conservation of mass, as per the law of conservation of matter. It's like both sides of a scale - you must have the same weight on each side for balance!
Use trial and error, start with tricky molecules, and adjust as needed.

Stoichiometry

Stoichiometry is the math behind chemical equations and reactions.
It's essential for predicting yields, determining amounts of reactants and products, and scaling reactions up or down.

• This involves mole ratios, derived from the coefficients of balanced chemical equations.
• Moles are a counting unit in chemistry, similar to dozens in a bakery — they quantify atoms and molecules.
• By knowing mole ratios, you can convert the amount of one reactant to a product using dimensional analysis.

In the potassium-water example, stoichiometry tells us how much potassium and water make how much potassium hydroxide and hydrogen gas.
It ensures precise handling of materials in labs and industry, making chemistry precise and predictable.

Chemical Equations

Chemical equations represent chemical reactions. They are the written summary of what happens when substances react.

• Equations use symbols (like \( K \) for potassium) to show reactants and products.
• Subscripts indicate atoms in molecules (\( H_2O \) means two hydrogens and one oxygen).
• Reactions are shown with arrows, with reactants on the left and products on the right.

In our exercise, potassium \((K)\) reacts with water \((H_2O)\) to make potassium hydroxide \((KOH)\) and hydrogen gas \((H_2)\).
Chemical equations offer a clear picture of transformations in matter, providing a universal language for chemists worldwide.
They are also like recipes, giving precise instructions for reaction processes.