Exploring Chemistry Concepts

What is the law of conservation of mass in chemical reactions?

• The total mass increases during a reaction.

• Mass is only conserved in physical changes.

• The total mass remains constant in chemical reactions.

• Mass can be created in chemical reactions.

Define a chemical reaction and provide an example.

• A chemical reaction is a physical change that does not involve any new substances, e.g., melting ice.

• A chemical reaction is the mixing of two substances without any change, e.g., stirring sugar in water.

• A chemical reaction is a process where reactants are converted into products, e.g., CH4 + 2 O2 → CO2 + 2 H2O.

• A chemical reaction is a process that occurs only in living organisms, e.g., photosynthesis.

What are the signs that a chemical reaction has occurred?

• Signs of a chemical reaction include gas formation, color change, temperature change, precipitate formation, and odor change.

• Change in the shape of a container

• Formation of a solid without a liquid

• Increase in the volume of a gas without a reaction

Explain the difference between an acid and a base.

• Acids have a pH above 7; bases have a pH below 7.

• Acids are always liquid; bases are always solid.

• Acids accept protons; bases donate protons.

• Acids donate protons; bases accept protons.

What is the pH scale and what does it measure?

• The pH scale measures the temperature of a solution.

• The pH scale measures the density of a solution.

• The pH scale indicates the color of a solution.

• The pH scale measures the concentration of hydrogen ions in a solution.

Describe the process of neutralization between an acid and a base.

• The process of neutralization between an acid and a base results in the formation of water and a salt.

• Neutralization results in the formation of hydrogen gas and a base.

• The reaction between an acid and a base creates a strong acid.

• The process of neutralization produces only carbon dioxide.

What are the common properties of acids?

• Common properties of acids include sour taste, ability to conduct electricity, proton donation, reaction with bases, and turning blue litmus paper red.

• Turning red litmus paper blue

• Ability to absorb heat

• Bitter taste

What are the common properties of bases?

• Feels rough and gritty

• Tastes sweet and sour

• Does not change the color of indicators

• Common properties of bases include being slippery, having a bitter taste, changing the color of indicators, and reacting with acids.

How do you balance a chemical equation?

• Add more atoms to one side without adjusting the other.

• Change the chemical formula to match one side.

• To balance a chemical equation, adjust the coefficients of the reactants and products to ensure the same number of each type of atom on both sides.

• Ignore the number of atoms and focus on the charge.

What is the role of catalysts in chemical reactions?

• Catalysts speed up chemical reactions by lowering activation energy.

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

• Catalysts slow down chemical reactions by increasing activation energy.

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