1.
What is a reaction in which one element replaces another in a compound, or in which two elements in a different compounds trade places?
Correct Answer
D. Replacement reaction
Explanation
A replacement reaction is a type of chemical reaction where one element replaces another in a compound, or where two elements in different compounds trade places. In this reaction, the elements essentially swap positions within the compounds involved. This type of reaction is also known as a displacement reaction, as one element displaces another from its original position in a compound.
2.
What is a solid that forms from a solution during a chemical reaction?
Correct Answer
C. Precipitate
Explanation
A solid that forms from a solution during a chemical reaction is called a precipitate. When certain chemicals are mixed together in a solution, a chemical reaction may occur, resulting in the formation of a solid substance that is insoluble in the solution. This solid substance is known as a precipitate. It is formed when the reaction causes the ions in the solution to combine and form a solid compound. Precipitates can be observed as a cloudy or solid material that settles at the bottom of the solution.
3.
What is a chemcal reaction that breaks down a compound into simpler products? 2 H2O2 yields 2 H2O + O2 (could not use yields symbol, the arrow)
Correct Answer
A. Decomposition
Explanation
A chemical reaction that breaks down a compound into simpler products is called decomposition. In this reaction, 2 H2O2 decomposes to form 2 H2O and O2. Decomposition reactions involve the breaking of chemical bonds within a compound, resulting in the formation of simpler substances.
4.
What is a chemical reaction in which two or more simple substances combine to form a new, more complex substance?
Correct Answer
B. Synthesis
Explanation
Synthesis is the correct answer because it refers to a chemical reaction where two or more simple substances combine to form a new, more complex substance. This process involves the creation of chemical bonds and the formation of a product that is different from the reactants. In a synthesis reaction, the total mass of the reactants is conserved, which aligns with the principle of conservation of mass.
5.
What is a number placed in front of a chemical formula in an equation that indicates how many atoms or molecules of each reactant and product are involved in a reaction? What is the 2 in the formual? 2 CuO + C
Correct Answer
D. Coefficient
Explanation
The number placed in front of a chemical formula in an equation is called a coefficient. In this equation, the coefficient "2" indicates that there are two molecules of CuO and one molecule of C involved in the reaction.
6.
What is the principle stating that matter is not created or desrtroyed during a chemical reaction?
Correct Answer
D. Conservation of mass
Explanation
The principle stating that matter is not created or destroyed during a chemical reaction is known as the conservation of mass. This principle states that the total mass of the reactants in a chemical reaction is equal to the total mass of the products. In other words, the mass of the substances involved in a chemical reaction remains constant before and after the reaction takes place. This principle is a fundamental concept in chemistry and is often used to balance chemical equations.
7.
What is a biological catalyst that lowers the activation energy of reactions in cells?
Correct Answer
A. Enzyme
Explanation
Enzymes are biological catalysts that lower the activation energy of reactions in cells. They speed up chemical reactions by providing an alternative pathway with a lower activation energy, allowing reactions to occur more easily and quickly. Enzymes are highly specific and can catalyze a wide range of reactions in cells, playing a crucial role in various metabolic processes. Unlike other catalysts, enzymes are not consumed during the reaction and can be used repeatedly.
8.
What is a material that increases the rate of a reaction by lowering the activation energy?
Correct Answer
B. Catalyst
Explanation
A catalyst is a material that increases the rate of a reaction by lowering the activation energy. It does this by providing an alternative reaction pathway with a lower energy barrier. This allows the reactants to more easily overcome the energy barrier and proceed to form the products. Catalysts are not consumed in the reaction and can be used repeatedly, making them highly efficient in increasing reaction rates.
9.
What is a material that decreases the rate of a reaction?
Correct Answer
A. Inhibitor
Explanation
An inhibitor is a substance that decreases the rate of a reaction. It works by interfering with the reaction mechanism, either by binding to the reactants or by blocking the active sites of enzymes. This prevents the reaction from proceeding at its normal rate. Inhibitors are often used in industrial processes to control the rate of reactions and prevent unwanted side reactions.
10.
What is the amount of energy dissolved in a given amount of another material?
Correct Answer
A. Concentration
Explanation
Concentration refers to the amount of a substance dissolved in a given amount of another material. It measures the quantity of solute (the substance being dissolved) per unit volume or mass of the solvent (the material in which the solute is dissolved). Therefore, concentration is the appropriate term to describe the amount of energy dissolved in a given amount of another material.
