CH 3 PART 1 Flashcards
COVER EVERYTHING (21 cards)
What is atomic mass?
The weighted average mass of an atom of an element based on the relative abundance of its isotopes.
What is Avogadro’s number?
6.022 x 10^23, which represents the number of particles in one mole of a substance.
True or False: Molar mass is the mass of one mole of a substance expressed in grams.
True
Fill in the blank: The molar mass of an element in grams per mole is numerically equal to its ______.
atomic mass
What unit is used to express molecular mass?
Unified atomic mass units (u) or daltons (Da).
How do you calculate the number of moles from mass?
Number of moles = mass (g) / molar mass (g/mol).
Which element has an atomic mass approximately equal to 12 u?
Carbon (C).
What is the relationship between moles and molecules?
One mole of any substance contains Avogadro’s number of molecules.
True or False: The molecular mass of water (H2O) is 18 u.
True
What is the molar mass of sodium chloride (NaCl)?
Approximately 58.44 g/mol.
Fill in the blank: The number of atoms in 1 mole of an element is known as ______.
Avogadro’s number
What is the molecular mass of glucose (C6H12O6)?
Approximately 180.18 u.
How many grams are in 2 moles of water?
36 grams.
What is the formula to find molar mass?
Molar mass = mass of the substance / amount of substance in moles.
True or False: Molar mass can vary depending on the isotopic composition of an element.
True
What does the term ‘mole’ represent in chemistry?
A quantity of substance that contains as many entities as there are atoms in 12 grams of carbon-12.
Calculate the number of moles in 50 grams of carbon (C) if its molar mass is 12 g/mol.
4.17 moles.
What is the molecular mass of nitrogen gas (N2)?
Approximately 28 u.
What is the significance of Avogadro’s number in chemistry?
It allows chemists to count particles by weighing them.
True or False: The atomic mass of an element is always a whole number.
False
