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Which of the following statements about chemical equations is (are) true? a. When balancing a chemical equation, you can never change the coefficient in front of any chemical formula. b. The coefficients in a balanced chemical equation refer to the number of grams of reactants and products. c. In a chemical equation, the reactants are on the right, and the products are on the left. d. When balancing a chemical equation, you can never change the subscripts of any chemical formula. e. In chemical reactions, matter is neither created nor destroyed, so a chemical equation must have the same number of atoms on both sides of the equation.

Short Answer

Expert verified
The correct statements about chemical equations are: - Statement d: When balancing a chemical equation, you can never change the subscripts of any chemical formula. - Statement e: In chemical reactions, matter is neither created nor destroyed, so a chemical equation must have the same number of atoms on both sides of the equation.

Step by step solution

01

Statement a:

When balancing a chemical equation, you can never change the coefficient in front of any chemical formula. This statement is false. To balance a chemical equation, you need to adjust the coefficients in front of the chemical formulas to ensure that the number of atoms of each element is equal on both the reactant and the product side.
02

Statement b:

The coefficients in a balanced chemical equation refer to the number of grams of reactants and products. This statement is also false. The coefficients refer to the relative number of moles (not grams) of the reactants and products in a balanced chemical equation.
03

Statement c:

In a chemical equation, the reactants are on the right, and the products are on the left. This statement is incorrect. In a chemical equation, the reactants are traditionally written on the left side, and the products are written on the right side. The arrow (→) in the equation separates the reactants from the products and symbolizes the direction of the reaction.
04

Statement d:

When balancing a chemical equation, you can never change the subscripts of any chemical formula. This statement is true. In order to balance a chemical equation, you should only adjust the coefficients in front of the chemical formulas. Changing the subscripts would alter the chemical identity of the substances involved in the reaction, which is not allowed.
05

Statement e:

In chemical reactions, matter is neither created nor destroyed, so a chemical equation must have the same number of atoms on both sides of the equation. This statement is true. This principle, known as the Law of Conservation of Mass, is a fundamental concept in chemistry. It means that the total mass of reactants in a chemical reaction must equal the total mass of the products formed. Consequently, a balanced chemical equation must have an equal number of atoms for each element on both sides of the equation. To sum it up, the true statements about chemical equations are: - Statement d: When balancing a chemical equation, you can never change the subscripts of any chemical formula. - Statement e: In chemical reactions, matter is neither created nor destroyed, so a chemical equation must have the same number of atoms on both sides of the equation.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Law of Conservation of Mass
The Law of Conservation of Mass is a cornerstone in the world of chemistry. It dictates that matter is neither created nor destroyed during a chemical reaction. This principle has profound implications when balancing chemical equations.

When a chemical reaction takes place, the total mass of the substances before the reaction must equal the total mass of the substances after the reaction. This means you'll end up with the same quantity of each type of atom on both sides of the equation.

Here's why this is vital: chemistry seeks to describe and predict how substances interact. Ensuring mass conservation helps preserve accuracy and reliability in these predictions.
  • Your reactants are the substances you start with in a reaction.
  • The products are what you achieve. They appear on the right side of the equation.
  • The arrow indicates the direction of the reaction from reactants to products.
Only by balancing equations can chemists remain true to the law and accurately represent what happens at the atomic level.
Coefficients in Chemical Equations
In a balanced chemical equation, coefficients play a crucial role. They are the numbers placed before molecules and compounds to indicate how many units of each are involved. Adjusting these coefficients ensures each element has an equal number of atoms on both sides of the equation.

Coefficients tell us the relative amount of substances involved in the reaction. They reflect the stoichiometry of the reaction, which is the quantitative relationship between reactants and products.

It’s crucial not to confuse coefficients with subscripts. Subscripts form part of the chemical formula, denoting the number of atoms in a molecule and should never be changed when balancing equations.

For example, in the water formation reaction:
H_2 + O_2 → H_2O,
you might need coefficients like, 2H_2 + O_2 → 2H_2O, to balance the equation, reflecting the stoichiometric balance needed to conserve mass.
Chemical Reaction Fundamentals
Understanding the basics of a chemical reaction is essential. Reactions depict how substances (reactants) change into other substances (products). They can release or absorb energy and involve breaking and forming bonds.

Here's how a chemical equation is arranged:
  • Reactants are on the left side.
  • Products are on the right side.
  • An arrow (→) separates the two sides, showing the flow of the reaction.
This format lets chemists communicate complex reaction details with simplicity.

Chemical reactions can vary. They might involve simple or complex transformations. But the fundamentals like maintaining equal mass and properly using coefficients remain constant.

By understanding these fundamentals, you'll grasp how chemicals interact and change, forming the amazing world of chemistry.

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Most popular questions from this chapter

Many over-the-counter antacid tablets are now formulated using calcium carbonate as the active ingredient, which enables such tablets to also be used as dietary calcium supplements. As an antacid for gastric hyperacidity, calcium carbonate reacts by combining with hydrochloric acid found in the stomach, producing a solution of calcium chloride, converting the stomach acid to water, and releasing carbon dioxide gas (which the person suffering from stomach problems may feel as a "burp"). Write the unbalanced chemical equation for this process.

When elemental boron, \(\mathrm{B}\), is burned in oxygen gas, the product is diboron trioxide. If the diboron trioxide is then reacted with a measured quantity of water, it reacts with the water to form what is commonly known as boric acid, \(\mathrm{B}(\mathrm{OH})_{3} .\) Write a balanced chemical equation for each of these processes.

A common experiment to determine the relative reactivity of metallic elements is to place a pure sample of one metal into an aqueous solution of a compound of another metallic element. If the pure metal you are adding is more reactive than the metallic element in the compound, then the pure metal will replace the metallic element in the compound. For example, if you place a piece of pure zinc metal into a solution of copper(II) sulfate, the zinc will slowly dissolve to produce zinc sulfate solution, and the copper(II) ion of the copper(II) sulfate will be converted to metallic copper. Write the unbalanced equation for this process.

If you've ever left bread in a toaster too long, you know that the bread eventually burns and turns black. What evidence is there that this represents a chemical process?

Acetylene gas, \(\mathrm{C}_{2} \mathrm{H}_{2},\) is used in welding because it generates an extremely hot flame when it is combusted with oxygen. The heat generated is sufficient to melt the metals being welded together. Carbon dioxide gas and water vapor are the chemical products of this reaction. Write the unbalanced chemical equation for the reaction of acetylene with oxygen.

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