1.
In chemistry, a mole is:
Correct Answer
B. A quantity, not unlike a dozen
Explanation
The correct answer is "a quantity, not unlike a dozen." In chemistry, a mole is a unit used to represent a specific amount of a substance, just like a dozen represents a specific number of items. It is a way to count the quantity of particles, such as atoms or molecules, in a sample. The other options mentioned, such as the number of particles in an atom, the units used when counting mass, or the mass of a carbon-12 atom, are not accurate definitions of a mole.
2.
The concept of the mole allows chemists to:
Correct Answer
C. Go between number of particles and mass
Explanation
The concept of the mole allows chemists to go between the number of particles and mass. The mole is a unit that represents a specific number of particles, similar to how a dozen represents 12 items. By using the mole, chemists can convert between the number of particles (atoms, molecules, ions) and the mass of a substance. This is essential in various calculations and experiments in chemistry, such as determining the amount of reactants needed in a chemical reaction or finding the mass of a sample based on its chemical formula.
3.
What is the difference between molar mass and atomic mass?
Correct Answer
E. A and D
Explanation
Molar mass is the mass of a mole of a substance - measured in g/mol. Atomic mass is the mass of one atom of a substance - measured in atomic mass units.
4.
In quantitative chemistry, the symbol M stands for:
Correct Answer
B. Molar mass
Explanation
The symbol M in quantitative chemistry stands for molar mass. Molar mass is the mass of one mole of a substance and is expressed in grams per mole. It is calculated by summing up the atomic masses of all the atoms in a molecule. Molar mass is an important concept in stoichiometry and is used to convert between mass and moles in chemical calculations.
5.
In quantitative chemistry, the symbol m stands for:
Correct Answer
A. Mass
Explanation
The symbol "m" in quantitative chemistry stands for mass. This refers to the amount of matter present in a substance, typically measured in grams. Mass is an important concept in chemistry as it is used to calculate various quantities such as molar mass, amount in moles, and number of entities. By knowing the mass of a substance, one can determine its chemical properties and make calculations related to stoichiometry and reactions.
6.
In quantitative chemistry, the symbol n stands for:
Correct Answer
D. Amount in moles
Explanation
The symbol "n" in quantitative chemistry represents the amount in moles. Moles are a unit used to measure the quantity of a substance, similar to how we use "dozen" to represent 12 items. The amount in moles allows us to easily compare and calculate chemical reactions and quantities of substances. It is a fundamental concept in chemistry that helps in understanding and predicting the behavior of substances in various reactions and calculations.
7.
Which has more particles, a mole of sodium chloride, or a mole of water?
Correct Answer
C. Both have same amount
Explanation
A mole is defined as the amount of substance that contains the same number of particles as there are atoms in exactly 12 grams of carbon-12. Since both sodium chloride (NaCl) and water (H2O) have the same number of particles in a mole, which is 6.022 x 10^23 particles, the correct answer is that both have the same amount of particles.
8.
Calculate the molar mass of calcium hydroxide to three significant figures.
Correct Answer
74.1, 74.1 g, 74.1 grams
9.
If the molar mass of a substance is 67.2 g/mol, what is the mass of8.0 mol of the substance (in grams, to the appropriate number of sigfigs)?
Correct Answer
540g
540
540 g
Explanation
8.0 mol only has 2 significant figures
10.
Convert a mass of 2.5 g of table salt (sodium chloride) to an amountin moles.
Correct Answer
0.043
0.043 mol
0.043mol
Explanation
The given question asks to convert a mass of 2.5 g of table salt (sodium chloride) to an amount in moles. The correct answer is 0.043 mol. To convert grams to moles, we need to divide the mass of the substance by its molar mass. The molar mass of sodium chloride is approximately 58.44 g/mol. Dividing 2.5 g by 58.44 g/mol gives us the answer of 0.043 mol.