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Ch.4 - Chemical Reactions and Chemical Quantities
Chapter 4, Problem 56

Write the balanced chemical equation for the reaction of solid potassium with liquid water.

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Identify the reactants and products in the reaction: Potassium (K) reacts with water (H2O) to form potassium hydroxide (KOH) and hydrogen gas (H2).
Write the unbalanced chemical equation: K(s) + H2O(l) -> KOH(aq) + H2(g).
Balance the equation by adjusting coefficients to ensure the same number of each type of atom on both sides of the equation.
Start by balancing the potassium atoms: Place a coefficient of 2 in front of KOH to balance the potassium atoms.
Balance the hydrogen and oxygen atoms: Adjust the coefficients of H2O and H2 to ensure the number of hydrogen and oxygen atoms are equal on both sides.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Balancing Chemical Equations

Balancing chemical equations involves ensuring that the number of atoms for each element is the same on both sides of the equation. This is based on the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. To balance an equation, coefficients are adjusted in front of the chemical formulas.
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Reactivity of Alkali Metals

Alkali metals, such as potassium, are highly reactive, especially with water. When they react with water, they typically produce a hydroxide and hydrogen gas. This reaction is exothermic, meaning it releases heat, and can be vigorous, sometimes resulting in flames or explosions due to the hydrogen gas produced.
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Products of the Reaction

In the reaction between potassium and water, the products formed are potassium hydroxide (KOH) and hydrogen gas (H2). Potassium hydroxide is a strong base, and the release of hydrogen gas can lead to further reactions, especially if ignited. Understanding the products helps in predicting the behavior of the reactants during the reaction.
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