Unit 7 - Chemical Reactions Test

A balanced chemical equation is one that has the same number of atoms of each element on both sides of the equation. This means that the equation obeys the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. By ensuring that the number of atoms of each element is equal on both sides, a balanced equation accurately represents the reactants and products involved in the reaction.

The breaking down of a substance into two or more substances is referred to as decomposition. This process involves the separation of a compound into its individual elements or simpler compounds. It is the opposite of synthesis, which involves the combination of substances to form a more complex compound. Displacement refers to the replacement of one element by another in a compound, and endothermic describes a reaction that absorbs heat from its surroundings.

The term "products" correctly describes the part identified on the right side of the equation. In a chemical equation, the reactants are on the left side and the products are on the right side. The products are the substances that are formed as a result of the chemical reaction.

In a chemical equation, the substances on the left side of the arrow are called reactants. Reactants are the starting materials that undergo a chemical reaction to form new substances, known as products, which are located on the right side of the arrow. Coefficients are used to balance the equation and indicate the relative amounts of each substance involved in the reaction. Catalysts, on the other hand, are substances that increase the rate of a chemical reaction without being consumed in the process.

According to the law of conservation of mass, the total mass of the reactants must be equal to the total mass of the products in a chemical reaction. Since two atoms of hydrogen are used as a reactant, in order to conserve mass, there must also be two atoms of hydrogen as part of the product.

In a chemical equation, the substances to the right of the arrow represent the products. These are the new substances that are formed as a result of the chemical reaction. Therefore, the correct answer is "product".

A catalyst is a substance that speeds up a chemical reaction without undergoing a permanent change itself. It works by providing an alternative pathway with lower activation energy for the reaction to occur. This allows the reaction to proceed at a faster rate, but the catalyst remains unchanged and can be used again in subsequent reactions. In contrast, an inhibitor slows down or prevents a chemical reaction, a coefficient is a number that appears in front of a chemical formula to balance the equation, and a reactant is a substance that participates in a chemical reaction.

A chemical reaction in which two or more substances combine to form another substance is known as a synthesis reaction. In this type of reaction, the reactants come together to create a new product. This process involves the formation of chemical bonds between the reactants, resulting in the creation of a more complex substance. Synthesis reactions are commonly observed in various chemical processes, such as the formation of water from hydrogen and oxygen molecules.

The left side of an equation represents the reactants, which are the substances that undergo a chemical reaction to form new products. In a chemical equation, the reactants are typically written on the left side of the arrow, indicating that they are the starting materials for the reaction. The reactants are the substances that are consumed or used up during the reaction.

When one element replaces another element in a compound, the reaction is a single-displacement reaction. In this type of reaction, a more reactive element displaces a less reactive element in a compound, resulting in the formation of a new compound and a free element. This reaction is also known as a substitution reaction, where one element is substituted for another in a compound.

According to the law of conservation of mass, the total mass of the reactants in a chemical reaction is always equal to the total mass of the products. This means that no mass is gained or lost during a chemical reaction. The atoms in the reactants rearrange to form new products, but the total number of atoms and their mass remains the same. Therefore, the correct answer is that the masses are equal.

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Substances that prevent certain chemical reactions are called inhibitors. Inhibitors work by slowing down or stopping the reaction by interfering with the active sites of enzymes or by blocking the formation of the transition state in a chemical reaction. They are commonly used in industries to control the rate of reactions or to prevent unwanted reactions from occurring.

The big 2 in "2H2O" is a coefficient. In chemical equations, coefficients are used to balance the number of atoms on both sides of the equation. In this case, the coefficient 2 indicates that there are two molecules of water (H2O) involved in the reaction.

If a chemical reaction requires energy in the form of heat to occur, it is considered endothermic. In an endothermic reaction, heat is absorbed from the surroundings, causing a decrease in temperature. This type of reaction is characterized by the breaking of bonds within the reactants, which requires energy input. As a result, the products have more energy than the reactants, and the reaction is not spontaneous.

The small 2 in "2H2O" is a subscript. In chemical equations, subscripts are used to indicate the number of atoms or molecules of each element in a compound. In this case, the subscript 2 indicates that there are two molecules of water (H2O) present.

An exothermic reaction is a chemical reaction that releases energy, primarily in the form of heat. This means that the products of the reaction have less energy than the reactants, resulting in the release of heat. This is opposite to an endothermic reaction, where energy is absorbed from the surroundings. Flammable refers to the ability of a substance to catch fire, while endergonic refers to a reaction that requires energy input. Therefore, the correct answer is exothermic.

The chemical equation NH3 + HCl → NH4Cl represents a synthesis reaction. In a synthesis reaction, two or more reactants combine to form a single product. In this case, ammonia (NH3) and hydrochloric acid (HCl) react to form ammonium chloride (NH4Cl).

In a double-displacement reaction, two compounds react to form two new compounds, one of which is often an insoluble solid called a precipitate. This solid forms when the cations and anions in the reactants switch partners, resulting in the formation of a new compound that is not soluble in the solvent. Therefore, the correct answer is "a precipitate."

The given equation shows a decomposition reaction. In this type of reaction, a compound breaks down into two or more simpler substances. In the equation, 2H2O (water) decomposes into 2H2 (hydrogen gas) and O2 (oxygen gas).

A single-displacement reaction occurs when one element replaces another element in a compound. In the given answer, "element + compound = element + compound," an element is reacting with a compound and replacing one of the elements in the compound. Therefore, this equation represents a single-displacement reaction.

The given balanced chemical equation shows the reaction between AgNO3 (silver nitrate) and NaCl (sodium chloride), resulting in the formation of AgCl (silver chloride) and NaNO3 (sodium nitrate). The equation is balanced because the number of atoms of each element is the same on both sides of the equation.

An activity series is useful for predicting whether a metal will replace another metal in a compound. This is because an activity series ranks metals based on their reactivity, with the most reactive metals at the top and the least reactive metals at the bottom. By comparing the position of two metals in the activity series, it can be determined whether a metal will replace another metal in a compound based on their relative reactivity.

Coefficients are the numbers that precede symbols and formulas in a chemical equation. They represent the relative number of molecules or atoms involved in the reaction. By adjusting the coefficients, we can balance the equation and ensure that the number of atoms of each element is equal on both sides of the equation. Subscripts, on the other hand, are used to indicate the number of atoms of an element within a molecule, while superscripts are used for indicating charges or indicating the number of atoms in a polyatomic ion. Fractions are not typically used as coefficients in chemical equations.