Understanding Chemical Reactions

What is a chemical reaction?

• A chemical reaction is a method of measuring temperature changes in substances.

• A chemical reaction is a process that only involves physical changes.

• A chemical reaction is a process where substances (reactants) are transformed into different substances (products) through the rearrangement of atoms.

• A chemical reaction is when substances are mixed without any change.

What are the signs of a chemical reaction?

• No change in color or temperature

• Color change, temperature change, formation of a precipitate, gas production, and change in properties.

• Absence of gas production

• Formation of a solid without a reaction

What is the difference between a reactant and a product?

• Reactants are the starting materials; products are the substances formed.

• Reactants are formed during a reaction; products are consumed.

• Reactants are the final outcome; products are the initial materials.

• Reactants are always gases; products are always solids.

What is the law of conservation of mass?

• Mass is only conserved in physical reactions.

• Mass can be created in chemical reactions.

• Mass is conserved in chemical reactions.

• Mass is lost during physical changes.

What are exothermic and endothermic reactions?

• Exothermic reactions release energy; endothermic reactions absorb energy.

• Exothermic reactions do not involve energy changes; endothermic reactions are spontaneous.

• Exothermic reactions are always faster than endothermic reactions.

• Exothermic reactions absorb energy; endothermic reactions release energy.

What role do catalysts play in chemical reactions?

• Catalysts speed up chemical reactions by lowering activation energy.

• Catalysts change the products of the reaction to create new substances.

• Catalysts are consumed in the reaction and do not affect the outcome.

• Catalysts slow down chemical reactions by increasing activation energy.

What is an acid-base reaction?

• A process where two acids combine to form a stronger acid.

• An acid-base reaction is a chemical process where an acid reacts with a base to produce water and a salt.

• A reaction between two bases that results in a gas.

• A reaction that only produces carbon dioxide and oxygen.

How do you balance a chemical equation?

• Count only the total number of molecules on each side.

• Change the chemical formulas to match the number of atoms.

• Balance the number of atoms of each element on both sides of the equation.

• Ignore the coefficients and focus on the subscripts.

What is the pH scale used for?

• To determine the color of a solution.

• To measure the temperature of a solution.

• The pH scale is used to measure the acidity or alkalinity of a solution.

• To assess the viscosity of a solution.

Can you name a common chemical reaction that occurs in everyday life?

• Precipitation

• Sublimation

• Fermentation

• Combustion