a) A small animal that burrows underground.
b) A unit of measurement used to express the amount of a chemical substance.
c) A type of chemical reaction.
d) A unit of measurement used to express temperature.
Correct answer: b) A unit of measurement used to express the amount of a chemical substance.
Step 1: A mole is defined in chemistry as the amount of a chemical substance containing the same number of entities (atoms, molecules, ions) as there are in 12 grams of carbon-12.
Step 2: Explanation: A mole is used to compare similar amounts of various substances. It aids in standardizing the comparison of different substances’ amounts based on the number of entities. As a result, a mole is used to compare the amounts of substances directly.
Step 3: Thus, the best description of a mole is that it is utilized for directly comparing the amounts of substances.
Explanation: In chemistry, a mole is a unit of measurement used to express the amount of a chemical substance. It represents a specific number of particles, atoms, or molecules in a sample of a substance. One mole of a substance contains Avogadro’s number of particles, which is approximately 6.02 x 10^23. Therefore, option b is the correct answer. Options a, c, and d are incorrect.
Q: What is the formula to calculate the number of moles in a given mass of a substance?
A: The formula to calculate the number of moles in a given mass of a substance is:
moles = mass of substance (in grams) / molar mass of substance
Q: What is molar mass?
A: Molar mass is the mass of one mole of a substance, expressed in grams per mole. It is calculated by adding the atomic masses of all the atoms in a molecule.
Q: What is the relationship between moles and volume of a gas?
A: The relationship between moles and volume of a gas is given by Avogadro’s Law, which states that at constant temperature and pressure, the volume of a gas is directly proportional to the number of moles of gas present.
Q: What is the difference between molecular mass and molar mass?
A: Molecular mass is the mass of one molecule of a substance, while molar mass is the mass of one mole of a substance. Molecular mass is expressed in atomic mass units (amu), while molar mass is expressed in grams per mole.
Q: How is the concept of a mole used in stoichiometry?
A: The concept of a mole is used in stoichiometry to determine the amount of reactants and products in a chemical reaction. By using the stoichiometric coefficients in a balanced chemical equation, the number of moles of each substance involved in the reaction can be determined, which in turn can be used to calculate the mass or volume of each substance involved.
A: The formula to calculate the number of moles in a given mass of a substance is:
moles = mass of substance (in grams) / molar mass of substance
