Textbook Question
Little is known about the chemistry of astatine (At) from direct observation, but reasonable predictions can be made.
(a) Is astatine likely to be a gas, a liquid, or a solid?
Ch.22 - The Main Group Elements
Chapter 22, Problem 147
The first preparation of chlorine was similar to the synthesis of elemental bromine (Problem 22.146). A later method entailed the reaction of hydrogen chloride and oxygen at 400 °C. Write a balanced equation for the reaction. (Water is also formed.)
Verified step by step guidance1
Step 1: Identify the reactants and products in the reaction. The reactants are hydrogen chloride (HCl) and oxygen (O2), and the products are chlorine (Cl2) and water (H2O).
Step 2: Write the unbalanced chemical equation using the chemical formulas of the reactants and products: HCl + O2 → Cl2 + H2O.
Step 3: Balance the chlorine atoms. There are two chlorine atoms in Cl2, so you need two HCl molecules to provide two chlorine atoms: 2 HCl + O2 → Cl2 + H2O.
Step 4: Balance the hydrogen atoms. There are two hydrogen atoms in 2 HCl, so you need one H2O molecule to balance the hydrogen: 2 HCl + O2 → Cl2 + H2O.
Step 5: Balance the oxygen atoms. There are two oxygen atoms in O2 and one oxygen atom in H2O, so you need to adjust the coefficients to balance the oxygen atoms: 4 HCl + O2 → 2 Cl2 + 2 H2O.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Balancing Chemical Equations
Balancing chemical equations is essential to ensure that the number of atoms of each element is conserved in a reaction. This involves adjusting the coefficients of the reactants and products so that the total mass remains constant, adhering to the law of conservation of mass. For example, in the reaction of hydrogen chloride and oxygen, one must determine the correct stoichiometric coefficients to balance the equation accurately.
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Chemical Reaction Types
Understanding the types of chemical reactions is crucial for predicting the products and writing balanced equations. The reaction between hydrogen chloride and oxygen is an example of a redox reaction, where oxidation and reduction occur simultaneously. Recognizing the reactants' roles helps in identifying the products, which in this case include chlorine and water.
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Stoichiometry
Stoichiometry involves the calculation of reactants and products in chemical reactions based on their molar ratios. It allows chemists to predict how much of each substance is needed or produced in a reaction. In the context of the given question, stoichiometry will help determine the correct coefficients for hydrogen chloride, oxygen, chlorine, and water in the balanced equation.
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