🔥 Knowt Flashcard Set: Moles, Molar Mass, and Mass Conversions (30 Qs)

Q1: What is the molar mass of an element?

A1: The mass of one mole of an element in grams per mole (g/mol), numerically equal to its atomic mass.

Q2: What is a mole in chemistry?

A2: A unit representing

6.022

×

10

23

6.022×10

23

particles (atoms, molecules, ions, etc.).

Q3: What is Avogadro's number?

A3:

6.022

×

10

23

6.022×10

23

, the number of particles in one mole.

Q4: What is the formula to calculate moles from mass?

A4: Moles = mass (g) ÷ molar mass (g/mol)

Q5: What is the formula to calculate mass from moles?

A5: Mass = moles × molar mass

Q6: What is the formula to calculate molar mass from mass and moles?

A6: Molar mass = mass ÷ moles

Q7: How many moles are in 36 g of water (H₂O)?

A7: 2.00 moles (Molar mass = 18 g/mol, 36 ÷ 18 = 2)

Q8: How many grams are in 3 moles of carbon dioxide (CO₂)?

A8: 132.0 g (Molar mass = 44 g/mol, 3 × 44)

Q9: How many moles are in 100 g of sodium chloride (NaCl)?

A9: 1.71 mol (Molar mass = 58.44 g/mol, 100 ÷ 58.44)

Q10: How many atoms are in 2.00 mol of helium?

A10:

1.204

×

10

24

1.204×10

24

atoms (2 × Avogadro’s number)

🟩 FORMULA UNITS & MOLECULES

Q11: What is a formula unit?

A11: The simplest ratio of ions in an ionic compound.

Q12: How do you convert moles to formula units?

A12: Multiply moles by Avogadro’s number.

Q13: How do you find the number of formula units in 0.75 mol of NaCl?

A13:

4.52

×

10

23

4.52×10

23

formula units (0.75 × Avogadro’s number)

Q14: How many molecules are in 1.20 mol of H₂O?

A14:

7.23

×

10

23

7.23×10

23

molecules

Q15: How many moles are in

3.01

×

10

23

3.01×10

23

formula units of KBr?

A15: 0.500 mol

🟦 STEP-BY-STEP PRACTICE

Q16: What is the molar mass of Al₂S₃?

A16: 150.14 g/mol

Q17: How many moles are in 62.2 g of Al₂S₃?

A17: 0.4144 mol

Q18: How many formula units are in 62.2 g of Al₂S₃?

A18:

2.49

×

10