11.
What is a rapid reaction between oxygen and fuel that produces thermal energy?
Correct Answer
B. Combustion
Explanation
Combustion is the correct answer because it refers to the rapid reaction between oxygen and fuel that produces thermal energy. During combustion, the fuel combines with oxygen in the presence of heat or ignition source, resulting in the release of heat, light, and various combustion products. This process is commonly observed in everyday activities such as burning wood, gasoline, or natural gas, where the fuel reacts with oxygen to produce energy in the form of heat and light.
12.
What is the material that releases energy when it burns?
Correct Answer
C. Fuel
Explanation
Fuel is the correct answer because it is a material that releases energy when it burns. When fuel undergoes combustion, it reacts with oxygen in the air, producing heat and light energy. This process is known as an exothermic reaction, as it releases energy into the surroundings. Fuel can come in various forms, such as gasoline, wood, coal, or natural gas, and is commonly used to power vehicles, generate electricity, or provide heat for cooking and heating purposes.
13.
What is the minimum amount of energy needed to start a chemical reaction?
Correct Answer
C. Activation energy
Explanation
Activation energy is the minimum amount of energy required to start a chemical reaction. It is the energy needed to break the bonds in the reactant molecules and initiate the formation of new bonds in the product molecules. Without sufficient activation energy, the reaction cannot proceed. Activation energy acts as a barrier that needs to be overcome for a reaction to occur. Once the reaction has started and the bonds are broken, the reaction can continue on its own, releasing energy in the process.
14.
What is a reaction that absorbs energy in the form of heat?
Correct Answer
D. Endothermic reaction
Explanation
An endothermic reaction is a type of reaction that absorbs energy in the form of heat. In this reaction, the products have more energy than the reactants, resulting in a decrease in temperature of the surroundings. This is because the reaction requires an input of energy to break bonds and form new ones. As a result, the reaction feels cold to the touch and is often used in cold packs or instant ice packs.
15.
What is the reaction that releases energy in the form of heat?
Correct Answer
A. Exothermic reaction
Explanation
An exothermic reaction is a type of chemical reaction that releases energy in the form of heat. This means that during the reaction, the system loses energy to the surroundings, resulting in an increase in temperature. This release of energy is often accompanied by the production of heat, light, or sound. Examples of exothermic reactions include combustion, where a fuel reacts with oxygen to produce heat and light, and the reaction between an acid and a base, which also generates heat. In contrast, an endothermic reaction absorbs energy from the surroundings, causing a decrease in temperature.
16.
What is the minimum amount of energy needed to start a chemical reaction?
Correct Answer
A. Activation energy
Explanation
Activation energy is the minimum amount of energy required to initiate a chemical reaction. It is the energy barrier that must be overcome for the reactant molecules to transform into products. Without sufficient activation energy, the reaction will not occur. Catalysts can lower the activation energy by providing an alternative reaction pathway, while inhibitors can increase the activation energy, hindering the reaction. Fuel, on the other hand, is a substance that undergoes combustion reactions to release energy, but it is not directly related to the minimum energy required to start a chemical reaction.
17.
What is a short, easy way to show a chemical reaction, using symbols instead of words?
Correct Answer
B. Chemical equation
Explanation
A chemical equation is a short and easy way to show a chemical reaction using symbols instead of words. It represents the reactants and products involved in the reaction using chemical formulas and symbols. This allows for a concise representation of the reaction and helps to convey important information such as the stoichiometry and the balance of atoms. Therefore, a chemical equation is the correct answer to this question.
18.
What is a number in a chemical formula that tells the number of atoms in a molecule or the ratio of elements in a compound? What is the number 4? Example: Mg + CuSO4
Correct Answer
B. Subscript
Explanation
A subscript is a number in a chemical formula that tells the number of atoms in a molecule or the ratio of elements in a compound. In the given example, the number 4 is a subscript that indicates there are four oxygen atoms in the compound CuSO4.
19.
endothermic reaction picturesWhat is a subtance that enters into a chemical reaction?
Correct Answer
D. Reactant
Explanation
A substance that enters into a chemical reaction is called a reactant. In a chemical reaction, reactants are the starting materials that undergo a transformation to form new products. Reactants are typically written on the left side of a chemical equation, while the products are written on the right side. Reactants are necessary for a chemical reaction to occur and they are consumed during the reaction. In order to determine the amount of product formed, the stoichiometry of the reaction and the molar ratios between reactants and products must be considered.