Amount Of Substance The Mole

Question 1

What is the quantity used to measure the amount of a substance?

Answer 1

The mole

A mole is a standard unit in chemistry used to express amounts of a chemical substance.

Question 2

How is the amount of substance calculated?

Answer 2

Using the equation: amount (mol) = mass (g) / molar mass (g/mol)

This equation can be rearranged to find mass or molar mass as needed.

Question 3

What is the molar mass of calcium?

Answer 3

40 g/mol

Molar mass is the mass of one mole of a substance, expressed in grams per mole.

Question 4

How many moles are in 10g of calcium?

Answer 4

0.25 mol

This is calculated using the formula: amount = mass / molar mass.

Question 5

What is the molar mass of oxygen gas (O2)?

Answer 5

32 g/mol

Oxygen gas consists of two oxygen atoms, hence the molar mass is double that of a single oxygen atom.

Question 6

How do you calculate the number of moles in 15.0 g of CaCO3?

Answer 6

1. Calculate molar mass (100.1 g/mol). 2. Use equation: amount = mass / molar mass = 15.0 / 100.1 = 0.150 mol

The molar mass is calculated by summing the atomic masses of all atoms in the compound.

Question 7

What is the mass of 1.40 mol of NaOH?

Answer 7

56.0 g

This is calculated using the formula: mass = amount x molar mass.

Question 8

If you have the mass and number of moles of a substance, how can you find its molar mass?

Answer 8

Use the formula: molar mass = mass / amount

This is useful for identifying unknown substances.

Question 9

What is the molar mass of a substance if 0.114 g corresponds to 0.00200 mol?

Answer 9

57.0 g/mol

This is calculated using the formula: molar mass = mass / amount.

Question 10

Fill in the blank: The mass of 1 mole of any substance is called its _______.

Answer 10

molar mass

Molar mass has units of g/mol.

Question 11

True or False: One mole of any substance contains the same number of particles as there are atoms in 12.00 g of carbon-12.

Answer 11

True

This is a fundamental concept in chemistry related to Avogadro’s number.

Question 12

What is the first step to calculate the molar mass of a compound like CaCO3?

Answer 12

Sum the atomic masses of the constituent elements

For CaCO3: 40.1 (Ca) + 12.0 (C) + (3 × 16.0 (O)) = 100.1 g/mol.

Question 13

What is the general formula to calculate amount in moles?

Answer 13

amount (mol) = mass (g) / molar mass (g/mol)

This formula can be rearranged to solve for mass or molar mass as needed.